Last Updated or created 2024-06-05

Started working on my breadboard version of a 68k computer.
When it’s working, I’ll make a PCB version.
Using almost only parts I still have. (No 8mhz crystal)

The 68000 being 24 bit address and 16 bit data needs 2x 8-bit roms and 2x 8 bit ram, but i didn’t have the components yet in this picture.

While tinkering with above, my Fatter Agnus chip came in.

To make a 1mb chipmem version of your rev 5 amiga (PAL)

You need to have a newer version of the Agnus chip (I had 8371, and bought a 8372a) AND you need a 512kb trapdoor memory expansion.

An unmodded rev 5 will see 512kb Chip mem and 512 Fast mem.

Replacing the Agnus 8371 for 8372a:
I lost my PLCC puller, so I modded a paperclip into a puller 🙂

When placing the new chip, I had to tape pin 41 for PAL version.
I used Polyimide Film tape.

Next I had to cut the jumper 2 connection and solder the other pads.
(Bottom and middle disconnect and middle and top bridged)

Next was another cut on the PCB, this disables the trapdoor card detection.

Success!