Posted: January 18, 2016

Introduction

The purpose of this project is to create a graphics / sound demo in Java and run it on a TRS-80 Coco2 computer.

A while ago I was given a Radio Shack TRS-80 Coco2 computer. Since this computer runs on a Motorola 6809 CPU, I decided over the weekend to add support for it in naken_asm and then also Java Grinder. It's not finished yet, but there is enough code and API to create a small demo. Not sure how far I'll take it since this computer has been unsupported for years.

Kind of an interesting computer though. It kind of reminds me a lot of the TI99/4a in that the graphics feel pretty primitive and such. The TI99/4a's CPU (the TMS9900) is in a way nicer since it's full 16 bit, with a 16 bit multiply even. The 6809 has a much fuller instruction set with some 16 bit support, but mostly just 8 bit. It's actually a lot like a souped up 6502 chip. The graphics and sound support in it kind of lacks compared to the TI99/4a (the TI99/4a at least has sprites) and definitely doesn't come close to the Commodore 64.

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Video

Full video: https://youtu.be/DtKaRVFgVGk

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