...
I implemented these by adding a parameter “extended_inst” to the cpu20 device. When set the code now emulates these instructions.
Testing the EIS instructions: FKAC..
The 11/34 (KD11-B) implements these instructions, and there is a specific test for them, details here. The FKAC test tests these EIS instructions, so, let’s run it. Sadly enough it halts “CPU Halt by instruction” at 000014. I enabled Trace level on the Unibone, and the log (dbg s) shows:
...
But there is an instruction there with the same opcode, at 000620: MTPS. Which is according to the docs a LSI11 only instruction which moves a word to the PSW. It has an accompanying read called MFPS. This is odd because the 11/34 is not a LSI11 CPU, but the test’s documentation says:
...
Implementing MTPS and MFPS
So, apparently the 11/34 implemented that MTPS instruction. Sigh. This was confirmed here:
“The Micro/J-11 supported all of the possible PDP-11 instructions, except for those unique to the PDP-11/60, and the PDP-11/34 (MTPS and MFPS).“
I implemented the mtps (1064xx) and mfps (1067xx) instructions by adding yet another cpu20 parameter:
| Code Block |
|---|
parameter_bool_c allow_mxps = parameter_bool_c(this, "allow_mxps", "mxps",/*readonly*/
false, "Allow mtps and mfps instructions (1=11/34, LSI11, 0=standard 11/20 behavior)"); |
Next run
The next run came a lot further but still died with a trap 010, illegal instruction. The log showed:
| Code Block |
|---|
[11:42:20.938773 Dbg cpu 03410@ka11.c:0412] EXEC [000726] MOV
[11:42:20.938777 Dbg cpu 03410@ka11.c:0161] DATI [000730] => 000001
[11:42:20.938780 Dbg cpu 03410@ka11.c:0161] DATI [000732] => 000440
[11:42:20.938784 Dbg cpu 03410@ka11.c:0161] DATI [000440] => 000000
[11:42:20.938787 Dbg cpu 03410@ka11.c:0174] DATO [000440] <= 000001
[11:42:20.938793 Dbg cpu 03410@ka11.c:0161] DATI [000734] => 005037
[11:42:20.938797 Dbg cpu 03410@ka11.c:0639] EXEC [000734] CLR
[11:42:20.938800 Dbg cpu 03410@ka11.c:0161] DATI [000736] => 000442
[11:42:20.938803 Dbg cpu 03410@ka11.c:0161] DATI [000442] => 000014
[11:42:20.938807 Dbg cpu 03410@ka11.c:0174] DATO [000442] <= 000000
[11:42:20.938814 Dbg cpu 03410@ka11.c:0161] DATI [000740] => 010701
[11:42:20.938817 Dbg cpu 03410@ka11.c:0412] EXEC [000740] MOV
[11:42:20.938824 Dbg cpu 03410@ka11.c:0161] DATI [000742] => 013700
[11:42:20.938827 Dbg cpu 03410@ka11.c:0412] EXEC [000742] MOV
[11:42:20.938831 Dbg cpu 03410@ka11.c:0161] DATI [000744] => 000434
[11:42:20.938834 Dbg cpu 03410@ka11.c:0161] DATI [000434] => 000001
[11:42:20.938840 Dbg cpu 03410@ka11.c:0161] DATI [000746] => 032737
[11:42:20.938843 Dbg cpu 03410@ka11.c:0423] EXEC [000746] BIT
[11:42:20.938847 Dbg cpu 03410@ka11.c:0161] DATI [000750] => 000001
[11:42:20.938850 Dbg cpu 03410@ka11.c:0161] DATI [000752] => 000406
[11:42:20.938854 Dbg cpu 03410@ka11.c:0161] DATI [000406] => 000000
[11:42:20.938860 Dbg cpu 03410@ka11.c:0161] DATI [000754] => 001004
[11:42:20.938864 Dbg cpu 03410@ka11.c:0738] EXEC [000754] BNE
[11:42:20.938870 Dbg cpu 03410@ka11.c:0161] DATI [000756] => 013701
[11:42:20.938873 Dbg cpu 03410@ka11.c:0412] EXEC [000756] MOV
[11:42:20.938877 Dbg cpu 03410@ka11.c:0161] DATI [000760] => 000436
[11:42:20.938880 Dbg cpu 03410@ka11.c:0161] DATI [000436] => 000000
[11:42:20.938886 Dbg cpu 03410@ka11.c:0161] DATI [000762] => 072001
[11:42:20.938890 Dbg cpu 03410@ka11.c:0498] EXEC [000762] ASH
[11:42:20.938897 Dbg cpu 03410@ka11.c:0161] DATI [000764] => 000402
[11:42:20.938900 Dbg cpu 03410@ka11.c:0737] EXEC [000764] BR
[11:42:20.938907 Dbg cpu 03410@ka11.c:0161] DATI [000772] => 106737
[11:42:20.938911 Dbg cpu 03410@ka11.c:0715] EXEC [000772] MFPS
[11:42:20.938914 Dbg cpu 03410@ka11.c:0174] DATOB [000772] <= 000000
[11:42:20.938920 Dbg cpu 03410@ka11.c:0161] DATI [000774] => 000432
[11:42:20.938924 Dbg cpu 03410@ka11.c:0737] EXEC [000774] BR
[11:42:20.938930 Dbg cpu 03410@ka11.c:0161] DATI [001062] => 177354
[11:42:20.938933 Dbg cpu 03410@ka11.c:0815] TRAP 10 |
Debugging using Unibone and FKAC
Speed up emulation
By default the emulation will fully control the Unibus. This means that when it runs all data is sent to it. This is necessary when testing real hardware, of course, but for my use case, testing the emulation, I do not need the Unibus to be controlled. And disabling that greatly speeds up the emulation!
Set the parameter “pmi” to 1 to disable Unibus control.
Use Unibone breakpoints
Invaluable is the “bp” parameter in the Unibone which can be used to set a single breakpoint. As the fiche I had of FKAC was a lot different from the actual code I converted the BIC file to a binary and then used pdp11dasm to disassemble that binary. With that I could at least match pieces of actual code with the fiche.
In my version of FKAC the $HLT routing which gets called at error is at location 16440oct, and this routine’s return statement is at 16622oct, so I added a breakpoint at the last address causing the test to stop as soon as an error has been found- and has been printed.