3 Apr
2015
3 Apr
'15
8:57 p.m.
On Fri, Apr 3, 2015 at 2:30 AM, F.Ulivi <fulivi at tiscali.it> wrote:
I'm going to use the ASM48 assembler to write a
firmware from scratch
for the PIO (parallel I/O) microcontroller on the IOC board. It's a
8041A (ROM masked version) and it's labelled A72 on the schematics.
By looking at the picture you took of an IOC board it's clearly a masked
ROM (no UV window). Because of this I think it would be very hard to
find the ROM image. AFAIK dumping it would require a microphotograph of
the die and a lot of patience to recover the ROM bits....
I'm 99% certain that the 8041 and 8041A masked ROMs can be read with
essentially the same verification mode as the 8048 and 8048A,
respectively.
If I recall correctly, for the 8048, ROM verification mode works just
like verification of the EPROM of an 8748, but with 12V on the PROG
pin rather than 25V. The A-suffix parts have different
programming/verification requirements than the non-A parts, so be
careful.