Bits ‘n Bobs

Wherein I potter for 2 weeks.

Lots of little projects this time. I kept working on the BBC Micro. I made up one of my Microbee ROM switchers and installed it. I now have 16 different ROMs to choose from.

I also made a “Atari to BBC” joystick adapter for all those games where I only wanted digital input. Turns out to be most of them.

I based it off the circuit found here. I just assembled it all on some experimenters board. It works well! I used parts I had lying around the house for the most part. Only had to buy transistors.

I also built up a second GBS Control unit. This one is in a slightly nicer case, with things like mounting holes on the back for attaching it to a surface, and it’s got SCART in.

I made a short CGA cable from bits I had lying around the house. The ends are from console adapters, with one pin moved. The cable between the connectors is some straight through 8 core wire that came from an old video conferencing unit. I’ve shielded it by stripping the rubber sheath on some coax, expanding the copper shield inside, sliding it over the inner 8 core, tightening it again and then heatshrinking it in place. I then crimped on RJ45 connectors to finish the job. Small, versatile.

A local collector was chasing a custom cable to go from a Commodore PC1 to a matching 75-bm13 monitor. Now, I had never heard of either, but it’s a monochrome signal, so I was able to build it up from a picture given to me and some common pinouts on the internet.

I’m 98% sure it’s right.

6 pin DIN to 9 pin D-Sub.

I’d found an old quadrature mouse in a scrapheap ages ago, Amiga / Atari ST, but it never worked. The cables seemed fine, and the mouse buttons were good so I took a punt that the problem was that the IR-LEDs in it had burned out, a common enough problem in vintage optics of this era.

I hit up the local hardware shop and purchased some 3mm IR-LEDs and carefully bent them into shape and, lo and behold, it worked!

I also tested an Apple monitor I’d had lying around for ages. It’s a an Apple ColorMonitor IIc, and I couldn’t get colour out of it. Turns out it only works with the Apple IIc, and thanks to Greg (Hi Greg!) loaning me an Apple IIc for a day, I was able to confirm it works fine. I’ll be gifting that one to Greg as a “Thank you!” for all his support over the years :-)

Choplfter looks great in NTSC colour.


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2 responses to “Bits ‘n Bobs”

  1. benc Avatar
    benc

    That is a rare screen! You’ll find that it does sorta work on pal iie with the motherboard colour switch DISABLED, however the palette will be off. You need the special A661-91097 card (plugs in aux. slot) for proper colours. Your ColorMonitor IIc is also directly compatible with platinum IIe (International NTSC mobo) & apple II europlus !!

    1. Cheshy Chesh Avatar
      Cheshy Chesh

      Thanks for the info! I’ve earmarked this screen for the original owner of the IIc as he’s been super generous to me in the past :-)

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