Hi all,
I’m currently in the process of restoring a Macintosh 128K logic board. After troubleshooting, I’m confident that BMU0 is defective. When I swap it with the BMU0 from another known-good 128K board, the board works correctly.
I was able to disassemble the original PAL16R4 JED using jed2eqn and extract the logic equations. I then tried to recompile these equations into new GAL code using CUPL (Device Mnemonic = G16V8MS), but unfortunately without a working result so far.
I do have GAL files for BMU2 (same physical location on a Macintosh Plus logic board), but these appear to be different from the 128K BMU0 implementation and don’t seem to be a drop-in replacement.
I’ve attached the original PAL JED file and the equation disassembler file (EQN) to this post.
At this point I’m clearly hitting the limits of my knowledge. Is there anyone here who’s more experienced with this and willing to help convert the PAL JED/EQN into a working GAL implementation?
Thanks in advance!
Daan
I’m currently in the process of restoring a Macintosh 128K logic board. After troubleshooting, I’m confident that BMU0 is defective. When I swap it with the BMU0 from another known-good 128K board, the board works correctly.
I was able to disassemble the original PAL16R4 JED using jed2eqn and extract the logic equations. I then tried to recompile these equations into new GAL code using CUPL (Device Mnemonic = G16V8MS), but unfortunately without a working result so far.
I do have GAL files for BMU2 (same physical location on a Macintosh Plus logic board), but these appear to be different from the 128K BMU0 implementation and don’t seem to be a drop-in replacement.
I’ve attached the original PAL JED file and the equation disassembler file (EQN) to this post.
At this point I’m clearly hitting the limits of my knowledge. Is there anyone here who’s more experienced with this and willing to help convert the PAL JED/EQN into a working GAL implementation?
Thanks in advance!
Daan
Last edited:
