Merge branch 'master' into Extra-VAXen

Conflicts: makefile
2011-11-10 09:04:42 -08:00 · 2011-11-10 09:04:42 -08:00 · 3e10dfbd95
commit 3e10dfbd95
parent 0705a6b468 f9521eaf01
25 changed files with 2029 additions and 1269 deletions
--- a/0readmeAsynchIO.txt
+++ b/0readmeAsynchIO.txt
@ -5,6 +5,9 @@ Theory of operation.
 Features.
   - Optional Use.  Build with or without SIM_ASYNCH_IO defined and 
     simulators will still build and perform correctly when run.
     Additionmally, a simulator built with SIM_ASYNCH_IO defined can
     dynamically disable and reenable asynchronous operation with 
     the scp commands SET NOASYNCH and SET ASYNCH respectively.
   - Consistent Save/Restore state.  The state of a simulator saved 
     on a simulator with (or without) Asynch support can be restored
     on any simulator of the same version with or without Asynch 
--- a/0readme_ethernet.txt
+++ b/0readme_ethernet.txt
@ -43,9 +43,9 @@ bridge, or route TAP devices for you.
 Integrated Universal TUN/TAP support can be used for host<->simulator network
 traffic (on the platforms where it is available) by using the SIMH command:
 "attach xq tap:tapN" (i.e. attach xq tap:tap0).  Platforms that this has been
-tested on include: Linux, FreeBSD, OpenBSD, NetBSD.  Each of these platforms
+tested on include: Linux, FreeBSD, OpenBSD, NetBSD and OSX.  Each of these 
-has some way to create a tap pseudo device and then bridge it with a physical
+platforms has some way to create a tap pseudo device (and possibly then to 
-network interface.
+bridge it with a physical network interface).
 The following steps were performed to get a working SIMH vax simulator 
 sharing a physical NIC and allowing Host<->SIMH vax communications:
@ -117,6 +117,53 @@ NetBSD (NetBSD 5.0.2)
    # Run simulator and "attach xq tap:tap0"
 OSX (Snow Leopard)
    OSX Does NOT have native support for tun/tap interfaces.  It also does not have native
    support for bridging.
    Mattias Nissler has created tun/tap functionality available at http://tuntaposx,sourceforge.net/
    We'll punt on bridging for the sake of this example and move on to use a basic tap
    based internal network so a host and guest can communicate directly.
    Download the install package from: 
    http://sourceforge.net/projects/tuntaposx/files/tuntap/20090913/tuntap_20090913.tar.gz
    Expand the tarball to a directory.
    Invoke the package installer tuntap_20090913.pkg
    Click through the various prompts accepting things and eventually installing the package.
    # Build and Run simulator and:
       sim> attach xq tap:tap0
       sim> ! ifconfig tap0 192.168.6.1 netmask 255.255.255.0
    Simulated system uses IP address 192.168.6.2 and host uses 192.167.6.1 
    and things work.
    You must run as root for this to work.
 -------------------------------------------------------------------------------
 An alternative to direct pcap and tun/tap networking on *nix environments is 
 VDE (Virtual Distributed Ethernet).
 Note 1: Using vde based networking is likely more flexible, but it isn't 
        nearly as efficient.  Host OS overhead will always be higher when 
        vde networking is used as compared to native pcap and/or tun/tap 
        networking.
 Note 2: Root access will likely be needed to configure or start the vde 
        environment prior to starting a simulator which may use it.
 Note 3: Simulators running using VDE networking can run without root 
        privilege.
 Linux (Ubuntu 10.04):
    apt-get install libvdeplug-dev
    apt-get install vde2
    vde_switch -s /tmp/switch1 -tap tap0 -m 666
    ifconfig tap0 192.168.6.1 netmask 255.255.255.0 up
    # Build and Run simulator and:
       sim> attach xq vde:/tmp/switch1  #simulator uses IP address 192.168.6.2
 -------------------------------------------------------------------------------
 Windows notes:
@ -134,6 +181,11 @@ Windows notes:
 Building on Windows:
 Building with MinGW can use the provided makefile following the instructions 
 below.  Alternatively, you can use the free Visual C++ Express 2008 or 2010
 interactive development environments.  Read the file 
 ".\Visual Studio Projects\0ReadMe_Projects.txt" for details.
 1. Install WinPCAP 4.x runtime and the WinPCAP Developer's kit.
 2. Put the required .h files (bittypes,devioctl,ip6_misc,pcap,pcap-stdinc
@ -159,8 +211,11 @@ Linux, {Free|Net|Open}BSD, OS/X, and Un*x notes:
 ----- WARNING ----- WARNING ----- WARNING ----- WARNING ----- WARNING -----
 Sim_Ether has been reworked to be more universal; because of this, you will
-need to get a version of libpcap that is 0.9 or greater. This can be
+need to get a version of libpcap that is 0.9 or greater. All current Linux
-downloaded from www.tcpdump.org - see the comments at the top of Sim_ether.c
+distributions provide a libpcap-dev package which has the needed version
 of libpcap and the required components to build applications using it.  
 If you are running an older Linux OS, you can download and build the required 
 library from www.tcpdump.org - see the comments at the top of Sim_ether.c 
 for details.  
 ----- WARNING ----- WARNING ----- WARNING ----- WARNING ----- WARNING -----
@ -187,11 +242,13 @@ for details.
    will be welcomed.
 2. If you want to use TAP devices, and any surrounding system network/bridge
-    setup must be done before running SIMH.
+    setup must be done before running SIMH.  However, once that is done 
    (possibly at system boot time), using the TAP devices can be done without
    root privileges.
 Building on Linux, {Free|Net|Open}BSD, OS/X, Un*x:
- 1. Get/make/install the libpcap package for your operating system. Sources:
+ 1. Get/make/install the libpcap-dev package for your operating system. Sources:
      All    : http://www.tcpdump.org/
      Older versions of libpcap can be found, for various systems, at:
      Linux  : search for your variant on http://rpmfind.net
@ -214,7 +271,7 @@ Building on Linux, {Free|Net|Open}BSD, OS/X, Un*x:
 -------------------------------------------------------------------------------
-OpenVMS Alpha notes:
+OpenVMS Alpha and OpenVMS Integrety (IA64) notes:
  1. Ethernet support will only work on Alpha VMS 7.3-1 or later, which is
     when required VCI promiscuous mode support was added. Hobbyists can
     get the required version of VMS from the OpenVMS Alpha Hobbyist Kit 3.0.
@ -247,10 +304,10 @@ OpenVMS Alpha notes:
     adapter prior trying to connect with SIMH, or the host may crash.
     The execlet is not written to create an I/O structure for the device.
-Building on OpenVMS Alpha:
+Building on OpenVMS Alpha and OpenVMS Integrety (IA64):
  The current descrip.mms file will build simulators capable of using
  Ethernet support with them automatically.  These currently are: VAX, 
-  PDP11, and PDP10.  The descrip.mms driven builds will also build the
+  VAX780, and PDP11.  The descrip.mms driven builds will also build the
  pcap library and build and install the VCI execlet.
  1. Fetch the VMS-PCAP zip file from:  
@ -321,6 +378,17 @@ Dave
                               Change Log
 ===============================================================================
  30-Oct-11  MP   Added support for vde (Virtual Distributed Ethernet) networking
  29-Oct-11  MP   Added support for integrated Tap networking interfaces on OSX
  17-Aug-11  RMS  Fix from Sergey Oboguev relating to XU and XQ Auto Config and 
                  vector assignments
  12-Aug-11  MP   Cleaned up payload length determination
                  Fixed race condition detecting reflections when threaded 
                  reading and writing is enabled
  07-Jul-11  MB   VMS Pcap (from Mike Burke)
                     - Fixed Alpha issues
                     - Added OpenVMS Integrety support
  20-Apr-11  MP   Fixed save/restore behavior
  12-Jan-11  DTH  Added SHOW XU FILTERS modifier
  11-Jan-11  DTH  Corrected DEUNA/DELUA SELFTEST command, enabling use by
                  VMS 3.7, VMS 4.7, and Ultrix 1.1
--- a/PDP11/pdp11_tu.c
+++ b/PDP11/pdp11_tu.c
@ -469,7 +469,7 @@ den = GET_DEN (tutc);                                   /* get density */
 uptr = tu_dev.units + drv;                              /* get unit */
 if (DEBUG_PRS (tu_dev)) {
    fprintf (sim_deb, ">>TU%d STRT: fnc=%s, fc=%06o, fs=%06o, er=%06o, pos=",
-             drv, tu_fname[fnc], tufc, tufs, tuer, uptr->pos);
+             drv, tu_fname[fnc], tufc, tufs, tuer);
    fprint_val (sim_deb, uptr->pos, 10, T_ADDR_W, PV_LEFT);
    fprintf (sim_deb, "\n");
    }
--- a/PDP11/pdp11_xq.c
+++ b/PDP11/pdp11_xq.c
@ -2584,6 +2584,7 @@ t_stat xq_attach(UNIT* uptr, char* cptr)
  if (xq->var->poll == 0) {
    status = eth_set_async(xq->var->etherface, xq->var->coalesce_latency_ticks);
    if (status != SCPE_OK) {
      eth_close(xq->var->etherface);
      free(tptr);
      free(xq->var->etherface);
      xq->var->etherface = NULL;
--- a/PDP11/pdp11_xq.h
+++ b/PDP11/pdp11_xq.h
@ -87,7 +87,7 @@ extern int32 int_req[IPL_HLVL];
 #define XQ_QUE_MAX           500                        /* read queue size in packets */
 #define XQ_FILTER_MAX         14                        /* number of filters allowed */
-#if defined SIM_ASYNCH_IO
+#if defined(SIM_ASYNCH_IO) && defined(USE_READER_THREAD)
 #define XQ_SERVICE_INTERVAL  0                          /* polling interval - No Polling with Asynch I/O */
 #else
 #define XQ_SERVICE_INTERVAL  100                        /* polling interval - X per second */
--- a/PDP8/pdp8_fpp.c
+++ b/PDP8/pdp8_fpp.c
@ -1,6 +1,6 @@
 /* pdp8_fpp.c: PDP-8 floating point processor (FPP8A)
-   Copyright (c) 2007-2011, Robert M Supnik
+   Copyright (c) 2007-2010, Robert M Supnik
   Permission is hereby granted, free of charge, to any person obtaining a
   copy of this software and associated documentation files (the "Software"),
--- a/PDP8/pdp8_sys.c
+++ b/PDP8/pdp8_sys.c
@ -1,6 +1,6 @@
 /* pdp8_sys.c: PDP-8 simulator interface
-   Copyright (c) 1993-2011, Robert M Supnik
+   Copyright (c) 1993-2009, Robert M Supnik
   Permission is hereby granted, free of charge, to any person obtaining a
   copy of this software and associated documentation files (the "Software"),
@ -24,7 +24,7 @@
   in this Software without prior written authorization from Robert M Supnik.
   24-Mar-09    RMS     Added link to FPP
-   24-Jun-08    RMS     Fixed bug in new rim loader (Don North)
+   24-Jun-08    RMS     Fixed bug in new rim loader (found by Don North)
   24-May-08    RMS     Fixed signed/unsigned declaration inconsistency
   03-Sep-07    RMS     Added FPP8 support
                        Rewrote rim and binary loaders
--- a/PDP8/pdp8_td.c
+++ b/PDP8/pdp8_td.c
@ -28,6 +28,7 @@
   td           TD8E/TU56 DECtape
   23-Mar-11    RMS     Fixed SDLC to clear AC (from Dave Gesswein)
   23-Jun-06	RMS     Fixed switch conflict in ATTACH
   16-Aug-05    RMS     Fixed C++ declaration and cast problems
   09-Jan-04    RMS     Changed sim_fsize calling sequence, added STOP_OFFR
@ -302,6 +303,7 @@ switch (pulse) {
            if (td_newsa (td_cmd))                      /* new command */
                return AC | (IORETURN (td_stopoffr, STOP_DTOFF) << IOT_V_REASON);
            }
        AC = 0;
        break;
    case 05:                                            /* SDLD */
--- a/VAX/vax730_stddev.c
+++ b/VAX/vax730_stddev.c
@ -30,11 +30,34 @@
   todr         TODR clock
   tmr          interval timer
   28-Sep-11    MP      Generalized setting TODR for all OSes.  
                        Unbound the TODR value from the 100hz clock tick 
                        interrupt.  TODR now behaves like the original 
                        battery backed-up clock and runs with the wall 
                        clock, not the simulated instruction clock.  
                        Two operational modes are available:
                        - Default VMS mode, which is similar to the previous 
                          behavior in that without initializing the TODR it 
                          would default to the value VMS would set it to if
                          VMS knew the correct time.  This would be correct
                          almost all the time unless a VMS disk hadn't been
                          booted from for more than a year.  This mode 
                          produces strange time results for non VMS OSes on 
                          each system boot.
                        - OS Agnostic mode.  This mode behaves precisely like
                          the VAX780 TODR and works correctly for all OSes.  
                          This mode is enabled by attaching the TODR to a 
                          battery backup state file for the TOY clock 
                          (i.e. sim> attach TODR TOY_CLOCK).  When operating 
                          in OS Agnostic mode, the TODR will initially start
                          counting from 0 and be adjusted differently when an
                          OS specifically writes to the TODR.  VMS will prompt
                          to set the time on each boot unless the SYSGEN 
                          parameter TIMEPROMPTWAIT is set to 0.
   29-Mar-2011  MB      First Version
 */
 #include "vax_defs.h"
 #include <time.h>
 /* Terminal definitions */
@ -159,6 +182,11 @@ int32 clk_tps = 100;                                    /* ticks/second */
 int32 tmxr_poll = CLK_DELAY * TMXR_MULT;                /* term mux poll */
 int32 tmr_poll = CLK_DELAY;                             /* pgm timer poll */
 int32 todr_reg = 0;                                     /* TODR register */
 struct todr_battery_info {
    uint32 toy_gmtbase;                                 /* GMT base of set value */
    uint32 toy_gmtbasemsec;                             /* The milliseconds of the set value */
    };
 typedef struct todr_battery_info TOY;
 int32 td_swait = 100;                                   /* seek, per block */
 int32 td_cwait = 150;                                   /* command time */
@ -187,6 +215,8 @@ t_stat tmr_svc (UNIT *uptr);
 t_stat tti_reset (DEVICE *dptr);
 t_stat tto_reset (DEVICE *dptr);
 t_stat clk_reset (DEVICE *dptr);
 t_stat clk_attach (UNIT *uptr, char *cptr);
 t_stat clk_detach (UNIT *uptr);
 t_stat tmr_reset (DEVICE *dptr);
 t_stat td_svc (UNIT *uptr);
 t_stat td_reset (DEVICE *dptr);
@ -269,7 +299,7 @@ DEVICE tto_dev = {
 /* TODR and TMR data structures */
-UNIT clk_unit = { UDATA (&clk_svc, UNIT_IDLE, 0), CLK_DELAY };          /* 100Hz */
+UNIT clk_unit = { UDATA (&clk_svc, UNIT_IDLE+UNIT_FIX, sizeof(TOY)), CLK_DELAY };/* 100Hz */
 REG clk_reg[] = {
    { DRDATA (TODR, todr_reg, 32), PV_LEFT },
@ -280,9 +310,9 @@ REG clk_reg[] = {
 DEVICE clk_dev = {
    "TODR", &clk_unit, clk_reg, NULL,
-    1, 0, 0, 0, 0, 0,
+    1, 0, 8, 1, 0, 0,
    NULL, NULL, &clk_reset,
-    NULL, NULL, NULL,
+    NULL, &clk_attach, &clk_detach,
    NULL, 0
    };
@ -763,7 +793,6 @@ t_stat clk_svc (UNIT *uptr)
 tmr_poll = sim_rtcn_calb (clk_tps, TMR_CLK);            /* calibrate clock */
 sim_activate (&clk_unit, tmr_poll);                     /* reactivate unit */
 tmxr_poll = tmr_poll * TMXR_MULT;                       /* set mux poll */
 todr_reg = todr_reg + 1;                                /* incr TODR */
 if ((tmr_iccs & TMR_CSR_RUN) && tmr_use_100hz)          /* timer on, std intvl? */
    tmr_incr (TMR_INC);                                 /* do timer service */
 return SCPE_OK;
@ -836,9 +865,44 @@ t_stat clk_reset (DEVICE *dptr)
 tmr_poll = sim_rtcn_init (clk_unit.wait, TMR_CLK);      /* init 100Hz timer */
 sim_activate_abs (&clk_unit, tmr_poll);                 /* activate 100Hz unit */
 tmxr_poll = tmr_poll * TMXR_MULT;                       /* set mux poll */
 if (clk_unit.filebuf == NULL) {                         /* make sure the TODR is initialized */
    clk_unit.filebuf = calloc(sizeof(TOY), 1);
    if (clk_unit.filebuf == NULL)
        return SCPE_MEM;
    todr_resync ();
    }
 return SCPE_OK;
 }
 /* CLK attach */
 t_stat clk_attach (UNIT *uptr, char *cptr)
 {
 t_stat r;
 uptr->flags = uptr->flags | (UNIT_ATTABLE | UNIT_BUFABLE);
 memset (uptr->filebuf, 0, (size_t)uptr->capac);
 r = attach_unit (uptr, cptr);
 if (r != SCPE_OK)
    uptr->flags = uptr->flags & ~(UNIT_ATTABLE | UNIT_BUFABLE);
 else
    uptr->hwmark = (uint32) uptr->capac;
 return r;
 }
 /* CLK detach */
 t_stat clk_detach (UNIT *uptr)
 {
 t_stat r;
 r = detach_unit (uptr);
 if ((uptr->flags & UNIT_ATT) == 0)
    uptr->flags = uptr->flags & ~(UNIT_ATTABLE | UNIT_BUFABLE);
 return r;
 }
 /* Interval timer reset */
 t_stat tmr_reset (DEVICE *dptr)
@ -857,18 +921,43 @@ return SCPE_OK;
 int32 todr_rd (void)
 {
-return todr_reg;
+TOY *toy = (TOY *)clk_unit.filebuf;
 struct timespec base, now, val;
 clock_gettime(CLOCK_REALTIME, &now);                    /* get curr time */
 base.tv_sec = toy->toy_gmtbase;
 base.tv_nsec = toy->toy_gmtbasemsec * 1000000;
 sim_timespec_diff (&val, &now, &base);
 return (int32)(val.tv_sec*100 + val.tv_nsec/10000000);  /* 100hz Clock Ticks */
 }
 void todr_wr (int32 data)
 {
-todr_reg = data;
+TOY *toy = (TOY *)clk_unit.filebuf;
-return;
+struct timespec now, val, base;
 /* Save the GMT time when set value was 0 to record the base for future 
   read operations in "battery backed-up" state */
 if (-1 == clock_gettime(CLOCK_REALTIME, &now))          /* get curr time */
    return;                                             /* error? */
 val.tv_sec = ((uint32)data) / 100;
 val.tv_nsec = (((uint32)data) % 100) * 10000000;
 sim_timespec_diff (&base, &now, &val);                  /* base = now - data */
 toy->toy_gmtbase = base.tv_sec;
 toy->toy_gmtbasemsec = base.tv_nsec/1000000;
 }
 t_stat todr_resync (void)
 {
-uint32 base;
+TOY *toy = (TOY *)clk_unit.filebuf;
 if (clk_unit.flags & UNIT_ATT) {                        /* Attached means behave like real VAX780 */
    if (!toy->toy_gmtbase)                              /* Never set? */
        todr_wr (0);                                    /* Start ticking from 0 */
    }
 else {                                                  /* Not-Attached means */
    uint32 base;                                        /* behave like simh VMS default */
    time_t curr;
    struct tm *ctm;
@ -882,7 +971,8 @@ base = (((((ctm->tm_yday * 24) +                        /* sec since 1-Jan */
            ctm->tm_hour) * 60) +
            ctm->tm_min) * 60) +
            ctm->tm_sec;
-todr_reg = (base * 100) + 0x10000000;                   /* cvt to VAX form */
+    todr_wr ((base * 100) + 0x10000000);                /* use VMS form */
    }
 return SCPE_OK;
 }
--- a/VAX/vax780_stddev.c
+++ b/VAX/vax780_stddev.c
@ -29,6 +29,30 @@
   todr         TODR clock
   tmr          interval timer
   28-Sep-11    MP      Generalized setting TODR for all OSes.  
                        Unbound the TODR value from the 100hz clock tick 
                        interrupt.  TODR now behaves like the original 
                        battery backed-up clock and runs with the wall 
                        clock, not the simulated instruction clock.  
                        Two operational modes are available:
                        - Default VMS mode, which is similar to the previous 
                          behavior in that without initializing the TODR it 
                          would default to the value VMS would set it to if
                          VMS knew the correct time.  This would be correct
                          almost all the time unless a VMS disk hadn't been
                          booted from for more than a year.  This mode 
                          produces strange time results for non VMS OSes on 
                          each system boot.
                        - OS Agnostic mode.  This mode behaves precisely like
                          the VAX780 TODR and works correctly for all OSes.  
                          This mode is enabled by attaching the TODR to a 
                          battery backup state file for the TOY clock 
                          (i.e. sim> attach TODR TOY_CLOCK).  When operating 
                          in OS Agnostic mode, the TODR will initially start
                          counting from 0 and be adjusted differently when an
                          OS specifically writes to the TODR.  VMS will prompt
                          to set the time on each boot unless the SYSGEN 
                          parameter TIMEPROMPTWAIT is set to 0.
   21-Mar-11    RMS     Added reboot capability
   17-Aug-08    RMS     Resync TODR on any clock reset
   18-Jun-07    RMS     Added UNIT_IDLE flag to console input, clock
@ -56,7 +80,7 @@
 */
 #include "vax_defs.h"
-#include <time.h>
+
 /* Terminal definitions */
@ -171,6 +195,11 @@ int32 clk_tps = 100;                                    /* ticks/second */
 int32 tmxr_poll = CLK_DELAY * TMXR_MULT;                /* term mux poll */
 int32 tmr_poll = CLK_DELAY;                             /* pgm timer poll */
 int32 todr_reg = 0;                                     /* TODR register */
 struct todr_battery_info {
    uint32 toy_gmtbase;                                 /* GMT base of set value */
    uint32 toy_gmtbasemsec;                             /* The milliseconds of the set value */
    };
 typedef struct todr_battery_info TOY;
 int32 fl_fnc = 0;                                       /* function */
 int32 fl_esr = 0;                                       /* error status */
@ -197,6 +226,8 @@ t_stat tmr_svc (UNIT *uptr);
 t_stat tti_reset (DEVICE *dptr);
 t_stat tto_reset (DEVICE *dptr);
 t_stat clk_reset (DEVICE *dptr);
 t_stat clk_attach (UNIT *uptr, char *cptr);
 t_stat clk_detach (UNIT *uptr);
 t_stat tmr_reset (DEVICE *dptr);
 t_stat fl_svc (UNIT *uptr);
 t_stat fl_reset (DEVICE *dptr);
@ -281,7 +312,7 @@ DEVICE tto_dev = {
 /* TODR and TMR data structures */
-UNIT clk_unit = { UDATA (&clk_svc, UNIT_IDLE, 0), CLK_DELAY };          /* 100Hz */
+UNIT clk_unit = { UDATA (&clk_svc, UNIT_IDLE+UNIT_FIX, sizeof(TOY)), CLK_DELAY };/* 100Hz */
 REG clk_reg[] = {
    { DRDATA (TODR, todr_reg, 32), PV_LEFT },
@ -296,9 +327,9 @@ REG clk_reg[] = {
 DEVICE clk_dev = {
    "TODR", &clk_unit, clk_reg, NULL,
-    1, 0, 0, 0, 0, 0,
+    1, 0, 8, 1, 0, 0,
    NULL, NULL, &clk_reset,
-    NULL, NULL, NULL,
+    NULL, &clk_attach, &clk_detach,
    NULL, 0
    };
@ -578,7 +609,6 @@ tmr_poll = sim_rtcn_calb (clk_tps, TMR_CLK);            /* calibrate clock */
 sim_activate (&clk_unit, tmr_poll);                     /* reactivate unit */
 tmxr_poll = tmr_poll * TMXR_MULT;                       /* set mux poll */
 AIO_SET_INTERRUPT_LATENCY(tmr_poll*clk_tps);            /* set interrrupt latency */
 todr_reg = todr_reg + 1;                                /* incr TODR */
 if ((tmr_iccs & TMR_CSR_RUN) && tmr_use_100hz)          /* timer on, std intvl? */
    tmr_incr (TMR_INC);                                 /* do timer service */
 return SCPE_OK;
@ -651,9 +681,44 @@ t_stat clk_reset (DEVICE *dptr)
 tmr_poll = sim_rtcn_init (clk_unit.wait, TMR_CLK);      /* init 100Hz timer */
 sim_activate_abs (&clk_unit, tmr_poll);                 /* activate 100Hz unit */
 tmxr_poll = tmr_poll * TMXR_MULT;                       /* set mux poll */
 if (clk_unit.filebuf == NULL) {                         /* make sure the TODR is initialized */
    clk_unit.filebuf = calloc(sizeof(TOY), 1);
    if (clk_unit.filebuf == NULL)
        return SCPE_MEM;
    todr_resync ();
    }
 return SCPE_OK;
 }
 /* CLK attach */
 t_stat clk_attach (UNIT *uptr, char *cptr)
 {
 t_stat r;
 uptr->flags = uptr->flags | (UNIT_ATTABLE | UNIT_BUFABLE);
 memset (uptr->filebuf, 0, (size_t)uptr->capac);
 r = attach_unit (uptr, cptr);
 if (r != SCPE_OK)
    uptr->flags = uptr->flags & ~(UNIT_ATTABLE | UNIT_BUFABLE);
 else
    uptr->hwmark = (uint32) uptr->capac;
 return r;
 }
 /* CLK detach */
 t_stat clk_detach (UNIT *uptr)
 {
 t_stat r;
 r = detach_unit (uptr);
 if ((uptr->flags & UNIT_ATT) == 0)
    uptr->flags = uptr->flags & ~(UNIT_ATTABLE | UNIT_BUFABLE);
 return r;
 }
 /* Interval timer reset */
 t_stat tmr_reset (DEVICE *dptr)
@ -672,18 +737,44 @@ return SCPE_OK;
 int32 todr_rd (void)
 {
-return todr_reg;
+TOY *toy = (TOY *)clk_unit.filebuf;
 struct timespec base, now, val;
 clock_gettime(CLOCK_REALTIME, &now);                    /* get curr time */
 base.tv_sec = toy->toy_gmtbase;
 base.tv_nsec = toy->toy_gmtbasemsec * 1000000;
 sim_timespec_diff (&val, &now, &base);
 return (int32)(val.tv_sec*100 + val.tv_nsec/10000000);  /* 100hz Clock Ticks */
 }
 void todr_wr (int32 data)
 {
-todr_reg = data;
+TOY *toy = (TOY *)clk_unit.filebuf;
-return;
+struct timespec now, val, base;
 /* Save the GMT time when set value was 0 to record the base for future 
   read operations in "battery backed-up" state */
 if (-1 == clock_gettime(CLOCK_REALTIME, &now))          /* get curr time */
    return;                                             /* error? */
 val.tv_sec = ((uint32)data) / 100;
 val.tv_nsec = (((uint32)data) % 100) * 10000000;
 sim_timespec_diff (&base, &now, &val);                  /* base = now - data */
 toy->toy_gmtbase = base.tv_sec;
 toy->toy_gmtbasemsec = base.tv_nsec/1000000;
 }
 t_stat todr_resync (void)
 {
-uint32 base;
+TOY *toy = (TOY *)clk_unit.filebuf;
 if (clk_unit.flags & UNIT_ATT) {                        /* Attached means behave like real VAX780 */
    if (!toy->toy_gmtbase)                              /* Never set? */
        todr_wr (0);                                    /* Start ticking from 0 */
    }
 else {                                                  /* Not-Attached means */
    uint32 base;                                        /* behave like simh VMS default */
    time_t curr;
    struct tm *ctm;
@ -697,7 +788,8 @@ base = (((((ctm->tm_yday * 24) +                        /* sec since 1-Jan */
            ctm->tm_hour) * 60) +
            ctm->tm_min) * 60) +
            ctm->tm_sec;
-todr_reg = (base * 100) + 0x10000000;                   /* cvt to VAX form */
+    todr_wr ((base * 100) + 0x10000000);                /* use VMS form */
    }
 return SCPE_OK;
 }
--- a/VAX/vax_stddev.c
+++ b/VAX/vax_stddev.c
@ -27,6 +27,31 @@
   tto          terminal output
   clk          100Hz and TODR clock
   28-Sep-11    MP      Generalized setting TODR for all OSes.  
                        Unbound the TODR value from the 100hz clock tick 
                        interrupt.  TODR now behaves like the original 
                        battery backed-up clock and runs with the wall 
                        clock, not the simulated instruction clock
                        (except when running ROM diagnostics).
                        Two operational modes are available:
                        - Default VMS mode, which is similar to the previous 
                          behavior in that without initializing the TODR it 
                          would default to the value VMS would set it to if
                          VMS knew the correct time.  This would be correct
                          almost all the time unless a VMS disk hadn't been
                          booted from for more than a year.  This mode 
                          produces strange time results for non VMS OSes on 
                          each system boot.
                        - OS Agnostic mode.  This mode behaves precisely like
                          the VAX780 TODR and works correctly for all OSes.  
                          This mode is enabled by attaching the TODR to a 
                          battery backup state file for the TOY clock 
                          (i.e. sim> attach TODR TOY_CLOCK).  When operating 
                          in OS Agnostic mode, the TODR will initially start
                          counting from 0 and be adjusted differently when an
                          OS specifically writes to the TODR.  VMS will prompt
                          to set the time on each boot unless the SYSGEN 
                          parameter TIMEPROMPTWAIT is set to 0.
   05-Jan-11    MP      Added Asynch I/O support
   17-Aug-08    RMS     Resync TODR on any clock reset
   18-Jun-07    RMS     Added UNIT_IDLE flag to console input, clock
@ -70,6 +95,11 @@ int32 clk_csr = 0;                                      /* control/status */
 int32 clk_tps = 100;                                    /* ticks/second */
 int32 todr_reg = 0;                                     /* TODR register */
 int32 todr_blow = 1;                                    /* TODR battery low */
 struct todr_battery_info {
    uint32 toy_gmtbase;                                 /* GMT base of set value */
    uint32 toy_gmtbasemsec;                             /* The milliseconds of the set value */
    };
 typedef struct todr_battery_info TOY;
 int32 tmxr_poll = CLK_DELAY * TMXR_MULT;                /* term mux poll */
 int32 tmr_poll = CLK_DELAY;                             /* pgm timer poll */
@ -79,9 +109,12 @@ t_stat clk_svc (UNIT *uptr);
 t_stat tti_reset (DEVICE *dptr);
 t_stat tto_reset (DEVICE *dptr);
 t_stat clk_reset (DEVICE *dptr);
 t_stat clk_attach (UNIT *uptr, char *cptr);
 t_stat clk_detach (UNIT *uptr);
 t_stat todr_resync (void);
 extern int32 sysd_hlt_enb (void);
 extern int32 fault_PC;
 /* TTI data structures
@ -168,7 +201,7 @@ DEVICE tto_dev = {
 DIB clk_dib = { 0, 0, NULL, NULL, 1, IVCL (CLK), SCB_INTTIM, { NULL } };
-UNIT clk_unit = { UDATA (&clk_svc, UNIT_IDLE, 0), CLK_DELAY };
+UNIT clk_unit = { UDATA (&clk_svc, UNIT_IDLE+UNIT_FIX, sizeof(TOY)), CLK_DELAY };/* 100Hz */
 REG clk_reg[] = {
    { HRDATA (CSR, clk_csr, 16) },
@ -180,6 +213,7 @@ REG clk_reg[] = {
    { DRDATA (POLL, tmr_poll, 24), REG_NZ + PV_LEFT + REG_HRO },
    { DRDATA (TPS, clk_tps, 8), REG_NZ + PV_LEFT },
 #if defined (SIM_ASYNCH_IO)
    { DRDATA (ASYNCH, sim_asynch_enabled, 1), PV_LEFT },
    { DRDATA (LATENCY, sim_asynch_latency, 32), PV_LEFT },
    { DRDATA (INST_LATENCY, sim_asynch_inst_latency, 32), PV_LEFT },
 #endif
@ -193,16 +227,15 @@ MTAB clk_mod[] = {
 DEVICE clk_dev = {
    "CLK", &clk_unit, clk_reg, clk_mod,
-    1, 0, 0, 0, 0, 0,
+    1, 0, 8, 1, 0, 0,
    NULL, NULL, &clk_reset,
-    NULL, NULL, NULL,
+    NULL, &clk_attach, &clk_detach,
    &clk_dib, 0
    };
 /* Clock and terminal MxPR routines
   iccs_rd/wr   interval timer
   todr_rd/wr   time of year clock
   rxcs_rd/wr   input control/status
   rxdb_rd      input buffer
   txcs_rd/wr   output control/status
@ -214,11 +247,6 @@ int32 iccs_rd (void)
 return (clk_csr & CLKCSR_IMP);
 }
 int32 todr_rd (void)
 {
 return todr_reg;
 }
 int32 rxcs_rd (void)
 {
 return (tti_csr & TTICSR_IMP);
@ -247,14 +275,6 @@ clk_csr = (clk_csr & ~CLKCSR_RW) | (data & CLKCSR_RW);
 return;
 }
 void todr_wr (int32 data)
 {
 todr_reg = data;
 if (data)
    todr_blow = 0;
 return;
 }
 void rxcs_wr (int32 data)
 {
 if ((data & CSR_IE) == 0)
@ -357,7 +377,8 @@ return SCPE_OK;
   clk_svc      process event (clock tick)
   clk_reset    process reset
-   todr_powerup powerup for TODR (get date from system)
+   todr_rd/wr   time of year clock
   todr_resync  powerup for TODR (get date from system)
 */
 t_stat clk_svc (UNIT *uptr)
@ -370,8 +391,8 @@ t = sim_rtcn_calb (clk_tps, TMR_CLK);                   /* calibrate clock */
 sim_activate (&clk_unit, t);                            /* reactivate unit */
 tmr_poll = t;                                           /* set tmr poll */
 tmxr_poll = t * TMXR_MULT;                              /* set mux poll */
-if (!todr_blow)                                         /* incr TODR */
+if (!todr_blow && todr_reg)                             /* if running? */
-    todr_reg = todr_reg + 1;
+    todr_reg = todr_reg + 1;                            /* incr TODR */
 return SCPE_OK;
 }
@ -385,11 +406,65 @@ t = sim_is_active (&clk_unit);
 return (t? t - 1: wait);
 }
 int32 todr_rd (void)
 {
 TOY *toy = (TOY *)clk_unit.filebuf;
 struct timespec base, now, val;
 if ((fault_PC&0xFFFE0000) == 0x20040000)                /* running from ROM? */
    return todr_reg;                                    /* return counted value for ROM diags */
 if (0 == todr_reg)                                      /* clock running? */
    return todr_reg;
 /* Maximum number of seconds which can be represented as 10ms ticks 
   in the 32bit TODR.  This is the 33bit value 0x100000000/100 to get seconds */
 #define TOY_MAX_SECS (0x40000000/25)
 clock_gettime(CLOCK_REALTIME, &now);                    /* get curr time */
 base.tv_sec = toy->toy_gmtbase;
 base.tv_nsec = toy->toy_gmtbasemsec * 1000000;
 sim_timespec_diff (&val, &now, &base);
 if (val.tv_sec >= TOY_MAX_SECS)                         /* todr overflowed? */
    return todr_reg = 0;                                /* stop counting */
 return (int32)(val.tv_sec*100 + val.tv_nsec/10000000);  /* 100hz Clock Ticks */
 }
 void todr_wr (int32 data)
 {
 TOY *toy = (TOY *)clk_unit.filebuf;
 struct timespec now, val, base;
 /* Save the GMT time when set value was 0 to record the base for future 
   read operations in "battery backed-up" state */
 if (-1 == clock_gettime(CLOCK_REALTIME, &now))          /* get curr time */
    return;                                             /* error? */
 val.tv_sec = ((uint32)data) / 100;
 val.tv_nsec = (((uint32)data) % 100) * 10000000;
 sim_timespec_diff (&base, &now, &val);                  /* base = now - data */
 toy->toy_gmtbase = base.tv_sec;
 toy->toy_gmtbasemsec = base.tv_nsec/1000000;
 todr_reg = data;
 if (data)
    todr_blow = 0;
 }
 /* TODR resync routine */
 t_stat todr_resync (void)
 {
-uint32 base;
+TOY *toy = (TOY *)clk_unit.filebuf;
 if (clk_unit.flags & UNIT_ATT) {                        /* Attached means behave like real VAX780 */
    if (!toy->toy_gmtbase)                              /* Never set? */
        todr_wr (0);                                    /* Start ticking from 0 */
    }
 else {                                                  /* Not-Attached means */
    uint32 base;                                        /* behave like simh VMS default */
    time_t curr;
    struct tm *ctm;
@ -403,8 +478,8 @@ base = (((((ctm->tm_yday * 24) +                        /* sec since 1-Jan */
            ctm->tm_hour) * 60) +
            ctm->tm_min) * 60) +
            ctm->tm_sec;
-todr_reg = (base * 100) + 0x10000000;                   /* cvt to VAX form */
+    todr_wr ((base * 100) + 0x10000000);                /* use VMS form */
-todr_blow = 0;
+    }
 return SCPE_OK;
 }
@ -414,13 +489,46 @@ t_stat clk_reset (DEVICE *dptr)
 {
 int32 t;
 todr_resync ();                                         /* resync clock */
 clk_csr = 0;
 CLR_INT (CLK);
 t = sim_rtcn_init (clk_unit.wait, TMR_CLK);             /* init timer */
 sim_activate_abs (&clk_unit, t);                        /* activate unit */
 tmr_poll = t;                                           /* set tmr poll */
 tmxr_poll = t * TMXR_MULT;                              /* set mux poll */
 if (clk_unit.filebuf == NULL) {                         /* make sure the TODR is initialized */
    clk_unit.filebuf = calloc(sizeof(TOY), 1);
    if (clk_unit.filebuf == NULL)
        return SCPE_MEM;
    todr_resync ();
    }
 return SCPE_OK;
 }
 /* CLK attach */
 t_stat clk_attach (UNIT *uptr, char *cptr)
 {
 t_stat r;
 uptr->flags = uptr->flags | (UNIT_ATTABLE | UNIT_BUFABLE);
 memset (uptr->filebuf, 0, (size_t)uptr->capac);
 r = attach_unit (uptr, cptr);
 if (r != SCPE_OK)
    uptr->flags = uptr->flags & ~(UNIT_ATTABLE | UNIT_BUFABLE);
 else
    uptr->hwmark = (uint32) uptr->capac;
 return r;
 }
 /* CLK detach */
 t_stat clk_detach (UNIT *uptr)
 {
 t_stat r;
 r = detach_unit (uptr);
 if ((uptr->flags & UNIT_ATT) == 0)
    uptr->flags = uptr->flags & ~(UNIT_ATTABLE | UNIT_BUFABLE);
 return r;
 }
--- a/Projects/VAX730.vcproj
+++ b/Projects/VAX730.vcproj
@ -134,7 +134,7 @@
 				FavorSizeOrSpeed="1"
 				OmitFramePointers="true"
 				AdditionalIncludeDirectories="./;../;../VAX/;../pdp11/;../../winpcap/Wpdpack/Include;&quot;../../pthreads/Pre-built.2/include&quot;"
-				PreprocessorDefinitions="USE_INT64;USE_ADDR64;VM_VAX;VAX_730;USE_SHARED;_CRT_SECURE_NO_WARNINGS;USE_READER_THREAD"
+				PreprocessorDefinitions="USE_INT64;USE_ADDR64;VM_VAX;VAX_730;USE_SHARED;_CRT_SECURE_NO_WARNINGS;USE_READER_THREAD;SIM_ASYNCH_IO"
 				StringPooling="true"
 				RuntimeLibrary="0"
 				EnableFunctionLevelLinking="true"
--- a/Projects/VAX780.vcproj
+++ b/Projects/VAX780.vcproj
@ -27,7 +27,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Build Dependent ROM include File(s)"
-				CommandLine="pushd ..&#x0D;&#x0A;$(TargetDir)BuildROMs&#x0D;&#x0A;popd"
+				CommandLine="pushd ..&#x0D;&#x0A;$(TargetDir)BuildROMs&#x0D;&#x0A;popd&#x0D;&#x0A;"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@ -112,7 +112,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Build Dependent ROM include File(s)"
-				CommandLine="pushd ..&#x0D;&#x0A;$(TargetDir)BuildROMs&#x0D;&#x0A;popd"
+				CommandLine="pushd ..&#x0D;&#x0A;$(TargetDir)BuildROMs&#x0D;&#x0A;popd&#x0D;&#x0A;"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@ -134,7 +134,7 @@
 				FavorSizeOrSpeed="1"
 				OmitFramePointers="true"
 				AdditionalIncludeDirectories="./;../;../VAX/;../pdp11/;../../winpcap/Wpdpack/Include;&quot;../../pthreads/Pre-built.2/include&quot;"
-				PreprocessorDefinitions="USE_INT64;USE_ADDR64;VM_VAX;VAX_780;USE_SHARED;_CRT_SECURE_NO_WARNINGS;USE_READER_THREAD"
+				PreprocessorDefinitions="USE_INT64;USE_ADDR64;VM_VAX;VAX_780;USE_SHARED;_CRT_SECURE_NO_WARNINGS;USE_READER_THREAD;SIM_ASYNCH_IO"
 				StringPooling="true"
 				RuntimeLibrary="0"
 				EnableFunctionLevelLinking="true"
--- a/descrip.mms
+++ b/descrip.mms
@ -57,8 +57,8 @@
 #
 #        MMK/MACRO=(NOASYNCH=1)
 #
-# On AXP the AXP PCAP components are built and used to provide network 
+# On AXP and IA64 the VMS PCAP components are built and used to provide 
-# support for the VAX and PDP11 simulators.
+# network support for the VAX and PDP11 simulators.
 #
 # The AXP PCAP components can only be built using a version of the 
 # DEC/Compaq/HP Compiler version V6.5-001 or later.  To build using an
--- a/32
+++ b/32
@ -13,6 +13,7 @@
 #
 ifeq ($(WIN32),)
  #*nix Environments (&& cygwin)
  GCC = gcc
  ifeq (SunOS,$(shell uname))
    TEST = /bin/test
  else
@ -23,16 +24,20 @@ ifeq ($(WIN32),)
  else
    ifeq (Linux,$(shell uname))
      LIBEXT = so
    else
      ifeq (SunOS,$(shell uname))
        LIBEXT = so
      else
        LIBEXT = a
      endif
    endif
  endif
  OS_CCDEFS = -D_GNU_SOURCE
-  ifeq (libm,$(shell if $(TEST) -e /usr/lib/libm.$(LIBEXT); then echo libm; fi))
+  ifeq (libm,$(shell if $(TEST) -e /usr/lib/libm.$(LIBEXT) -o -e /usr/lib64/libm.$(LIBEXT); then echo libm; fi))
    OS_LDFLAGS += -lm
  endif
  ifeq (SunOS,$(shell uname))
-    OS_CCDEFS += -I/opt/sfw/include
+    OS_CCDEFS += -I/opt/sfw/include -DSIM_ASYNCH_IO -DUSE_READER_THREAD 
    OS_LDFLAGS += -lsocket -lnsl -lrt -lm -lpthread -L/opt/sfw/lib -R/opt/sfw/lib
    endif
  ifeq (cygwin,$(findstring cygwin,$(OSTYPE)))
@ -46,29 +51,41 @@ ifeq ($(WIN32),)
    OS_LDFLAGS += -lpthread 
  endif
  ifeq (readline,$(shell if $(TEST) -e /usr/lib/libreadline.$(LIBEXT) -o -e /usr/lib64/libreadline.$(LIBEXT) -o -e /opt/sfw/lib/libreadline.a; then echo readline; fi))
-    ifeq (readline_h,$(shell if $(TEST) -e /usr/include/readline/readline.h -o -e /usr/include/readline.h; then echo readline_h; fi))
+    ifeq (readline_h,$(shell if $(TEST) -e /usr/include/readline/readline.h -o -e /usr/include/readline.h -o -e /opt/sfw/include/readline/readline.h; then echo readline_h; fi))
      # Use Locally installed and available readline support
      ifeq (ncurses,$(shell if $(TEST) -e /usr/lib/libncurses.$(LIBEXT) -o -e /opt/sfw/lib/libncurses.a; then echo ncurses; fi))
        OS_CCDEFS += -DHAVE_READLINE 
        OS_LDFLAGS += -lreadline -lncurses
      else
        ifeq (curses,$(shell if $(TEST) -e /usr/lib/libcurses.$(LIBEXT); then echo curses; fi))
          OS_CCDEFS += -DHAVE_READLINE 
          OS_LDFLAGS += -lreadline -lcurses
        else
          ifeq (solaris_readline,$(shell if $(TEST) ! -e /opt/sfw/lib/libreadline.a; then echo solaris_readline; fi))
            OS_CCDEFS += -DHAVE_READLINE 
            OS_LDFLAGS += -lreadline 
          endif
        endif
      endif
    endif
  endif
  ifeq (pcap,$(shell if $(TEST) -e /usr/include/pcap.h -o -e /opt/sfw/include/pcap.h; then echo pcap; fi))
    # Use Locally installed and available pcap support
    NETWORK_CCDEFS = -DUSE_NETWORK
    NETWORK_LDFLAGS = -lpcap
  endif
  ifeq (vde,$(shell if $(TEST) -e /usr/include/libvdeplug.h -a \( -e /usr/lib/libvdeplug.$(LIBEXT) -o -e /usr/lib64/libvdeplug.$(LIBEXT) \); then echo vde; fi))
    # Provide support for vde networking
    NETWORK_CCDEFS += -DUSE_VDE_NETWORK
    NETWORK_LDFLAGS += -lvdeplug
  endif
  ifeq (tuntap,$(shell if $(TEST) -e /usr/include/linux/if_tun.h; then echo tuntap; fi))
    # Provide support for Tap networking on Linux
-    NETWORK_TAP_CCDEFS = -DUSE_TAP_NETWORK
+    NETWORK_CCDEFS += -DUSE_TAP_NETWORK
  endif
-  ifeq (bsdtuntap,$(shell if $(TEST) -e /usr/include/net/if_tun.h; then echo bsdtuntap; fi))
+  ifeq (bsdtuntap,$(shell if $(TEST) -e /usr/include/net/if_tun.h -o -e /Library/Extensions/tap.kext; then echo bsdtuntap; fi))
    # Provide support for Tap networking
-    NETWORK_TAP_CCDEFS = -DUSE_TAP_NETWORK -DUSE_BSDTUNTAP
+    NETWORK_CCDEFS += -DUSE_TAP_NETWORK -DUSE_BSDTUNTAP
  endif
  ifneq (binexists,$(shell if $(TEST) -e BIN; then echo binexists; fi))
    MKDIRBIN = if $(TEST) ! -e BIN; then mkdir BIN; fi
@ -79,6 +96,7 @@ ifeq ($(WIN32),)
  endif
 else
  #Win32 Environments (via MinGW32)
  GCC = gcc
  GCC_Path := $(dir $(shell where gcc.exe))
  ifeq ($(NOASYNCH),)
    ifeq (pthreads,$(shell if exist ..\pthreads\Pre-built.2\include\pthread.h echo pthreads))
@ -119,7 +137,7 @@ else
 endif
-CC = gcc -std=c99 -U__STRICT_ANSI__ -g -I . $(NETWORK_CCDEFS) $(NETWORK_TAP_CCDEFS) $(OS_CCDEFS) $(ROMS_OPT)
+CC = $(GCC) -std=c99 -U__STRICT_ANSI__ -g -I . $(NETWORK_CCDEFS) $(OS_CCDEFS) $(ROMS_OPT)
 LDFLAGS = $(OS_LDFLAGS) $(NETWORK_LDFLAGS) 
 #
--- a/scp.c
+++ b/scp.c
@ -23,6 +23,17 @@
   used in advertising or otherwise to promote the sale, use or other dealings
   in this Software without prior written authorization from Robert M Supnik.
   25-Sep-11    MP      Added the ability for a simulator built with 
                        SIM_ASYNCH_IO to change whether I/O is actually done
                        asynchronously by the new scp command SET ASYNCH and 
                        SET NOASYNCH
   22-Sep-11    MP      Added signal catching of SIGHUP and SIGTERM to cause 
                        simulator STOP.  This allows an externally signalled
                        event (i.e. system shutdown, or logoff) to signal a
                        running simulator of these events and to allow 
                        reasonable actions to be taken.  This will facilitate 
                        running a simulator as a 'service' on *nix platforms, 
                        given a sufficiently flexible simulator .ini file.  
   20-Apr-11    MP      Added expansion of %STATUS% and %TSTATUS% in do command
                        arguments.  STATUS is the numeric value of the last 
                        command error status and TSTATUS is the text message
@ -271,6 +282,7 @@ pthread_mutex_t sim_asynch_lock = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t sim_asynch_wake = PTHREAD_COND_INITIALIZER;
 pthread_t sim_asynch_main_threadid;
 struct sim_unit *sim_asynch_queue = NULL;
 t_bool sim_asynch_enabled = TRUE;
 int32 sim_asynch_check;
 int32 sim_asynch_latency = 4000;      /* 4 usec interrupt latency */
 int32 sim_asynch_inst_latency = 20;   /* assume 5 mip simulator */
@ -387,6 +399,7 @@ t_stat dep_addr (int32 flag, char *cptr, t_addr addr, DEVICE *dptr,
 t_stat step_svc (UNIT *ptr);
 void sub_args (char *instr, char *tmpbuf, int32 maxstr, char *do_arg[]);
 t_stat set_on (int32 flag, char *cptr);
 t_stat set_asynch (int32 flag, char *cptr);
 /* Global data */
@ -603,8 +616,11 @@ static CTAB cmd_table[] = {
      "set console NODEBUG      disable console debugging\n"
      "set break <list>         set breakpoints\n"
      "set nobreak <list>       clear breakpoints\n"
-      "set throttle x{M|K|%%}   set simulation rate\n"
+      "set throttle {x{M|K|%}}|{x/t}\n"
      "                         set simulation rate\n"
      "set nothrottle           set simulation rate to maximum\n"
      "set asynch               enable asynchronous I/O\n"
      "set noasynch             disable asynchronous I/O\n"
      "set <dev> OCT|DEC|HEX    set device display radix\n"
      "set <dev> ENABLED        enable device\n"
      "set <dev> DISABLED       disable device\n"
@ -628,6 +644,7 @@ static CTAB cmd_table[] = {
      "sh{ow} q{ueue}           show event queue\n"  
      "sh{ow} ti{me}            show simulated time\n"
      "sh{ow} th{rottle}        show simulation rate\n" 
      "sh{ow} a{synch}          show asynchronouse I/O state\n" 
      "sh{ow} ve{rsion}         show simulator version\n" 
      "sh{ow} <dev> RADIX       show device display radix\n"
      "sh{ow} <dev> DEBUG       show device debug flags\n"
@ -1006,13 +1023,6 @@ do {
         (cmdp->action != &on_cmd) &&
         (cmdp->action != &echo_cmd)))
        sim_last_cmd_stat = stat;                       /* save command error status */
    staying = (stat != SCPE_EXIT) &&                    /* decide if staying */
              (stat != SCPE_AFAIL) &&
              (!errabort || (stat < SCPE_BASE) || (stat == SCPE_STEP));
    if ((stat == SCPE_AFAIL) &&                         /* handle special case AFAIL */
        sim_on_check[sim_do_depth] &&                   /* and use trap action if defined */
        sim_on_actions[sim_do_depth][stat])             /* otherwise exit */
        staying = TRUE;
    if ((stat >= SCPE_BASE) && (stat != SCPE_EXIT) &&   /* error from cmd? */
        (stat != SCPE_STEP)) {
        if (!echo && !sim_quiet &&                      /* report if not echoing */
@ -1023,8 +1033,23 @@ do {
            }
        stat = stat & ~SCPE_DOFAILED;                   /* remove possible flag */
        }
    switch (stat) {
        case SCPE_OK:
        case SCPE_STEP:
            break;
        case SCPE_AFAIL:
            staying = (sim_on_check[sim_do_depth] &&        /* if trap action defined */
                       sim_on_actions[sim_do_depth][stat]); /* use it, otherwise exit */
            break;
        case SCPE_EXIT:
            staying = FALSE;
            break;
        default:
            staying = sim_on_check[sim_do_depth];
            break;
        }
    if ((staying || !interactive) &&                    /* report error if staying */
-        (stat >= SCPE_BASE)) {                          /* or in cmdline file */
+        (stat >= SCPE_BASE) && !isdo) {                 /* or in cmdline file */
        printf ("%s\n", sim_error_text (stat));
        if (sim_log)
            fprintf (sim_log, "%s\n", sim_error_text (stat));
@ -1033,7 +1058,7 @@ do {
        (sim_on_check[sim_do_depth]) && 
        (stat != SCPE_OK) &&
        (stat != SCPE_STEP))
-        if (sim_on_actions[sim_do_depth][stat])
+        if ((stat <= SCPE_MAX_ERR) && sim_on_actions[sim_do_depth][stat])
            sim_brk_act[sim_do_depth] = sim_on_actions[sim_do_depth][stat];
        else
            sim_brk_act[sim_do_depth] = sim_on_actions[sim_do_depth][0];
@ -1281,6 +1306,61 @@ if ((sim_do_depth != 0) &&
 return SCPE_OK;
 }
 /* Set asynch/noasynch routine */
 t_stat sim_set_asynch (int32 flag, char *cptr)
 {
 if (cptr && (*cptr != 0))                               /* now eol? */
    return SCPE_2MARG;
 #ifdef SIM_ASYNCH_IO
 if (flag == sim_asynch_enabled)                         /* already set correctly? */
    return SCPE_OK;
 sim_asynch_enabled = flag;
 if (1) {
    uint32 i, j;
    DEVICE *dptr;
    UNIT *uptr;
    /* Call unit flush routines to report asynch status change to device layer */
    for (i = 1; (dptr = sim_devices[i]) != NULL; i++) { /* flush attached files */
        for (j = 0; j < dptr->numunits; j++) {          /* if not buffered in mem */
            uptr = dptr->units + j;
            if ((uptr->flags & UNIT_ATT) &&             /* attached, */
                !(uptr->flags & UNIT_BUF) &&            /* not buffered, */
                (uptr->fileref))                        /* real file, */
                if (uptr->io_flush)                     /* unit specific flush routine */
                    uptr->io_flush (uptr);
            }
        }
    }
 if (!sim_quiet)
    printf ("Asynchronous I/O %sabled\n", sim_asynch_enabled ? "en" : "dis");
 if (sim_log)
    fprintf (sim_log, "Asynchronous I/O %sabled\n", sim_asynch_enabled ? "en" : "dis");
 return SCPE_OK;
 #else
 if (!sim_quiet)
    printf ("Asynchronous I/O is not available in this simulator\n");
 if (sim_log)
    fprintf (sim_log, "Asynchronous I/O is not available in this simulator\n");
 return SCPE_NOFNC;
 #endif
 }
 /* Show asynch routine */
 t_stat sim_show_asynch (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, char *cptr)
 {
 if (cptr && (*cptr != 0))
    return SCPE_2MARG;
 #ifdef SIM_ASYNCH_IO
 fprintf (st, "Asynchronous I/O is %sabled\n", (sim_asynch_enabled) ? "en" : "dis");
 #else
 fprintf (st, "Asynchronous I/O is not available in this simulator\n");
 #endif
 return SCPE_OK;
 }
 /* Set command */
 t_stat set_cmd (int32 flag, char *cptr)
@ -1305,6 +1385,8 @@ static CTAB set_glob_tab[] = {
    { "NODEBUG", &sim_set_deboff, 0 },                  /* deprecated */
    { "THROTTLE", &sim_set_throt, 1 },
    { "NOTHROTTLE", &sim_set_throt, 0 },
    { "ASYNCH", &sim_set_asynch, 1 },
    { "NOASYNCH", &sim_set_asynch, 0 },
    { "ON", &set_on, 1 },
    { "NOON", &set_on, 0 },
    { NULL, NULL, 0 }
@ -1570,6 +1652,7 @@ static SHTAB show_glob_tab[] = {
    { "TELNET", &sim_show_telnet, 0 },                  /* deprecated */
    { "DEBUG", &sim_show_debug, 0 },                    /* deprecated */
    { "THROTTLE", &sim_show_throt, 0 },
    { "ASYNCH", &sim_show_asynch, 0 },
    { "ON", &show_on, 0 },
    { NULL, NULL, 0 }
    };
@ -2879,6 +2962,8 @@ for (j=0, r = SCPE_OK; j<attcnt; j++) {
        dptr = find_dev_from_unit (attunits[j]);
        sim_switches = attswitches[j];
        r = scp_attach_unit (dptr, attunits[j], attnames[j]);/* reattach unit */
        if (r != SCPE_OK)
            printf ("Error Attaching %s to %s\n", sim_dname (dptr), attnames[j]);
        }
    free (attnames[j]);
    }
--- a/sim_BuildROMs.c
+++ b/sim_BuildROMs.c
@ -130,7 +130,7 @@ fprintf (iFile, "#define ROM_%s_H 0\n", rom_array_name);
 fprintf (iFile, "/*\n");
 fprintf (iFile, "   %s         produced at %s", include_filename, ctime(&now));
 fprintf (iFile, "   from %s which was last modified at %s", rom_filename, ctime(&statb.st_mtime));
-fprintf (iFile, "   file size: %d (0x%X)\n", statb.st_size, statb.st_size);
+fprintf (iFile, "   file size: %d (0x%X)\n", (int)statb.st_size, (int)statb.st_size);
 fprintf (iFile, "*/\n");
 fprintf (iFile, "unsigned char %s[] = {", rom_array_name);
 for (bytes_written=0;bytes_written<statb.st_size; ++bytes_written) {
--- a/sim_console.c
+++ b/sim_console.c
@ -424,7 +424,8 @@ while (*cptr != 0) {                                    /* do all mods */
        *cvptr++ = 0;
    get_glyph (gbuf, gbuf, 0);                          /* modifier to UC */
    if (isdigit (*gbuf)) {
-        if (sim_con_tmxr.master) return SCPE_ALATT;     /* already open? */
+        if (sim_con_tmxr.master)                        /* already open? */
            sim_set_notelnet (0, NULL);                 /* close first */
        return tmxr_open_master (&sim_con_tmxr, gbuf);  /* open master socket */
        }
    else
@ -633,8 +634,12 @@ if (sim_con_ldsc.conn || sim_con_ldsc.txbfd) {          /* connected or buffered
    tmxr_poll_rx (&sim_con_tmxr);                       /* poll (check disconn) */
    if (sim_con_ldsc.conn || sim_con_ldsc.txbfd) {      /* still connected? */
        if (!sim_con_ldsc.conn) {
-            printf ("Running with Buffered Console\n"); /* print transition */
+            printf ("Running with Buffered Console\r\n"); /* print transition */
            fflush (stdout);
            if (sim_log) {                              /* log file? */
                fprintf (sim_log, "Running with Buffered Console\n");
                fflush (sim_log);
                }
            }
        return SCPE_OK;
        }
@ -643,8 +648,12 @@ for (i = 0; i < sec; i++) {                             /* loop */
    if (tmxr_poll_conn (&sim_con_tmxr) >= 0) {          /* poll connect */
        sim_con_ldsc.rcve = 1;                          /* rcv enabled */
        if (i) {                                        /* if delayed */
-            printf ("Running\n");                       /* print transition */
+            printf ("Running\r\n");                       /* print transition */
            fflush (stdout);
            if (sim_log) {                              /* log file? */
                fprintf (sim_log, "Running\n");
                fflush (sim_log);
                }
            }
        return SCPE_OK;                                 /* ready to proceed */
        }
@ -652,8 +661,12 @@ for (i = 0; i < sec; i++) {                             /* loop */
    if ((c == SCPE_STOP) || stop_cpu)
        return SCPE_STOP;
    if ((i % 10) == 0) {                                /* Status every 10 sec */
-        printf ("Waiting for console Telnet connection\n");
+        printf ("Waiting for console Telnet connection\r\n");
        fflush (stdout);
        if (sim_log) {                              /* log file? */
            fprintf (sim_log, "Waiting for console Telnet connection\n");
            fflush (sim_log);
            }
        }
    sim_os_sleep (1);                                   /* wait 1 second */
    }
--- a/sim_defs.h
+++ b/sim_defs.h
@ -565,6 +565,7 @@ extern pthread_cond_t sim_asynch_wake;
 extern pthread_t sim_asynch_main_threadid;
 extern struct sim_unit *sim_asynch_queue;
 extern t_bool sim_idle_wait;
 extern t_bool sim_asynch_enabled;
 extern int32 sim_asynch_check;
 extern int32 sim_asynch_latency;
 extern int32 sim_asynch_inst_latency;
--- a/sim_disk.c
+++ b/sim_disk.c
@ -408,8 +408,9 @@ return SCPE_NOFNC;
 struct disk_context *ctx = (struct disk_context *)uptr->disk_ctx;
 pthread_attr_t attr;
-ctx->asynch_io = 1;
+ctx->asynch_io = sim_asynch_enabled;
 ctx->asynch_io_latency = latency;
 if (ctx->asynch_io) {
    pthread_mutex_init (&ctx->io_lock, NULL);
    pthread_cond_init (&ctx->io_cond, NULL);
    pthread_attr_init(&attr);
@ -417,6 +418,7 @@ pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
    pthread_create (&ctx->io_thread, &attr, _disk_io, (void *)uptr);
    pthread_attr_destroy(&attr);
    uptr->a_check_completion = _disk_completion_dispatch;
    }
 #endif
 return SCPE_OK;
 }
@ -723,6 +725,7 @@ uint32 f = DK_GET_FMT (uptr);
 #if defined (SIM_ASYNCH_IO)
 sim_disk_clr_async (uptr);
 if (sim_asynch_enabled)
    sim_disk_set_async (uptr, 0);
 #endif
 switch (f) {                                            /* case on format */
@ -1332,7 +1335,7 @@ if (strchr (openmode, 'r'))
    DesiredAccess |= GENERIC_READ;
 if (strchr (openmode, 'w') || strchr (openmode, '+'))
    DesiredAccess |= GENERIC_WRITE;
-Handle = CreateFileA (rawdevicename, DesiredAccess, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_RANDOM_ACCESS, NULL);
+Handle = CreateFileA (rawdevicename, DesiredAccess, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_RANDOM_ACCESS|FILE_FLAG_WRITE_THROUGH, NULL);
 if (Handle == INVALID_HANDLE_VALUE) {
    _set_errno_from_status (GetLastError ());
    return NULL;
@ -1418,7 +1421,10 @@ static t_stat sim_os_disk_unload_raw (FILE *Disk)
 {
 #ifdef IOCTL_STORAGE_EJECT_MEDIA
 DWORD BytesReturned;
 uint32 Removable = FALSE;
 sim_os_disk_info_raw (Disk, NULL, &Removable);
 if (Removable) {
    if (!DeviceIoControl((HANDLE)Disk,                  /* handle to disk */
                         IOCTL_STORAGE_EJECT_MEDIA,     /* dwIoControlCode */
                         NULL,                          /* lpInBuffer */
@ -1430,6 +1436,7 @@ if (!DeviceIoControl((HANDLE)Disk,                      /* handle to disk */
        _set_errno_from_status (GetLastError ());
        return SCPE_IOERR;
        }
    }
 return SCPE_OK;
 #else
 return SCPE_NOFNC;
@ -1440,7 +1447,10 @@ static t_bool sim_os_disk_isavailable_raw (FILE *Disk)
 {
 #ifdef IOCTL_STORAGE_EJECT_MEDIA
 DWORD BytesReturned;
 uint32 Removable = FALSE;
 sim_os_disk_info_raw (Disk, NULL, &Removable);
 if (Removable) {
    if (!DeviceIoControl((HANDLE)Disk,                  /* handle to disk */
                         IOCTL_STORAGE_CHECK_VERIFY,    /* dwIoControlCode */
                         NULL,                          /* lpInBuffer */
@ -1452,6 +1462,7 @@ if (!DeviceIoControl((HANDLE)Disk,                      /* handle to disk */
        _set_errno_from_status (GetLastError ());
        return FALSE;
        }
    }
 #endif
 return TRUE;
 }
@ -2646,6 +2657,7 @@ if (SizeInBytes > ((uint64)(1024*1024*1024))*2040) {
    }
 if (File = sim_fopen (szVHDPath, "rb")) {
    fclose (File);
    File = NULL;
    Status = EEXIST;
    goto Cleanup_Return;
    }
@ -2773,6 +2785,7 @@ if (WriteFilePosition(File,
 Cleanup_Return:
 free (BAT);
 if (File)
    fclose (File);
 if (Status) {
    if (Status != EEXIST)
--- a/sim_ether.c
+++ b/sim_ether.c
@ -138,6 +138,15 @@
                      at open time.  This functionality is only useful/needed 
                      on *nix platforms since native sharing of Windows NIC 
                      devices works with no external magic.
  USE_VDE_NETWORK   - Specifies that support for vde networking should be 
                      included.  This can be leveraged, along with OS bridging
                      capabilities to share a single LAN interface.  It also
                      can allow a simulator to have useful networking 
                      functionality when running without root access.  This 
                      allows device names of the form vde:/tmp/switch to be 
                      specified at open time.  This functionality is only 
                      available on *nix platforms since the vde api isn't 
                      available on Windows.
  NEED_PCAP_SENDPACKET
                    - Specifies that you are using an older version of libpcap
@ -151,6 +160,11 @@
  Modification history:
  30-Oct-11  MP   Added support for vde (Virtual Distributed Ethernet) networking
  29-Oct-11  MP   Added support for integrated Tap networking interfaces on OSX
  12-Aug-11  MP   Cleaned up payload length determination
                  Fixed race condition detecting reflections when threaded 
                  reading and writing is enabled
  18-Apr-11  MP   Fixed race condition with self loopback packets in 
                  multithreaded environments
  09-Jan-11  MP   Fixed missing crc data when USE_READER_THREAD is defined and 
@ -787,12 +801,16 @@ void eth_show_dev (FILE* st, ETH_DEV* dev)
 #elif defined(USE_BSDTUNTAP)
 #include <sys/types.h>
 #include <net/if_types.h>
-#include <net/if_tun.h>
+#include <net/if.h>
 #else /* We don't know how to do this on the current platform */
 #undef USE_TAP_NETWORK
 #endif
 #endif /* USE_TAP_NETWORK */
 #ifdef USE_VDE_NETWORK
 #include <libvdeplug.h>
 #endif /* USE_VDE_NETWORK */
 /* Allows windows to look up user-defined adapter names */
 #if defined(_WIN32)
 #include <winreg.h>
@ -1092,10 +1110,12 @@ static void eth_get_nic_hw_addr(ETH_DEV* dev, char *devname)
  if (!pcap_mac_if_win32(devname, (UCHAR *)&dev->host_nic_phy_hw_addr))
    dev->have_host_nic_phy_addr = 1;
 #elif !defined (__VMS)
-{
+  if (1) {
    char command[1024];
    FILE *f;
    if (0 == strncmp("vde:", devname, 4))
      return;
    memset(command, 0, sizeof(command));
    snprintf(command, sizeof(command)-1, "ifconfig %s | grep [0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F] >NIC.hwaddr", devname);
    system(command);
@ -1148,16 +1168,24 @@ int sched_policy;
 struct sched_param sched_priority;
 #if defined (_WIN32)
 HANDLE hWait = pcap_getevent ((pcap_t*)dev->handle);
-#endif
+#else
 #if defined (MUST_DO_SELECT)
 struct timeval timeout;
 int sel_ret;
-int pcap_fd;
+int do_select = 0;
 int select_fd;
-if (dev->pcap_mode)
+switch (dev->eth_api) {
-  pcap_fd = pcap_get_selectable_fd((pcap_t *)dev->handle);
+  case ETH_API_PCAP:
-else
+#if defined (MUST_DO_SELECT)
-  pcap_fd = dev->fd_handle;
+    do_select = 1;
    select_fd = pcap_get_selectable_fd((pcap_t *)dev->handle);
 #endif
    break;
  case ETH_API_TAP:
  case ETH_API_VDE:
    do_select = 1;
    select_fd = dev->fd_handle;
    break;
  }
 #endif
 sim_debug(dev->dbit, dev->dptr, "Reader Thread Starting\n");
@ -1169,32 +1197,35 @@ else
 ++sched_priority.sched_priority;
 pthread_setschedparam (pthread_self(), sched_policy, &sched_priority);
-  while ((dev->pcap_mode && dev->handle) || dev->fd_handle) {
+while (dev->handle) {
 #if defined (MUST_DO_SELECT)
    fd_set setl;
    FD_ZERO(&setl);
    FD_SET(pcap_fd, &setl);
    timeout.tv_sec = 0;
    timeout.tv_usec = 250*1000;
    sel_ret = select(1+pcap_fd, &setl, NULL, NULL, &timeout);
    if (sel_ret < 0 && errno != EINTR) break;
    if (sel_ret > 0) {
 #else /* !MUST_DO_SELECT */
 #if defined (_WIN32)
  if (WAIT_OBJECT_0 == WaitForSingleObject (hWait, 250)) {
 #else
-    if (1)  {
+  fd_set setl;
-#endif
+  struct timeval timeout;
-#endif /* MUST_DO_SELECT */
+
-      if ((dev->pcap_mode) && (!dev->handle))
+  if (do_select) {
-        break;
+    FD_ZERO(&setl);
-      if ((!dev->pcap_mode) && (!dev->fd_handle))
+    FD_SET(select_fd, &setl);
    timeout.tv_sec = 0;
    timeout.tv_usec = 250*1000;
    sel_ret = select(1+select_fd, &setl, NULL, NULL, &timeout);
    }
  else
    sel_ret = 1;
  if (sel_ret < 0 && errno != EINTR) break;
  if (sel_ret > 0) {
 #endif /* _WIN32 */
    if (!dev->handle)
      break;
    /* dispatch read request queue available packets */
-      if (dev->pcap_mode)
+    switch (dev->eth_api) {
      case ETH_API_PCAP:
        status = pcap_dispatch ((pcap_t*)dev->handle, -1, &_eth_callback, (u_char*)dev);
        break;
 #ifdef USE_TAP_NETWORK
-      else {
+      case ETH_API_TAP:
        if (1) {
          struct pcap_pkthdr header;
          int len;
          u_char buf[ETH_MAX_JUMBO_FRAME];
@ -1205,14 +1236,35 @@ else
            status = 1;
            header.caplen = header.len = len;
            _eth_callback((u_char *)dev, &header, buf);
-        } else {
+            }
          else
            status = 0;
          }
-      }
+        break;
 #endif /* USE_TAP_NETWORK */
 #ifdef USE_VDE_NETWORK
      case ETH_API_VDE:
        if (1) {
          struct pcap_pkthdr header;
          int len;
          u_char buf[ETH_MAX_JUMBO_FRAME];
          memset(&header, 0, sizeof(header));
          len = vde_recv((VDECONN *)dev->handle, buf, sizeof(buf), 0);
          if (len > 0) {
            status = 1;
            header.caplen = header.len = len;
            _eth_callback((u_char *)dev, &header, buf);
            }
          else
            status = 0;
          }
        break;
 #endif /* USE_VDE_NETWORK */
      }
    if ((status > 0) && (dev->asynch_io)) {
      int wakeup_needed;
      pthread_mutex_lock (&dev->lock);
      wakeup_needed = (dev->read_queue.count != 0);
      pthread_mutex_unlock (&dev->lock);
@ -1246,7 +1298,7 @@ struct sched_param sched_priority;
 sim_debug(dev->dbit, dev->dptr, "Writer Thread Starting\n");
 pthread_mutex_lock (&dev->writer_lock);
-  while ((dev->pcap_mode && dev->handle) || dev->fd_handle) {
+while (dev->handle) {
  pthread_cond_wait (&dev->writer_cond, &dev->writer_lock);
  while (request = dev->write_requests) {
    /* Pull buffer off request list */
@ -1330,7 +1382,8 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
  savname = eth_getname(num, temp);
  if (savname == 0) /* didn't translate */
    return SCPE_OPENERR;
-  } else {
+  }
 else {
  /* are they trying to use device description? */
  savname = eth_getname_bydesc(name, temp);
  if (savname == 0) { /* didn't translate */
@ -1343,16 +1396,7 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
 /* attempt to connect device */
 memset(errbuf, 0, sizeof(errbuf));
-  if (strncmp("tap:", savname, 4)) {
+if (0 == strncmp("tap:", savname, 4)) {
    dev->handle = (void*) pcap_open_live(savname, bufsz, ETH_PROMISC, PCAP_READ_TIMEOUT, errbuf);
    if (!dev->handle) { /* can't open device */
      msg = "Eth: pcap_open_live error - %s\r\n";
      printf (msg, errbuf);
      if (sim_log) fprintf (sim_log, msg, errbuf);
      return SCPE_OPENERR;
    }
    dev->pcap_mode = 1;
  } else {
  int  tun = -1;    /* TUN/TAP Socket */
  int  on = 1;
  char dev_name[64] = "";
@ -1374,18 +1418,21 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
    strcpy(ifr.ifr_name, savname+4);
    ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
-      // Send interface requests to TUN/TAP driver.
+    /* Send interface requests to TUN/TAP driver. */
    if (ioctl(tun, TUNSETIFF, &ifr) >= 0) {
      if (ioctl(tun, FIONBIO, &on)) {
        strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
        close(tun);
-        } else {
+        }
      else {
        dev->fd_handle = tun;
        strcpy(savname, ifr.ifr_name);
        }
-      } else
+      }
    else
      strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
-    } else
+    }
  else
    strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
 #elif defined(USE_BSDTUNTAP) && defined(USE_TAP_NETWORK)
  snprintf(dev_name, sizeof(dev_name)-1, "/dev/%s", savname+4);
@ -1395,16 +1442,70 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
    if (ioctl(tun, FIONBIO, &on)) {
      strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
      close(tun);
-      } else {
+      }
    else {
      dev->fd_handle = tun;
      strcpy(savname, savname+4);
      }
-    } else {
+#if defined (__APPLE__)
-      strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
+    if (1) {
      struct ifreq ifr;
      int s;
      memset (&ifr, 0, sizeof(ifr));
      ifr.ifr_addr.sa_family = AF_INET;
      strncpy(ifr.ifr_name, savname+4, sizeof(ifr.ifr_name));
      if ((s = socket(AF_INET, SOCK_DGRAM, 0)) >= 0) {
        if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) >= 0) {
          ifr.ifr_flags |= IFF_UP;
          ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr);
          }
        close(s);
        }
      }
 #endif
    }
  else
    strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
 #else
  strncpy(errbuf, "No support for tap: devices", sizeof(errbuf)-1);
 #endif /* !defined(__linux) && !defined(USE_BSDTUNTAP) */
  if (0 == errbuf[0]) {
    dev->eth_api = ETH_API_TAP;
    dev->handle = (void *)1;  /* Flag used to indicated open */
    }
  }
 else
  if (0 == strncmp("vde:", savname, 4)) {
 #if defined(USE_VDE_NETWORK)
    struct vde_open_args voa;
    memset(&voa, 0, sizeof(voa));
    if (!strcmp(savname, "vde:vdedevice")) {
      msg = "Eth: Must specify actual vde device name (i.e. vde:/tmp/switch)\r\n";
      printf (msg, errbuf);
      if (sim_log) fprintf (sim_log, msg, errbuf);
      return SCPE_OPENERR;
      }
    if (!(dev->handle = (void*) vde_open(savname+4, "simh", &voa)))
      strncpy(errbuf, strerror(errno), sizeof(errbuf)-1);
    else {
      dev->eth_api = ETH_API_VDE;
      dev->fd_handle = vde_datafd((VDECONN*)dev->handle);
      }
 #else
    strncpy(errbuf, "No support for vde: network devices", sizeof(errbuf)-1);
 #endif /* !defined(__linux) && !defined(USE_BSDTUNTAP) */
    }
  else {
    dev->handle = (void*) pcap_open_live(savname, bufsz, ETH_PROMISC, PCAP_READ_TIMEOUT, errbuf);
    if (!dev->handle) { /* can't open device */
      msg = "Eth: pcap_open_live error - %s\r\n";
      printf (msg, errbuf);
      if (sim_log) fprintf (sim_log, msg, errbuf);
      return SCPE_OPENERR;
      }
    dev->eth_api = ETH_API_PCAP;
    }
 if (errbuf[0]) {
  msg = "Eth: open error - %s\r\n";
@ -1430,14 +1531,14 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
 #if !defined(HAS_PCAP_SENDPACKET) && defined (xBSD) && !defined (__APPLE__)
 /* Tell the kernel that the header is fully-formed when it gets it.
   This is required in order to fake the src address. */
-  if (dev->pcap_mode) {
+if (dev->eth_api == ETH_API_PCAP) {
  int one = 1;
  ioctl(pcap_fileno(dev->handle), BIOCSHDRCMPLT, &one);
  }
 #endif /* xBSD */
 #if defined (USE_READER_THREAD)
-  {
+if (1) {
  pthread_attr_t attr;
 #if defined(_WIN32)
@ -1457,7 +1558,7 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
 #else /* !defined (USE_READER_THREAD */
 #ifdef USE_SETNONBLOCK
 /* set ethernet device non-blocking so pcap_dispatch() doesn't hang */
-  if (dev->pcap_mode && (pcap_setnonblock (dev->handle, 1, errbuf) == -1)) {
+if ((dev->eth_api == ETH_API_PCAP) && (pcap_setnonblock (dev->handle, 1, errbuf) == -1)) {
  msg = "Eth: Failed to set non-blocking: %s\r\n";
  printf (msg, errbuf);
  if (sim_log) fprintf (sim_log, msg, errbuf);
@ -1465,7 +1566,7 @@ t_stat eth_open(ETH_DEV* dev, char* name, DEVICE* dptr, uint32 dbit)
 #endif
 #endif /* !defined (USE_READER_THREAD */
 #if defined (__APPLE__)
-  if (1) {
+if (dev->eth_api == ETH_API_PCAP) {
  /* Deliver packets immediately, needed for OS X 10.6.2 and later
   * (Snow-Leopard).
   * See this thread on libpcap and Mac Os X 10.6 Snow Leopard on
@ -1503,7 +1604,6 @@ t_stat eth_close(ETH_DEV* dev)
 pthread_cond_destroy (&dev->writer_cond);
 if (1) {
  struct write_request *buffer;
   while (buffer = dev->write_buffers) {
    dev->write_buffers = buffer->next;
    free(buffer);
@ -1516,12 +1616,21 @@ t_stat eth_close(ETH_DEV* dev)
 ethq_destroy (&dev->read_queue);         /* release FIFO queue */
 #endif
-  if (dev->pcap_mode)
+switch (dev->eth_api) {
  case ETH_API_PCAP:
    pcap_close(pcap);
    break;
 #ifdef USE_TAP_NETWORK
-  else
+  case ETH_API_TAP:
    close(pcap_fd);
    break;
 #endif
 #ifdef USE_VDE_NETWORK
  case ETH_API_VDE:
    vde_close((VDECONN*)pcap);
    break;
 #endif
  }
 printf (msg, dev->name);
 if (sim_log) fprintf (sim_log, msg, dev->name);
@ -1628,13 +1737,28 @@ t_stat _eth_write(ETH_DEV* dev, ETH_PACK* packet, ETH_PCALLBACK routine)
    }
    /* dispatch write request (synchronous; no need to save write info to dev) */
-    if (dev->pcap_mode)
+  switch (dev->eth_api) {
    case ETH_API_PCAP:
      status = pcap_sendpacket((pcap_t*)dev->handle, (u_char*)packet->msg, packet->len);
      break;
 #ifdef USE_TAP_NETWORK
-    else
+    case ETH_API_TAP:
      status = ((packet->len == write(dev->fd_handle, (void *)packet->msg, packet->len)) ? 0 : -1);
      break;
 #endif
-
+#ifdef USE_VDE_NETWORK
    case ETH_API_VDE:
      status = vde_send((VDECONN*)dev->handle, (void *)packet->msg, packet->len, 0);
      if ((status == packet->len) || (status == 0))
        status = 0;
      else
        if ((status == -1) && ((errno == EAGAIN) || (errno == EWOULDBLOCK)))
          status = 0;
        else
          status = 1;
      break;
 #endif
    }
  /* On error, correct loopback bookkeeping */
  if ((status != 0) && loopback_self_frame) {
 #ifdef USE_READER_THREAD
@ -1693,7 +1817,8 @@ t_stat eth_write(ETH_DEV* dev, ETH_PACK* packet, ETH_PCALLBACK routine)
    ++write_queue_size;
    }
  last_request->next = request;
-  } else
+  }
 else
    dev->write_requests = request;
 if (write_queue_size > dev->write_queue_peak)
  dev->write_queue_peak = write_queue_size;
@ -1745,12 +1870,14 @@ _eth_hash_validate(ETH_MAC *MultiCastList, int count, ETH_MULTIHASH hash)
         lhash[0], lhash[1], lhash[2], lhash[3], 
         lhash[4], lhash[5], lhash[6], lhash[7]);
  }
 else {
  printf("Should be: %02X %02X %02X %02X %02X %02X %02X %02X\n", 
         hash[0], hash[1], hash[2], hash[3], 
         hash[4], hash[5], hash[6], hash[7]);
  printf("Was:       %02X %02X %02X %02X %02X %02X %02X %02X\n", 
         lhash[0], lhash[1], lhash[2], lhash[3], 
         lhash[4], lhash[5], lhash[6], lhash[7]);
  }
 return 0;
 }
@ -1983,7 +2110,8 @@ _eth_fix_ip_jumbo_offload(ETH_DEV* dev, const u_char* msg, int len)
      if (payload_len > mtu_payload) {
        ip_flags |= IP_MF_FLAG;
        IP->total_len = htons(((mtu_payload>>3)<<3) + IP_HLEN(IP));
-        } else {
+        }
      else {
        IP->total_len = htons(payload_len + IP_HLEN(IP));
        }
      IP->flags = htons(ip_flags);
@ -1992,7 +2120,8 @@ _eth_fix_ip_jumbo_offload(ETH_DEV* dev, const u_char* msg, int len)
      header.caplen = header.len = 14 + ntohs(IP->total_len);
      eth_packet_trace (dev, ((u_char *)IP)-14, header.len, "reading Datagram fragment");
 #if ETH_MIN_JUMBO_FRAME < ETH_MAX_PACKET
-          { /* Debugging is easier if we read packets directly with pcap
+      if (1) {
        /* Debugging is easier if we read packets directly with pcap
           (i.e. we can use Wireshark to verify packet contents)
           we don't want to do this all the time for 2 reasons:
             1) sending through pcap involves kernel transitions and
@ -2033,7 +2162,8 @@ _eth_fix_ip_jumbo_offload(ETH_DEV* dev, const u_char* msg, int len)
      if (payload_len > mtu_payload) {
        TCP->data_offset_and_flags = htons(orig_tcp_flags&~(TCP_PSH_FLAG|TCP_FIN_FLAG|TCP_RST_FLAG));
        IP->total_len = htons(mtu_payload + IP_HLEN(IP) + TCP_DATA_OFFSET(TCP));
-        } else {
+        }
      else {
        TCP->data_offset_and_flags = htons(orig_tcp_flags);
        IP->total_len = htons(payload_len + IP_HLEN(IP) + TCP_DATA_OFFSET(TCP));
        }
@ -2044,7 +2174,8 @@ _eth_fix_ip_jumbo_offload(ETH_DEV* dev, const u_char* msg, int len)
      header.caplen = header.len = 14 + ntohs(IP->total_len);
      eth_packet_trace_ex (dev, ((u_char *)IP)-14, header.len, "reading TCP segment", 1, dev->dbit);
 #if ETH_MIN_JUMBO_FRAME < ETH_MAX_PACKET
-          { /* Debugging is easier if we read packets directly with pcap
+      if (1) {
        /* Debugging is easier if we read packets directly with pcap
           (i.e. we can use Wireshark to verify packet contents)
           we don't want to do this all the time for 2 reasons:
             1) sending through pcap involves kernel transitions and
@ -2138,19 +2269,27 @@ static void
 _eth_callback(u_char* info, const struct pcap_pkthdr* header, const u_char* data)
 {
 ETH_DEV*  dev = (ETH_DEV*) info;
-#ifdef USE_BPF
+int to_me;
-  int to_me = 1;
+int from_me = 0;
 int i;
 int bpf_used;
 switch (dev->eth_api) {
  case ETH_API_PCAP:
 #ifdef USE_BPF
    bpf_used = 1;
    to_me = 1;
    /* AUTODIN II hash mode? */
    if ((dev->hash_filter) && (data[0] & 0x01) && (!dev->promiscuous) && (!dev->all_multicast))
      to_me = _eth_hash_lookup(dev->hash, data);
-#else /* !USE_BPF */
+    break;
-  int to_me = 0;
+#endif /* USE_BPF */
-  int from_me = 0;
+  case ETH_API_TAP:
-  int i;
+  case ETH_API_VDE:
-
+    bpf_used = 0;
    to_me = 0;
    eth_packet_trace (dev, data, header->len, "received");
-f
+
    for (i = 0; i < dev->addr_count; i++) {
      if (memcmp(data, dev->filter_address[i], 6) == 0) to_me = 1;
      if (memcmp(&data[6], dev->filter_address[i], 6) == 0) from_me = 1;
@ -2165,7 +2304,8 @@ f
    /* AUTODIN II hash mode? */
    if ((dev->hash_filter) && (!to_me) && (data[0] & 0x01))
      to_me = _eth_hash_lookup(dev->hash, data);
-#endif /* USE_BPF */
+    break;
  }
 /* detect reception of loopback packet to our physical address */
 if (LOOPBACK_SELF_FRAME(dev->physical_addr, data)) {
@ -2179,20 +2319,15 @@ f
    dev->loopback_self_sent--;
    to_me = 0;
    }
 #ifndef USE_BPF
  else
    if (!bpf_used)
      from_me = 0;
 #endif
 #ifdef USE_READER_THREAD
  pthread_mutex_unlock (&dev->self_lock);
 #endif
  }
-#ifdef USE_BPF
+if (bpf_used ? to_me : (to_me && !from_me)) {
  if (to_me) {
 #else /* !USE_BPF */
  if (to_me && !from_me) {
 #endif
  if (header->len > ETH_MIN_JUMBO_FRAME) {
    if (header->len <= header->caplen) /* Whole Frame captured? */
      _eth_fix_ip_jumbo_offload(dev, data, header->len);
@ -2230,7 +2365,7 @@ f
    pthread_mutex_unlock (&dev->lock);
    free(moved_data);
    }
-#else
+#else /* !USE_READER_THREAD */
  /* set data in passed read packet */
  dev->read_packet->len = header->len;
  memcpy(dev->read_packet->msg, data, header->len);
@ -2281,10 +2416,13 @@ int eth_read(ETH_DEV* dev, ETH_PACK* packet, ETH_PCALLBACK routine)
 /* dispatch read request to either receive a filtered packet or timeout */
 do {
-    if (dev->pcap_mode)
+  switch (dev->eth_api) {
    case ETH_API_PCAP:
      status = pcap_dispatch((pcap_t*)dev->handle, 1, &_eth_callback, (u_char*)dev);
      break;
 #ifdef USE_TAP_NETWORK
-    else {
+    case ETH_API_TAP:
      if (1) {
        struct pcap_pkthdr header;
        int len;
        u_char buf[ETH_MAX_JUMBO_FRAME];
@ -2295,11 +2433,32 @@ int eth_read(ETH_DEV* dev, ETH_PACK* packet, ETH_PCALLBACK routine)
          status = 1;
          header.caplen = header.len = len;
          _eth_callback((u_char *)dev, &header, buf);
-      } else {
+          }
        else
          status = 0;
        }
-    }
+      break;
 #endif /* USE_TAP_NETWORK */
 #ifdef USE_VDE_NETWORK
    case ETH_API_VDE:
      if (1) {
        struct pcap_pkthdr header;
        int len;
        u_char buf[ETH_MAX_JUMBO_FRAME];
        memset(&header, 0, sizeof(header));
        len = vde_recv((VDECONN*)dev->handle, buf, sizeof(buf), 0);
        if (len > 0) {
          status = 1;
          header.caplen = header.len = len;
          _eth_callback((u_char *)dev, &header, buf);
          }
        else
          status = 0;
        }
      break;
 #endif /* USE_VDE_NETWORK */
    }
  } while ((status) && (0 == packet->len));
 #else /* USE_READER_THREAD */
@ -2467,12 +2626,11 @@ t_stat eth_filter_hash(ETH_DEV* dev, int addr_count, ETH_MAC* const addresses,
 sim_debug(dev->dbit, dev->dptr, "BPF string is: |%s|\n", buf);
 /* get netmask, which is required for compiling */
-  if (dev->pcap_mode && (pcap_lookupnet(dev->handle, &bpf_subnet, &bpf_netmask, errbuf)<0)) {
+if ((dev->eth_api == ETH_API_PCAP) && (pcap_lookupnet(dev->handle, &bpf_subnet, &bpf_netmask, errbuf)<0))
  bpf_netmask = 0;
  }
 #ifdef USE_BPF
-  if (dev->pcap_mode) {
+if (dev->eth_api == ETH_API_PCAP) {
  /* compile filter string */
  if ((status = pcap_compile(dev->handle, &bpf, buf, 1, bpf_netmask)) < 0) {
    sprintf(errbuf, "%s", pcap_geterr(dev->handle));
@ -2484,7 +2642,8 @@ t_stat eth_filter_hash(ETH_DEV* dev, int addr_count, ETH_MAC* const addresses,
    msg = "Eth: BPF string is: |%s|\r\n";
    printf (msg, buf);
    if (sim_log) fprintf (sim_log, msg, buf);
-    } else {
+    }
  else {
    /* apply compiled filter string */
    if ((status = pcap_setfilter(dev->handle, &bpf)) < 0) {
      sprintf(errbuf, "%s", pcap_geterr(dev->handle));
@ -2492,7 +2651,8 @@ t_stat eth_filter_hash(ETH_DEV* dev, int addr_count, ETH_MAC* const addresses,
      printf(msg, errbuf);
      if (sim_log) fprintf (sim_log, msg, errbuf);
      sim_debug(dev->dbit, dev->dptr, "Eth: pcap_setfilter error: %s\n", errbuf);
-      } else {
+      }
    else {
 #ifdef USE_SETNONBLOCK
      /* set file non-blocking */
      status = pcap_setnonblock (dev->handle, 1, errbuf);
@ -2567,9 +2727,8 @@ int eth_host_devices(int used, int max, ETH_LIST* list)
    sprintf( regkey, "SYSTEM\\CurrentControlSet\\Control\\Network\\"
             "{4D36E972-E325-11CE-BFC1-08002BE10318}\\%hs\\Connection", list[i].name+
             strlen( "\\Device\\NPF_" ) );
-      if((status = RegOpenKeyExA (HKEY_LOCAL_MACHINE, regkey, 0, KEY_QUERY_VALUE, &reghnd)) != ERROR_SUCCESS) {
+    if ((status = RegOpenKeyExA (HKEY_LOCAL_MACHINE, regkey, 0, KEY_QUERY_VALUE, &reghnd)) != ERROR_SUCCESS)
      continue;
      }
    reglen = sizeof(regval);
    /* look for user-defined adapter name, bail if not found */  
@ -2602,24 +2761,33 @@ int eth_host_devices(int used, int max, ETH_LIST* list)
  ++used;
  }
 #endif
 #ifdef USE_VDE_NETWORK
 if (used < max) {
  list[used].num = used;
  sprintf(list[used].name, "%s", "vde:device");
  sprintf(list[used].desc, "%s", "Integrated VDE support");
  ++used;
  }
 #endif
 return used;
 }
 int eth_devices(int max, ETH_LIST* list)
 {
 int i = 0;
 #ifndef DONT_USE_PCAP_FINDALLDEVS
 pcap_if_t* alldevs;
 pcap_if_t* dev;
  int i = 0;
 char errbuf[PCAP_ERRBUF_SIZE];
 #ifndef DONT_USE_PCAP_FINDALLDEVS
 /* retrieve the device list */
 if (pcap_findalldevs(&alldevs, errbuf) == -1) {
  char* msg = "Eth: error in pcap_findalldevs: %s\r\n";
  printf (msg, errbuf);
  if (sim_log) fprintf (sim_log, msg, errbuf);
-  } else {
+  }
 else {
  /* copy device list into the passed structure */
  for (i=0, dev=alldevs; dev; dev=dev->next) {
    if ((dev->flags & PCAP_IF_LOOPBACK) || (!strcmp("any", dev->name))) continue;
--- a/sim_ether.h
+++ b/sim_ether.h
@ -28,6 +28,7 @@
  Modification history:
  30-Oct-11  MP   Added support for vde (Virtual Distributed Ethernet) networking
  18-Apr-11  MP   Fixed race condition with self loopback packets in 
                  multithreaded environments
  09-Dec-10  MP   Added support to determine if network address conflicts exist
@ -89,13 +90,13 @@
 #if defined (USE_READER_THREAD)
 #if defined (USE_SETNONBLOCK)
 #undef USE_SETNONBLOCK
-#endif
+#endif /* USE_SETNONBLOCK */
 #undef PCAP_READ_TIMEOUT
 #define PCAP_READ_TIMEOUT 15
-#if !defined (xBSD) && !defined(_WIN32) && !defined(VMS)
+#if (!defined (xBSD) && !defined(_WIN32) && !defined(VMS)) || defined (USE_TAP_NETWORK) || defined (USE_VDE_NETWORK)
-#define MUST_DO_SELECT
+#define MUST_DO_SELECT 1
 #endif
 #endif
 #endif /* USE_READER_THREAD */
 /*
  USE_BPF is defined to let this code leverage the libpcap/OS kernel provided 
@ -175,7 +176,10 @@ struct eth_device {
  char*         name;                                   /* name of ethernet device */
  void*         handle;                                 /* handle of implementation-specific device */
  int           fd_handle;                              /* fd to kernel device (where needed) */
-  int           pcap_mode;                              /* Flag indicating if pcap API are being used to move packets */
+  int           eth_api;                                /* Designator for which API is being used to move packets */
 #define ETH_API_PCAP 0                                  /* Pcap API in use */
 #define ETH_API_TAP  1                                  /* tun/tap API in use */
 #define ETH_API_VDE  2                                  /* VDE API in use */
  ETH_PCALLBACK read_callback;                          /* read callback function */
  ETH_PCALLBACK write_callback;                         /* write callback function */
  ETH_PACK*     read_packet;                            /* read packet */
--- a/sim_tape.c
+++ b/sim_tape.c
@ -320,14 +320,16 @@ return SCPE_NOFNC;
 struct tape_context *ctx = (struct tape_context *)uptr->tape_ctx;
 pthread_attr_t attr;
-ctx->asynch_io = 1;
+ctx->asynch_io = sim_asynch_enabled;
 ctx->asynch_io_latency = latency;
 if (ctx->asynch_io) {
    pthread_mutex_init (&ctx->io_lock, NULL);
    pthread_cond_init (&ctx->io_cond, NULL);
    pthread_attr_init(&attr);
    pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
    pthread_create (&ctx->io_thread, &attr, _tape_io, (void *)uptr);
    pthread_attr_destroy(&attr);
    }
 uptr->a_check_completion = _tape_completion_dispatch;
 #endif
 return SCPE_OK;
@ -362,6 +364,7 @@ static void _sim_tape_io_flush (UNIT *uptr)
 {
 #if defined (SIM_ASYNCH_IO)
 sim_tape_clr_async (uptr);
 if (sim_asynch_enabled)
    sim_tape_set_async (uptr, 0);
 #endif
 fflush (uptr->fileref);
--- a/sim_timer.c
+++ b/sim_timer.c
@ -23,6 +23,28 @@
   used in advertising or otherwise to promote the sale, use or other dealings
   in this Software without prior written authorization from Robert M Supnik.
   21-Oct-11    MP      Fixed throttling in several ways:
                         - Sleep for the observed clock tick size while throttling
                         - Recompute the throttling wait once every 10 seconds
                           to account for varying instruction mixes during
                           different phases of a simulator execution or to 
                           accommodate the presence of other load on the host 
                           system.
                         - Each of the pre-existing throttling modes (Kcps, 
                           Mcps, and %) all compute the appropriate throttling 
                           interval dynamically.  These dynamic computations
                           assume that 100% of the host CPU is dedicated to 
                           the current simulator during this computation.
                           This assumption may not always be true and under 
                           certain conditions may never provide a way to 
                           correctly determine the appropriate throttling 
                           wait.  An additional throttling mode has been added
                           which allows the simulator operator to explicitly
                           state the desired throttling wait parameters.
                           These are specified by: 
                                  SET THROT insts/delay
                           where 'insts' is the number of instructions to 
                           execute before sleeping for 'delay' milliseconds.
   22-Apr-11    MP      Fixed Asynch I/O support to reasonably account cycles
                        when an idle wait is terminated by an external event
   05-Jan-11    MP      Added Asynch I/O support
@ -67,6 +89,7 @@ static uint32 sim_throt_ms_stop = 0;
 static uint32 sim_throt_type = 0;
 static uint32 sim_throt_val = 0;
 static uint32 sim_throt_state = 0;
 static uint32 sim_throt_sleep_time = 0;
 static int32 sim_throt_wait = 0;
 extern int32 sim_interval, sim_switches;
 extern FILE *sim_log;
@ -152,8 +175,7 @@ return sim_os_msec () - stime;
 }
 #if defined(SIM_ASYNCH_IO)
-#ifndef CLOCK_REALTIME
+#ifdef NEED_CLOCK_GETTIME
 #define CLOCK_REALTIME 1
 int clock_gettime(int clk_id, struct timespec *tp)
 {
 uint32 secs, ns, tod[2], unixbase[2] = {0xd53e8000, 0x019db1de};
@ -225,12 +247,13 @@ Sleep (msec);
 return sim_os_msec () - stime;
 }
-#if !defined(CLOCK_REALTIME) && defined (SIM_ASYNCH_IO)
+#if defined(NEED_CLOCK_GETTIME)
 #define CLOCK_REALTIME 1
 int clock_gettime(int clk_id, struct timespec *tp)
 {
 t_uint64 now, unixbase;
 if (clk_id != CLOCK_REALTIME)
    return -1;
 unixbase = 116444736;
 unixbase *= 1000000000;
 GetSystemTimeAsFileTime((FILETIME*)&now);
@ -315,8 +338,7 @@ treq.tv_nsec = (milliseconds % MILLIS_PER_SEC) * NANOS_PER_MILLI;
 return sim_os_msec () - stime;
 }
-#if !defined(CLOCK_REALTIME) && defined (SIM_ASYNCH_IO)
+#if defined(NEED_CLOCK_GETTIME)
 #define CLOCK_REALTIME 1
 int clock_gettime(int clk_id, struct timespec *tp)
 {
 struct timeval cur;
@ -377,8 +399,7 @@ if (tim > SIM_IDLE_MAX)
 return tim;
 }
 #if !defined(_POSIX_SOURCE) && defined(SIM_ASYNCH_IO)
-#ifndef CLOCK_REALTIME
+#ifdef NEED_CLOCK_GETTIME
 #define CLOCK_REALTIME 1
 typedef int clockid_t;
 int clock_gettime(clockid_t clk_id, struct timespec *tp)
 {
@ -408,6 +429,21 @@ return sim_os_msec () - stime;
 #endif
 /* diff = min - sub */
 void
 sim_timespec_diff (struct timespec *diff, struct timespec *min, struct timespec *sub)
 {
 /* move the minuend value to the difference and operate there. */
 *diff = *min;
 /* Borrow as needed for the nsec value */
 if (sub->tv_nsec > min->tv_nsec) {
    --diff->tv_sec;
    diff->tv_nsec += 1000000000;
    }
 diff->tv_nsec -= sub->tv_nsec;
 diff->tv_sec -= sub->tv_sec;
 }
 #if defined(SIM_ASYNCH_IO)
 uint32 sim_idle_ms_sleep (unsigned int msec)
 {
@ -628,8 +664,11 @@ return SCPE_OK;
 t_stat sim_show_idle (FILE *st, UNIT *uptr, int32 val, void *desc)
 {
-if (sim_idle_enab)
+if (sim_idle_enab) {
-    fprintf (st, "idle enabled, stability wait = %ds, minimum sleep resolution = %dms", sim_idle_stable, sim_idle_rate_ms);
+    fprintf (st, "idle enabled");
    if (sim_switches & SWMASK ('D'))
        fprintf (st, ", stability wait = %ds, minimum sleep resolution = %dms", sim_idle_stable, sim_idle_rate_ms);
    }
 else fputs ("idle disabled", st);
 return SCPE_OK;
 }
@ -639,7 +678,7 @@ return SCPE_OK;
 t_stat sim_set_throt (int32 arg, char *cptr)
 {
 char *tptr, c;
-t_value val;
+t_value val, val2;
 if (arg == 0) {
    if ((cptr != 0) && (*cptr != 0))
@ -653,8 +692,11 @@ else {
    val = strtotv (cptr, &tptr, 10);
    if (cptr == tptr)
        return SCPE_ARG;
    sim_throt_sleep_time = sim_idle_rate_ms;
    c = toupper (*tptr++);
-    if (*tptr != 0)
+    if (c == '/')
        val2 = strtotv (tptr, &tptr, 10);
    if ((*tptr != 0) || (val == 0))
        return SCPE_ARG;
    if (c == 'M') 
        sim_throt_type = SIM_THROT_MCYC;
@ -662,6 +704,9 @@ else {
        sim_throt_type = SIM_THROT_KCYC;
    else if ((c == '%') && (val > 0) && (val < 100))
        sim_throt_type = SIM_THROT_PCT;
    else if ((c == '/') && (val2 != 0)) {
        sim_throt_type = SIM_THROT_SPC;
        }
    else return SCPE_ARG;
    if (sim_idle_enab) {
        printf ("Idling disabled\n");
@ -670,6 +715,14 @@ else {
        sim_clr_idle (NULL, 0, NULL, NULL);
        }
    sim_throt_val = (uint32) val;
    if (sim_throt_type == SIM_THROT_SPC) {
        if (val2 >= sim_idle_rate_ms)
            sim_throt_sleep_time = (uint32) val2;
        else {
            sim_throt_sleep_time = (uint32) (val2 * sim_idle_rate_ms);
            sim_throt_val = (uint32) (val * sim_idle_rate_ms);
            }
        }
    }
 return SCPE_OK;
 }
@ -693,13 +746,17 @@ else {
        fprintf (st, "Throttle = %d%%\n", sim_throt_val);
        break;
    case SIM_THROT_SPC:
        fprintf (st, "Throttle = %d ms every %d cycles\n", sim_throt_sleep_time, sim_throt_val);
        break;
    default:
        fprintf (st, "Throttling disabled\n");
        break;
        }
    if (sim_switches & SWMASK ('D')) {
-        fprintf (st, "Wait rate = %d ms\n", sim_idle_rate_ms);
+        fprintf (st, "minimum sleep resolution = %d ms\n", sim_idle_rate_ms);
        if (sim_throt_type != 0)
            fprintf (st, "Throttle interval = %d cycles\n", sim_throt_wait);
        }
@ -712,7 +769,6 @@ void sim_throt_sched (void)
 sim_throt_state = 0;
 if (sim_throt_type)
    sim_activate (&sim_throt_unit, SIM_THROT_WINIT);
 return;
 }
 void sim_throt_cancel (void)
@ -722,7 +778,8 @@ sim_cancel (&sim_throt_unit);
 /* Throttle service
-   Throttle service has three distinct states
+   Throttle service has three distinct states used while dynamically
   determining a throttling interval:
       0    take initial measurement
       1    take final measurement, calculate wait values
@ -734,12 +791,16 @@ t_stat sim_throt_svc (UNIT *uptr)
 uint32 delta_ms;
 double a_cps, d_cps;
 if (sim_throt_type == SIM_THROT_SPC) {                  /* Non dynamic? */
    sim_throt_state = 2;                                /* force state */
    sim_throt_wait = sim_throt_val;
    }
 switch (sim_throt_state) {
    case 0:                                             /* take initial reading */
        sim_throt_ms_start = sim_os_msec ();
        sim_throt_wait = SIM_THROT_WST;
-        sim_throt_state++;                              /* next state */
+        sim_throt_state = 1;                            /* next state */
        break;                                          /* reschedule */
    case 1:                                             /* take final reading */
@ -761,24 +822,32 @@ switch (sim_throt_state) {
                d_cps = (double) sim_throt_val * 1000.0;
            else d_cps = (a_cps * ((double) sim_throt_val)) / 100.0;
            if (d_cps >= a_cps) {
-                sim_throt_state = 0;
+                sim_throt_sched ();                     /* start over */
                return SCPE_OK;
                }
            sim_throt_wait = (int32)                    /* time between waits */
                ((a_cps * d_cps * ((double) sim_idle_rate_ms)) /
                 (1000.0 * (a_cps - d_cps)));
            if (sim_throt_wait < SIM_THROT_WMIN) {      /* not long enough? */
-                sim_throt_state = 0;
+                sim_throt_sched ();                     /* start over */
                return SCPE_OK;
                }
-            sim_throt_state++;
+            sim_throt_ms_start = sim_throt_ms_stop;
            sim_throt_state = 2;
 //            fprintf (stderr, "Throttle values a_cps = %f, d_cps = %f, wait = %d\n",
 //                a_cps, d_cps, sim_throt_wait);
            }
        break;
    case 2:                                             /* throttling */
-        sim_os_ms_sleep (1);
+        sim_os_ms_sleep (sim_throt_sleep_time);
        delta_ms = sim_os_msec () - sim_throt_ms_start;
        if ((sim_throt_type != SIM_THROT_SPC) &&        /* when dynamic throttling */
            (delta_ms >= 10000)) {                      /* recompute every 10 sec */
            sim_throt_ms_start = sim_os_msec ();
            sim_throt_wait = SIM_THROT_WST;
            sim_throt_state = 1;                        /* next state */
            }
        break;
        }
--- a/sim_timer.h
+++ b/sim_timer.h
@ -31,6 +31,26 @@
 #ifndef _SIM_TIMER_H_
 #define _SIM_TIMER_H_   0
 #include <time.h>
 #if defined (__APPLE__)
 #define HAVE_STRUCT_TIMESPEC 1   /* OSX defined the structure but doesn't tell us */
 #endif
 #ifndef CLOCK_REALTIME
 #define CLOCK_REALTIME 1
 #define NEED_CLOCK_GETTIME 1
 #ifndef HAVE_STRUCT_TIMESPEC
 #define HAVE_STRUCT_TIMESPEC 1
 struct timespec {
        long tv_sec;
        long tv_nsec;
 };
 #endif /* HAVE_STRUCT_TIMESPEC */
 int clock_gettime(int clock_id, struct timespec *tp);
 #endif
 #define SIM_NTIMERS     8                               /* # timers */
 #define SIM_TMAX        500                             /* max timer makeup */
@ -46,11 +66,13 @@
 #define SIM_THROT_WMIN  100                             /* min wait */
 #define SIM_THROT_MSMIN 10                              /* min for measurement */
 #define SIM_THROT_NONE  0                               /* throttle parameters */
-#define SIM_THROT_MCYC  1
+#define SIM_THROT_MCYC  1                               /* MegaCycles Per Sec */
-#define SIM_THROT_KCYC  2
+#define SIM_THROT_KCYC  2                               /* KiloCycles Per Sec */
-#define SIM_THROT_PCT   3
+#define SIM_THROT_PCT   3                               /* Max Percent of host CPU */
 #define SIM_THROT_SPC   4                               /* Specific periodic Delay */
 t_bool sim_timer_init (void);
 void sim_timespec_diff (struct timespec *diff, struct timespec *min, struct timespec *sub);
 int32 sim_rtcn_init (int32 time, int32 tmr);
 void sim_rtcn_init_all (void);
 int32 sim_rtcn_calb (int32 ticksper, int32 tmr);