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Johan Koelman

ZX81-coder, 1K hires games (That's is Hires games in 1K screen included)

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johan-koelman

This user joined on 12/27/2016.

Things I've Built

Shift-Add-multiply marble computer

First and only marblecomputer that, unlike Digicomp-II, can multiply with shift add method and not repeating additions.

6 digit BCD interface for marblecomputer

Marble computer that can add up to 63. Added a BCD-interface (with full-adders) to display correct number.

ZX Spectrum PC Interface

speed load from PC to ZX Spectrum over parallelport

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