Home built Spectrum 128

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The Sinclair spectrum is a relatively simple computer and only really uses one custom part, the ULA. As i had one of these lying around, i decided to try to use it to build one.

The process of building in order

Building and testing the video mixer

Building and testing the Chroma section

ULA and lower ram section and testing

Adding the CPU and ROM

Spectrum Keyboard

At this stage, we now have a working and usable 16K spectrum. Of course, being a 16K spectrum, its not useful for very much, but you cant have everything :-)

Power supply

Speaker and audio

48K ram

128k Ram paging

128k ROM paging

Modification for rom selection

Keyboard joysticks

Replacing the Dimm with SRAM

Spectrum 128 Audio

Still to do

  • The CPU is too loaded and is unstable when all the cards are plugged in. Must put in some buffers.
  • Shadow video ram.
  • Multiface hardware
  • Spectrum +2a/+3 ROM system
  • Hard disk hardware
  • Kempston mouse
  • Kempston joystick