|Re: Anyone w/a dead 15C that can decap/peel chips w/ ROMs??|
Message #13 Posted by Diego Diaz on 28 Aug 2003, 2:16 p.m.,
in response to message #12 by Randy Sloyer
Nowadays I'm involved in HP-41 ROM Packs cloning, so I'm dealing on a daily basis with Clk1, Clk2, ISA, SYNC... lines.
Yes, the HP available info about 1LF5-0301 (11C, 12C) and 1LF5-0002 (41C Fullnut) clearly says that they both share the same funcionallity and pin-out, only differences are regarding Power supply voltage management.
So the task can be achieved, provided:
a) 15C's (at early versions) still "wear" the same chip or,
b) at least another functional compatible one AND Rom's were not masked inside the processor waffer if the former is true.
Further more, if a separate ROM chip of said processor is available, reading the internal code is as simple as provide it with the required lines: Clocks 1 & 2, SYNC, ISA, PWO, V+ and GND. That can be done with a PC parallel port and a +5v DC power supply. Of course it'd be better if done at ASSEMBLY language level. Remember MOV DX,AX?? :-)
Another way to work it out migth be placing the said ROM chip into a 41C module, and loading it with DAVID assembler. This will also allow the M-code mnemonics dumping to printer. Wouldn't be nice?? ;-)
Contact me if you're interested in the info regarding this CPU.
Cheers from the Canary Islands.