Notices by paulrickards (paulrickards@mastodon.social), page 4

Some parts from eBay (China and India) have arrival estimates as late as Oct 26 😬 Maybe it’ll come sooner 🤞

I created this adapter board for a 27C512 EPROM to work in place of a MMI 6309 PROM. I'll think about this some more and maybe order some boards to try it. $5.50 for three at OSH Park, not bad.

#RetroComputing

I've been pondering another strategy for the Lisa PROMs needed for the #AppleLisaClone project. Could an (E)EPROM be used instead? With the appropriate adapter and fast enough response time, might it work? I think vintage arcade folks do this now. I've successfully used EPROMs before in a #C64 for the PLA.

I have a stash of W27C512 that are 45ns which I think is fast enough to replace a MMI 6309. There would be a lot of wasted space but who cares?

Thoughts?

#RetroComputing

68000 processor checking in for Lisa duty. The size! Are there chips in a DIP package larger than this?

#RetroComputing

I noticed that there was an open source command line tool made for the MiniPRO TL866xx series of USB EPROM burners. It includes the ability to read bipolar PROMs (specifically the 82S135), something the provided GUI software can’t do!

First I concatenated the PROM code (256 bytes) 256 times to reach the 65536 bytes of the EEPROM (a Winbond W27C512-45Z).

#AppleLisaClone #RetroComputing

I ordered these 27C512 EPROM to 6309 PROM adapter boards last night so we’ll know if they work eventually.

#AppleLisaClone #RetroComputing

It begins.

#AppleLisaClone #RetroComputing

Some folks asked for the link to the MiniPRO command line tools I used: https://gitlab.com/DavidGriffith/minipro

It can read PROMs but not write them. Although I’m not sure what’s stopping it, other than knowing the programming procedures for each PROM and writing the code for it..

Then burned it to the W27C512 EEPROM.

Then I prototyped the board with jumpers to a breadboard and tried it to see if we can at least fool the MiniPRO into thinking the 27C512 is a 82S135 (6309 read equiv).

Happy to report that it works so I’ve at least swizzled the pins in the right order! Won’t know for sure until it’s in circuit but it’s promising.

#AppleLisaClone #RetroComputing

Next up: the I/O board.: sockets done!

#AppleLisaClone #RetroComputing

#AppleLisaClone motherboard done! ✅ I’ll add expansion slots and resolve the missing, hard to source video connector later.

#RetroComputing

Created the power cable harness (and cable laced it!) between the power supply and the motherboard.

#AppleLisaClone #RetroComputing

Started building the ArduinoFile emulator and the COPS emulator.

#AppleLisaClone #RetroComputing #

I/O board passives mostly installed.

#AppleLisaClone #RetroComputing

More work on the #AppleLisaClone I/O board, installing the chips, diodes, and transistors. The last remaining parts are inbound.

#RetroComputing

#ArcaneByte #mac2lisa keyboard adapter. This allows me to use a Mac 128/512 or Plus keyboard with the #AppleLisaClone There’s also a version that has ADB but I decided to go with a Plus keyboard because it looks the part.

#RetroComputing

Plugged in the 6309 “VSROM” emulator into the (original) CPU board of the #AppleLisaClone along with the two missing ROMs and the 68000. That completes this board.

Hopefully some more parts for the IO board will be arriving soon.

#RetroComputing

Since I’m impatient waiting for my boards to be delivered, I created a 27C512 EPROM to 6309 footprint adapter (more than just DuPont wires this time) for the #AppleLisaClone CPU card. It too reads fine in the EPROM burner, masquerading as a 6309 properly.

#RetroComputing

I'm falling down a rabbit hole learning how to use WinCUPL to program a GAL22V10 to replace the PROMs in the #AppleLisaClone. I think I have a PLD file created with the PROM contents but keep running out of product terms for one output. I guess this would require hand optimization to fit within the limits of the GAL.

Soldering complete! All sockets and passives installed on the Lisa parallel card.

#AppleLisaClone #RetroComputing