Improper implementation of the OVT and OTO instructions. OV is always zero or one, so the Boolean AND in the original if statement would always fail. Also, these instructions are supposed to skip if overflow is not set, the opposite of the way it was coded.
1. In sim_instr, if an Unauthorized Memory Access trap occurs, the code was enforcing the 940 Reference Manual's admonition that:
"The instruction in the trap location must be a MARK PLACE AND BRANCH (BRM) instruction."
Normally there is a BRM TRAPM in location 041, but when exploring a memory trap, the TSS monitor code at CEX (SMEM) temporarily puts a BRU CEX2+1 in location 041.
Clearly the hardware allows BRU in the trap transfer vector, because the system uses that feature. Change simulator to allow BRM or BRU in Unauthorized Memory Access Trap vector word in location 041.
2. Page 17 of the 940 reference manual specifies special actions when the target address of a BRU, BRX, BRM or BRR instruction cannot be accessed because it's not in the memory map. The simulator was not doing this, causing TRAPM to operate with the address of the BR? instruction instead of its target address. The result was to allocate a page of zeros, which then trapped when the branch completed and transferred to a HLT instruction.
By modifying the code in sds_cpu.c to provide the correct trap address, monitor code TRAPM does not allocate a page, and instead allows any user-defined trap to fire off. This fixes the problem with DDT, which relies on this trap to then map in the DDT SBREK page to 34000 and then complete the transfer to it for command processing.
VIDEO:
- Make mouse motion activity consistent with SDL relative direction. Add error output when mouse events are discarded due to queue full.
If a client application delivers motion information in a different relative sense, then that application needs to make the adjustments from the SDL standard direction.
- Added SHOW dev VIDEO capability to describe the underlying SDL video capabilities of the current SDL library and host execution environment.
- Force software based rendering under SDL2. Enhanced debug info.
- Added host OS cursor integration support.
- Reorganize libSDL vs libSDL2 version implementation to leverage common logic without replication.
QVSS:
- Coalesced adjacent screen row updates to minimize vid_draw operations
- Report all relative mouse motion in the mouse position register AND mouse motion data.
- Added debugging information for cursor and scan line map updates
- Add option "SET QVSS CAPTURED" to force capture input mode.
While debugging DDT subsystem of 940 time-sharing system, discovered NOP opcode used with indirection, non-zero operand address and tag field. I_V_OPO (opcode only) was redundant with I_V_NPN (no operand) opcode classes. Convert I_V_OPO to new "operand optional" class and use it for NOP, and add code to detect presence or absence of operand or tag for this class for machine code display and entry.
The existing conversion tables were for the 930 and earlier models of SDS computers. The SDS 940 altered these tables. This change selects the appropriate table based upon the current CPU mode -- whether operating as a 930 or a 940. See Appendix A of both the 930 and 940 reference manuals for detailed character conversion information. Correct 930 ASCII to internal table for ASCII input value 0140.
Commit a9ac7c153 properly avoided writing past the end of cache_line,
but in doing so introduced an error as to the first memory address that
should be written. This fix avoids writing past the cache_line by simply
reading the previous memory location.
Fixes the CP/M 68K simulation example and issue #181
When reading from paper tape on the W channel and writing the drum on the E channel, intermittent errors and premature end-of-record were observed. The TST_XFR macro was failing to properly quality that a data character was available for a particular device and channel. Thus, a data ready condition for the drum would cause a bad transfer for another active device on a different channel.
John Kichury revived Startrek II running under DCC Basic which originally ran on the Digital Computer Controls (DCC) D-116 DG Nova clone
This program (or the Basic interpreter) requires console input with even parity.
SET TTI EVEN
will now enable that.
