- Extra queue and timer units on RQB, RQC, and RQD are now properly
initialized.
- PDP11 unit numbers are numbered:
device RQ 0-3
device RQB 4-7
device RQC 8-11
device RQD 12-15
Some devices have dedicated units that perform various independent
functions (often timing) that are independent of the primary device unit
which is ATTACHed. This services to help interpret debug information
that may be produced.
These changes facilitate more robust parameter type checking and helps
to identify unexpected coding errors.
Most simulators can now also be compiled with a C++ compiler without
warnings.
Additionally, these changes have also been configured to facilitate easier
backporting of simulator and device simulation modules to run under the
simh v3.9+ SCP framework.
The RSX-11M+ boot driver expects a slower response from the simulated
UDA50 controller. This response is only in during the MSCP initialization
sequence, so normal protocol interactions for read and write I/O are
unchanged. Updated value determined by John Forcast. Fixes#216.
Vector values contained in device information blocks are the true bus relative vector values. CPU specific biased vector values are produced by the respective vector fetching logic and vector values are limited to 9 bits with <1:0> = 0 as specified in both the Unibus and Qbus documents.
Here's a PDP11 SIMH bug as old as the simulator itself: the reset_cpu routine sets the PS to 340 (interrupts disabled). This causes some versions of Lunar Lander not to work. In fact, the initial state of the PS is not architecturally standardized:
04: cleared (from schematics)
05: cleared (from manual)
20: cleared (from schematics)
34: cleared (from schematics), set to 340 on boot?
40: cleared (from schematics)
44: cleared on init, set to 340 on boot (from schematics, manual)
45: cleared (from schematics)
60: cleared (from schematics)
70: cleared (from schematics)
T11: set to 340 (from spec)
LSI11, F11: 4 mode behavior (from memory on power recovery, cleared on GO, 340 on boot, mode 3 undefined)
J11: 4 mode behavior (from memory on power recovery, cleared on GO, 340 on boot, 340 on jump to custom PROM)
The story seems to be this. All non-VLSI PDP11s used TTL chips to implement the PS, either discrete flip-flops, or 4b registers, or both.
Starting with the first system, the 11/20, they were wired clear on the processor INIT signal (power-up or front panel START switch), so that all internal state started as 0. This worked fine, because START also reset the Unibus and cleared all interrupt enables. So even though the processor was as IPL = 0, no interrupts were possible. Then along came the LSI11...
The LSI11 implemented a line-time clock with NO INTERRUPT DISABLE. Thus, if IPL was left at 0 and a bootstrap routine from a slow device was started (e.g., a floppy drive), the clock would tick, and an interrupt would occur, before the bootstrap routine finished. Because no vectors were set up, the processor would crash. So the LSI11 started the practice, carried over to all later PDP11 VLSI chips, of setting the PS to 340 before jumping to a boot ROM.
The T11 did this in all modes of startup, because its only startup behavior was to jump to a "boot" routine. It did not have a console of any kind.
Accordingly, it appears that the cpu_reset routine needs to set the PS based on the processor model. Further, all boot routines need to set the PS to 0 or 340 based on the processor model. (It's probably safe for boot routines just to set the PS to 340, but it's not technically
accurate.)
Show IOSPACE doesn't always get the number of devices right due to device creativity.
o The distinction between UNIT and DEVICE has blurred
o MUX devices merge several physical devices into one device/unit
o Dynamic device sizing has made things more volatile.
This edit solves the problem for SHOW IOSPACE by adding an (optional) word to the DIBs.
The word contains the amount of IO space consumed by each instance of the physical device that's being emulated.
E.G., if it's a DZ11, the device is the DZ11 module, or 8 lines, even though the MUX device may support 32.
This enables SHOW IOSPACE to determine the number of physical devices being emulated, which is what folks need when configuring software. The word may have other uses - in a generic dynamic device sizing routine - which is why the amount of IOSPACE per device was chosen rather than the 'number of physical devices.'
The edit should not make any existing device regress. If the new word (ulnt) is zero (not initialized), SHOW IOSPACE will default to the number of units in the device, or if there's no device (CPUs), 1 as before. If it is present, the number of devices is the calculated as total allocation/allocation-per-device.
The edit updates all the devices that seem to require this treatment, and all the processors that define the UNIBUS/QBUS DIBs.
