ZX81 repair

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  • Опубліковано 24 гру 2024

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  • @ExplainingComputers
    @ExplainingComputers 2 роки тому +9

    Interesting video. Always good to see a ZX81 brought back to life. It was my first computer on which I learnt to program in BASIC, then Z80 machine code. :)

    • @ezContents
      @ezContents  2 роки тому +2

      Thank you, Chris! It was a pleasure to work on it and fix it.

  • @akrimpen2
    @akrimpen2 2 роки тому +1

    For some reason I find it very pleasant to watch/listen to your video's while working. Keep'm coming!

    • @ezContents
      @ezContents  2 роки тому +2

      Thanks Arjan! I am very glad to hear that. 😊

  • @SqueekyBums
    @SqueekyBums Рік тому +1

    Iconic machine. I still have mine, and the ZX80 which introduced me to my first home computer. 👍

    • @ezContents
      @ezContents  Рік тому +1

      Indeed. I wish it was my first machine. My first baby steps were on ZX spectrum.

  • @MoreFunMakingIt
    @MoreFunMakingIt 2 роки тому +1

    Superb! I love that you just build your own testers.
    I have used a composite mod with backporch on one of my ZX81's. I will link it on twitter for you.
    Looking forward to more videos :D

    • @ezContents
      @ezContents  2 роки тому +1

      Thanks Lee! I had to keep myself busy while awaiting the ULA replacement.🙂

    • @leesmithsworkshop
      @leesmithsworkshop 2 роки тому +1

      @@ezContents I was just talking to other lee about building a Z80 tester for a spectrum 48k I have and then he told me about your new video.

    • @ezContents
      @ezContents  2 роки тому +1

      @@leesmithsworkshop Cool! Check the link in the description for details.

  • @JoeldaSilvaVicenteFilho
    @JoeldaSilvaVicenteFilho 2 роки тому +1

    9:05 I immediately recognized the clock module hahaha Great video o/

    • @ezContents
      @ezContents  2 роки тому +2

      Thank you! Yes, if you watched Ben Eater's series it is pretty recognizable. 😀

  • @RudysRetroIntel
    @RudysRetroIntel 2 роки тому

    Nicely done. Thanks for sharing

  • @Xoferif
    @Xoferif 2 роки тому

    That was a really good video! I've subscribed.
    I love the mini CRT TV, by the way. It really looks the part when used with a ZX81. 😄

  • @mslyczba
    @mslyczba 2 роки тому

    Amazing video 👍🏼

  • @oldblokeh
    @oldblokeh Рік тому

    Just a comment about the UK mains plug fuse. It's not there because we have 30A ring circuits - each circuit has a breaker - but to protect the device mains cable in case of a short inside the powered device. Many device cables, including in the EU, will melt and/or catch fire, or at least get very hot at currents allowed by the circuit breaker. The fuse should be rated appropriately for the device in question, regardless of the current rating of the supply circuit to which it is connected.

    • @ezContents
      @ezContents  Рік тому +1

      Thank you for clearing that up.

  • @tenminutetokyo2643
    @tenminutetokyo2643 Рік тому

    Jam in new ceramic caps too. 104's

  • @maximjacquet8434
    @maximjacquet8434 Рік тому

    you can test the sram with your eeprom programmer 😀

    • @ezContents
      @ezContents  Рік тому

      Thanks. I was making it too complicated, with the Pico and 3.3V to 5V conversions. Although I think that the problem might have been with the in/out pins, which had 2 functions.

  • @kevincozens6837
    @kevincozens6837 5 місяців тому +1

    I wouldn't buy a non-working ZX-81 because the most likely source of the problem is the ULA and then good luck getting a replacement.

    • @ezContents
      @ezContents  5 місяців тому

      True. They are hard to find, however I am still thinking of a project where I build an easy to make replacement.

    • @kevincozens6837
      @kevincozens6837 5 місяців тому

      @@ezContents FPGA replacements for the SID chip and the video chip in the C64 have been created. Perhaps someone will create an FPGA based replacement for the ULA.

  • @spacedock873
    @spacedock873 2 роки тому

    Pointless doing the composite mod until it is established that a video signal is being generated in the first place! Since you have an oscilloscope (the same one that I and countless hobbyists have!) that should have been tested before getting the soldering iron out. So, basically the first machine has a dead ULA (very common fault) and so is effectively a junk/donor board and the second one worked out of the box. Yes, Arduino is more appropriate tha n a Pi as a test rig for this generation of machines due to its 5V compatibility. On the ROM adapter it is often possible to push out the unwanted pins from the DIP socket which saves fiddly electrical tape insulation. Always Interesting to see a ZX81 since I helped a friend build his kit version back in the day 😀