Tag: Acorn System 1

  • Acorn System 1 Replica

    This was a mammoth project and isn’t actually finished although it does work. I’m not going into the background of the Acorn System 1 as those who know about this microcomputer are well aware of it’s history. Originally this rebuild project was a series of many blog entries describing how I got to a working […]

  • Acorn System 1 Replica – 19″ Rack

    The System 1 starts out as two euro cards stacked one on top of the other; CPU at the bottom with Keypad/Display on the top. It’s nice, compact and very pretty, but rather useless as soon as you want to start hooking it up to things. Quickly you realise that you are going to need […]

  • Acorn System 1 Replica – Eurocard extender

    During expansion card development, it’s handy to be able to poke around the card with an oscilloscope or multi-meter probe, but you can’t do that when the card is seated in it’s home position in the rack. The euro extender card plugs into the backplane slot, and then allows the expansion card to be plugged […]

  • Acorn System 1 Replica – SAD

    The Segment Address Decoder (SAD) The 6502 CPU has no special I/O instructions or hardware support signals; unlike the Z80 CPU for example, so for the most part any expansion boards need to occupy one or more addresses within the 64K memory map. In the 6502 world, hardware is usually classed as “memory mapped”. Whilst […]