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Acorn System 1 Replica – Part 3
As a recap, I’ve got a runnable system. Programs can be entered into the systems memory in hex using the keypad and display then executed. However, as it stands there are no additional input or output devices; only the keypad and the LED display and it’s all a bit limiting really. It’s possible to separate…
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Acorn System 1 Replica – Part 2
In the first exciting part of this series we got to the point of a completed design for the CPU board. By this point I’d got a PCB and working system. I realise that I have skipped two topics that need to addressed now. The keypad/display, and an interim solution to the INS8514 I/O device.…
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Acorn System 1 Replica – Part 1
Replicating the CPU board The first problem was to get hold of a schematic and make sure it was correct. On-line I found hi-resolution pictures of both sides of the two PCBs so printed them out, stuck them together and traced each track on the PCBs, comparing it with the schematic and there were a…
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Shift Registers
Shift registers are wonderful things and especially useful to the hobbyist who never seems to have enough I/O pins on the CPU/MPC they want to use. So, with a view to helping explain these misunderstood little scamps, many years ago I wrote this to help explain them, how they work and a practical example of…