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Building The ZX Raspberry – Part Four

In which our hero is unable to leave well alone

A little epilogue to the ZX Raspberry project. I came into possession of a very dead ZX Spectrum+ and, following my own personal rule of ‘it gets fixed or it gets modded’, I decided that it was time for a ZX Raspberry+. This project did away with the USB keyboard option, so just a standalone Raspberry Pi-driven unit.

ZX Raspberry+ Innards
ZX Raspberry+ Innards

I made a few improvements and discoveries along the way.

  1. It’s a lot easier to put all this gubbins in a Plus case rather than an original.
  2. The Raspberry PI + variant (+ or 2) is conveniently sized to place the HDMI and power alongside the expansion port (less cables!).
  3. The +’s reset switch makes a handy keyboard mode switch.
  4. A conclusion I reached during the first project was right, I didn’t need the resistors on KB1. Leave them and the power line out, wire the connector directly to the Pro Micro and just set the inputs to INPUT_PULLUP in the Arduino sketch. It does everything for you.

Finally, I was able to really speed up boot time by using PipaOS instead of the standard Rasbian distribution. It’s still Raspbian, but optimised for fast bootup and without a lot of the stuff you don’t need anyway. The results on a Raspberry PI 2 with a Class 10 SD card are quite something. Here’s a boot video:

Just a shade over 10 seconds. Not bad eh?

Published inMakesRaspberry PiVintage Tech

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