HP9816 PAL16L8
Paul Berger
phb.hfx at gmail.com
Mon Jun 10 18:23:15 CDT 2019
On 2019-06-08 7:14 a.m., Piero Andreini via cctalk wrote:
> desperately looking for jedec file of PAL 16L8 position U69 part # 1820-2991
I pulled the CPU board out of my HP9816 and was happy to see that the
component in question is in a socket however there is a problem. The
component in mine is a HAL16L8 note the "H" I found a datasheet and
apparently in the early days of PALs at MMI you could do your
development using PALs and then send the equations to MMI and they would
produce a mask programmed semi custom chip with the same logic. The
problem with this is it does not have a program ROM like a traditional
PAL so you cannot extract a valid JEDEC from it, I confirmed this by
dumping it as a PAL16L8 and then decompiling the JED file to extract the
equations and they are junk, even just browsing the RAW JED looked suspect.
We can hope that it is all combinational logic and I can run trough all
combinations of inputs and capture the output and we can develop
equations that way as long as they did not do anything like use feedback
to create registers as one person suggested could be done.
Paul.
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