the prom can do its own disassembly... at least on a 4k[456]00 it does.. 
e/instr 
then at least it'll diassemble it the way dec thinks it should, instead
of objdump... 
isildur

On Sat, 20 Jul 2002, Michael L. Hitch wrote:

> On Sat, 20 Jul 2002, Hugh Graham wrote:
> 
> > Saying all that makes finding DEC's programmer sound a whole lot safer.
> > Maybe one of the DECUS derivatives can scare up the necessary resources
> > if asked nicely.
> 
>   I have asked our DEC/Compaq/HP service person if he could find out
> anything through his channels.
> 
> > Hmm, since you have more information on how this chip may work, maybe
> > you can try some new combinations of the dz misprobe. When I had Chuck
> > Cranor boot my attempts at setting things right, I never had the 0x40
> > write setup in there. Perhaps this part can restore some bits without
> > requiring a full erase first after all.
> 
>   Unfortunately, the AMD chip doesn't work that way.  You have to erase
> the chip to all ones, and then clear the bits to program it.  Once a bit
> is cleared, it can only be set by erasing the entire memory.
> 
> > If not, tracking down the firmware's checksum routine may be useful,
> > in case it has a special case for an all-zeros checksum, or can be
> > zapped to always return success.
> 
>   I've tried a simple 32 bit sum, and didn't get any useful result.
> Somewhere in all the code in those images should be the test it uses to
> verify the PROM.  I've disassembled it with objdump and scanned it very
> briefly, but didn't spot anything.  The objdump output is 145,000 lines,
> which is a lot to grovel through, and objdump probably messes up some of
> the disassembly.
> 
> --
> Michael L. Hitch			mhitch@montana.edu
> Computer Consultant
> Information Technology Center
> Montana State University	Bozeman, MT	USA
> 
>