W65C265S Primary + AV Boards
- rehsd
- Feb 7
- 2 min read
Updated: Mar 20
Continuing my W65C265S project series, I am at a nice milestone where I have a second version of a PCB (actually, a pair of PCBs) -- with significantly expanded functionality from my first PCB. For more background on my work on this up to this point, check out rehsdonline.com/post/w65c265s-single-board-computer. My goal in this post is to work through the two PCBs in the rendering below.
This post will be updated as I work through the design and build.
[February 07, 2026] I have received in the 'Primary' PCB, the lower of the two boards in the image above.
Tone Generators
Code for the video above is available at microcontollers/W65C265S/Primary AV Boards/Tone Generator 20260209 at main · rehsd/microcontollers · GitHub
Maybe a lightweight operating system?
Code for the above video: microcontollers/W65C265S/Primary AV Boards/65265_Primary R265Nibbler v0.01 -20260211 at main · rehsd/microcontollers · GitHub.
VGA
For my VGA on the AV board, see the VGA page in the AV schematic (below in this post). To support this VGA circuit design, I have three GAL22V10D ICs (PLCC package). I have posted the logic for the GALs under Schematics below, too. As of this point in my build, the snapshot of code and schematics (both Primary and AV boards) are available here.
Audio
Related: Sound Card for my 286 System
Parallel Interface Bus (PIB)
SPI Real-time Clock
Code for the above video available here: microcontollers/W65C265S/Primary AV Boards/65265 assembly FULL 20260312 - SPI RTC at main · rehsd/microcontollers.
SD Card
Code for the above video available here: microcontollers/W65C265S/Primary AV Boards/65265 assembly FULL 20260320 - SD Card at main · rehsd/microcontollers.
More to come!
Schematics
Decode logic for AV board, including VGA:
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