It’s been a couple of weeks since I’ve streamed anything – partly because I’m mulling over the best way forward. Live streaming is great, but it’s hard to concentrate on the task at hand when there’s an audience right there to also engage with – my hat is off to those who can concentrate on both at once! That, and sometimes I’ll hit a road-block and need to research things for a bit (or even wait a week for something to arrive), and that doesn’t make for very engaging content :-)...

So the current state of play is that IC42 (which was a VC2069) has been replaced with a VC2023 borrowed from a model B. They’re pin compatible (and I believe functionally compatible). I now have: pin 8 – 16Mhz in pin 7 – 8MHz out pin 6 – 4MHz out pin 5 – 2MHz out pin 4 – 1MHz out BUT, the 2MHz out, while it makes it to IC34 pin 2, doesn’t make it to IC28 pin 3, which results in no 1MHZE signal being generated – and that’s used by the VIA’s, they keyboard, and in various other places....

I’ve been testing with it powered from the bench PSU today (albeit without the -5V, but IIRC that’s only required for audio/serial/cassette). As far as progress, I removed IC42 (destructively – cutting pins) and socketed a spare video ULA – now I’m getting the output clock signals that I’d expect to see, and the CPU is receiving a 2MHz clock. Initially RST was stuck low on pin 40 of the CPU, yet was going high everywhere else (tube socket, cartridge slots, etc)....

I recently acquired a “may not be working, for parts” BBC Master 128. So I’m not entirely surprised it doesn’t work. Was pretty filthy, and for the most part still is. Battery pack was 3 x Duracell’s that had sweated fairly badly, but not corroded in the normal way they do. That’s been removed (and not replaced yet). Part of the top of the PSU was rusty, and the top of the video modulator is rusty....

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

A couple of nights back my streaming PC got angry with me. The first night it bluescreened once, but it rebooted and the show went on. The second night, I think Obs crashed once and it bluescreened twice. Initial thoughts were maybe it was a driver or something that I’d installed recently, but that seems less likely now. This morning I created a Memtest86 USB stick and booted into it....

This Apple ][ clone arrived in the mail today. Mightly yellowed, but other than the ‘K’ key, the machine seems to work fine. The motherboard is branded “Vectorio”, so it’ll be interesting to learn a bit more about this one. Live streams on Twitch

After the last BBC stream I pondered that maybe the suspect disc drive’s heads were just dirty, so we clean those. Then investigate a couple of Master Compact systems, and end up opening the Amiga again to work out which Kickstart ROM it had (1.3) and realised it had a mono video output! Streaming PC bluescreened towards the end, but we picked up where we left off. 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....