Uploaded December 2018 | Updated September 2026, 3 weeks ago
After replacing the blown filter caps on the power supply board, I wanted to see if the system would power up. Unfortunately, there were other bad caps on the board.
This video was the first one taken, but I had forgotten about it.
After replacing the blown filter caps on the power supply board, I wanted to see if the system would power up. Unfortunately, there were other bad caps on the board.
This video was the first one taken, but I had forgotten about it.

![TRS-80 Model 4 Hi-Res Graphics Upgrade
My TRS-80 Model 4 gets even better with high-resolution graphics! I install Ian Mavrics Improved Grafyx 4.2(.1) HRG board, which is his reproduction of the MicroLabs Grafyx board from the 1980s. After installation, I test some high-resolution software including Post Master, a Slot machine program, and some Graphics BASIC programs. I swear a little more than usual in this video...
Links:
Ian Mavrics Grafyx board site (includes software): http://members.iinet.net.au/~ianmav/hires/hires.htm
Catalog images from RadioShack Catalogs: https://www.radioshackcatalogs.com/flipbook/c1984_rsc-10.html
Music/SFX (in order):
D A T Recorder Fast Forward (Digital Juice)
Corky Dodges Traffic by Richard Ames (Digital Juice)
Video clip:
Rain Main (Four-second Slot Machines clip at 16:10), [official MGM link not found], MGM/UA Communications Co., 1988
Chapters:
Intro / Background (0:00)
Machine Apart / VGA Connector / Gate-Array vs. Non-Gate-Array (1:53)
Installing the Grafyx Card (4:14)
Smoke Test / GBASIC with GTEST/BAS / Spare Parts? (5:19)
Software - GBASIC - Missile (7:22)
Software - Post Master (9:12)
Software - Tournament Chess (13:40)
Software - Slot Machine (15:17)
Software - GBASIC - Tunnel (17:01)
Bonus - Comprehensive HRGTEST/CMD (17:54)
Outro (20:05)
I do these videos unscripted, so I apologize if the in-the-moment descriptions of things are a bit scattered. If you have any questions/comments about this video, you can find me in any of these fine locations:
The Tandy Discord Server
The CoCo Nation Discord Server
The TRS-80 Color Computer (CoCo) group on Facebook
The CoCo Crew Podcast group on Facebook
On the Vintage Computer Forums (vcfed.org)
The TRS-80 Models I-4/4P Group on Facebook
Tandy / Radio Shack Model II /12 / 16 / 16B / 6000 Owners Group on Facebook
Twitter (Im TJBChris there...)
The Level29 BBS (Im TJBChris there, too.)
Particles BBS (Guess who I am here? Yeah, TJBChris.)
Thanks for watching! TRS-80 Model 4 Hi-Res Graphics Upgrade](https://i.ytimg.com/vi/pjbFZ7qUR6k/mqdefault.jpg)








