#ea8332

[commodorez]

Old mask ROM vs. new EPROM

[commodorez]

Two diodes later, and I was able to dump an EA8332 ROM! Now for the real test: burning a 2532 EPROM

[commodorez]

Got in a few things in the mail today: 28-pin ZIF sockets, 4 of them to be exact.  And a single 2532 EPROM.  The 2532 is pin-compatible with the 8332 mask ROM, which will simply my H19 programming process significantly. 

Plus, all of other machines seem to use 2532′s, but my EPROM programmer doesn’t have a setting for that specific wiring configuration.  So I made an adapter board!  This is going to simplify my programming process quite a bit.  The adapter board is made out of a little protoboard, some short wire wrap grade wires (why didn’t I buy these sooner?), and a long machine pin 28 pin socket with gold plating. 

The 2532 is running it’s cycle in the UV eraser as we speak.

[commodorez]

I’ve manged to remove the hard-soldered traces that determine chip select, address lines, and voltages for the H19 ROMs. 

There are two sockets in the design, but most implementations are new enough to use a single EA8332 Mask ROM, instead of two EA8316′s.  I had to cut a few traces, due to the late era of this board’s manufacture.  However, now it matches the style of the oldest variations, with the flexibility that was intended.

I also removed 4 of the 5 on-board linear voltage regulators and hard-wired the board to accept +5V, +12V, and -12V directly from a power supply.  Now I just need to perform some tests with a bench power supply to confirm that I’ve done it correctly.  After that, I need to swap in some custom ROMs and hope it all works out.