During 1 of 3 visits to Apex Surplus at Supercon, I found this tube of six Signetics SC80C31A chips from 1987. The tube was in the back yard, but in good shape - so who knows if they work or not.

To test them, I found an old board - an MCM51 Rev. A board from my alma mater, McMaster University. Designed by Ken Frost in the ECE department in 1994, this was my first MCS-51 board in undergrad in 2004.

I found schematics and docs, and dumped the ROM and GAL - all posted at https://github.com/rglenn/MCM51A

There is no earthly reason to upgrade an iPod Mini to 64 GB of storage.

And yet.

I got a new KVM switch, which doesn't support EDID emulation and switches the HDMI hotplug detect pin. Which means that if you switch to a different input, it disconnects the monitor. I didn't want this behaviour.

Enter the EDID emulator, with 2 HDMI ports. It uses an EEPROM chip and some wiring to make the computer think the monitor is always connected. The EEPROM contains the EDID data, which specifies the supported resolutions among other things. Mine actually has 2 EEPROMs - 1 for each port

I picked up one of the eBay Nabu computers, and have had it sitting on a desk here for a week or so. Finally breadboarded up a USB interface for it (CH340 USB UART + 2 RS485 transceivers to make a bidirectional RS422 interface) and got the Internet Adapter working. It boots!

Now to figure out what to do next.

#nabu