Z80

This time I’m turning up the RAM Floppy card for the Z80 system, which turned out to be a bit more difficult than I expected. The primary gotcha was that I was using the RAF113.COM test utility to test the card and it kept throwing errors. Working through the tests with the oscilloscope it soon became clear that the card wasn’t being selected when the CPU was performing IO reads & writes, despite the source code for the utility confirming the card was addressed correctly (port A0). …and it was physically jumpered correctly, to the address in the source code. ...

Most of the IC’s are now in their sockets (on the CPU card at least). Getting close to being able to fire it up – just need the DS1210, and the PLCC adapter so I can do the initial programming of the flash memory. Live streams on Twitch ...

More Z80 board build… Live streams on Twitch

Recently I started putting together a Z80 based system from the Retrobrew Computers web site. The build is fairly well advanced, but I’m still waiting on some parts to finish it off. The Z80 Backplane is mostly done – I went with the 8-slot backplane because 3 was too small, 4 was borderline, and 12 was too big. I figured with an 8-slot board I could start by populating 5 connectors and add the others if I need to. ...

A look at my “main” BBC model B and the upgrades that I’ve done to it, re-assembling the other model B, checking out the double floppy drive unit, and an update on what’s been happening with the Z80 build. Live streams on Twitch

More bits arrived so the Z80 boards are starting to fill up. Gave the BBC keys a bit of a clean, and with the soldering iron fixed, took the A501 apart to see what was going on inside, and a quick run down of things to come. ...

Quick lunch time stream looking at the latest PCB’s that arrived. Z80 Backplane ECB Disk controller EBC CPU card Live streams at Twitch

Trying to get the backplane connectors into the backplane board (they’re wire wrap connectors I think, so the pins seem slightly larger)… Seeing what IC sockets I have, checking some 74 series logic chips in the Minipro, first look at the “suspect” A501 from the Amiga, and salvaging a few bits from an old PSU. ...