4 open source boards using the 6821
Real designs built with the 6821, from public GitHub projects: a quick way to see how others power, decouple and connect it. Each board comes with its KiCad files, full parts list and a render — and you can simulate its firmware on HardLabs.
Dragon64
danwerner21
333.2 × 205.9 mm220 parts2LNo license34
TRS-80 Color Computer 2 NTSC ( 26-3134B & 26-3136B)
qbancoffee
230 × 170 mm150 parts2LGPL-3.040
Backup
333.2 × 205.9 mm218 parts2LNo license34
Backup1
333.2 × 205.9 mm218 parts2LNo license34
The 6821 in open source designs
The gallery holds 4 open source boards using the 6821 from 2 GitHub repositories; a typical one measures about 333.2 × 205.9 mm and carries around 218 components.
100% are two-layer designs, the rest use four layers or more, and 25% carry an open source license.
The most starred is TRS-80 Color Computer 2 NTSC ( 26-3134B & 26-3136B) by qbancoffee.
6821: common questions
Where can I find a 6821 reference design?
Each of the 4 boards on this page is a real design using the 6821. Open one to see how it is wired up, with the full BOM, a render of the layout and links to its KiCad files.
What parts are used alongside the 6821?
The 27C128, 74LS02, 74LS138 and MC6809E appear in the most repositories here.
How big is a typical board using the 6821?
The median is 333.2 × 205.9 mm, and 100% are two-layer designs.
What is the most popular open source board using the 6821?
By GitHub stars, TRS-80 Color Computer 2 NTSC ( 26-3134B & 26-3136B) by qbancoffee, with 40 stars.
Can I simulate one of these boards using the 6821 before building it?
Yes. HardLabs turns a board's netlist and BOM into a working simulation, so you can boot and test firmware against it with no hardware on your desk.