PCjs Machines
Home of the original IBM PC emulator for browsers.
DEC PDP-11 M9312 ROMs
As this PDP-11 website explains:
The M9312 Bootstrap/terminator module contains a complete set of UNIBUS termination resistors and 512 words of ROM that can be used for diagnostic routines, the console emulation routine and bootstrap programs. The module has 12 jumpers, W1 thu W12, and five sockets to put ROMs in. One socket is used for a diagnostic ROM for the PDP-11/60 or PDP-11/70, or for a ROM that contains the console emulation routine and diagnostics for all other PDP-11s. The other four sockets accept ROMs that contain bootstrap programs.
PDP-11 M9312 ROMs
An assortment of M9312 ROM images, source listings, etc, are available from Don North’s website, some of which we have reproduced here.
Initially, all we had was this 256-word ROM obtained from Paul Nankervis’ website. Cross-referencing that ROM with Don North’s M9312 PROM Files revealed that it came from DEC P/N 23-616F1, “11/60,70 Diagnostic/Console”, albeit with a few modifications:
165322 022716 165320 L26: cmp #N2,(sp) ; 165320 changed to 000320
...
165332 012716 165342 L27: mov #N3,(sp) ; 165342 changed to 000342
...
165344 012746 165354 mov #N4,-(sp) ; 165354 changed to 000354
...
165354 000137 165362 N4: jmp @#N5 ; 165362 changed to 000362
165360 000000 halt ; 000000 changed to 000200
...
165372 012737 165400 000004 mov #N6,@#4 ; 165400 changed to 000400
...
165406 012737 165714 000114 mov #N12,@#114 ; 165714 changed to 000714
The unmodified 23-616F1 ROM is loaded at address 165000 (0xEA00) in this PDP-11/70, using the following configuration:
<rom id="m9312" addr="0xEA00" size="0x200" file="/machines/dec/pdp11/rom/M9312/23-616F1.json5"/>