HP9816 PAL16L8

[Paul Berger]

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.