PET 2001 Video Glitch Fix Board

Name: PET 2001 Video Glitch Fix Board
SKU: 36642
Price: 40.00 USD
Availability: InStock

This is a board which solves a problem sometimes seen on early model PETs, where thin vertical lines appear between some characters.

Designed by Tynemouth Software in United Kingdom

2024-11-20T23:09:25.765Z-Pin 3 bypass.jpg

2024-11-20T23:09:25.765Z-Stealth version.jpg

2024-11-20T23:09:25.765Z-Hidden chips.jpg

2024-11-20T23:09:25.765Z-Worse spikes.jpg

2024-11-20T23:09:25.765Z-Right Spikes Zoom.jpg

2024-11-20T23:09:25.765Z-Not a spike in sight.jpg

2024-11-20T23:09:25.765Z-Inverted flip flop glitch removal.jpg

2024-11-20T23:09:25.765Z-Hidden under PET ROM RAM.jpg

2024-11-20T23:09:25.765Z-PET Glitch Fix with 6502.jpg

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This is a board which solves a problem sometimes seen on early model PETs, where thin vertical lines appear between some characters.

What is it? This is a board which solves a problem sometimes seen on early model PETs, one of thin vertical lines appearing between some characters. This can be seen most clearly as what appear to be…

What is it?

This is a board which solves a problem sometimes seen on early model PETs, one of thin vertical lines appearing between some characters.

This can be seen most clearly as what appear to be spikes on top of one or both walls in 3D Monster Maze (https://tynemouth.itch.io/pet-3d-monster-maze) see photos for examples.

Why does it do?

The problem is caused by adjacent inverted and non-inverted characters with pixels up to the edge, and happens on some boards in one or both combinations. The inversion signal changes slightly before or after the character data and causes a small spike on the screen.

This fixes that issues by adding in a pixel clock synchronisation flip flop, so each pixel is sampled in the middle. The output can only change once per pixel clock, so the glitches are removed.

This replaces the 74LS08 chip in position E2 (next to the 6502). The original IC will need to be desoldered and a socket fitted (turned pin socket included). Desoldering on these boards is not for the faint hearted, it is very easy to lift tracks, so proceed with caution unless you are an experienced desolderer.

This is only suitable for the PET 2001 board, as shown in the photos. Not suitable for the 2001N or later.

If you have a PET ROM/RAM board installed, you will need to add an extra 40 pin IC socket into the stack to raise it sufficiently (not included).

This is for the assembled unit only. No PET motherboards, PET ROM RAM boards or anything else is included.

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Tynemouth Software Shipping Policy:

Tracked shipping is recommended on international orders. Parcel will include full value declaration and may be liable to additional delays or customs fees upon arrival. Please be aware of this before ordering, there is nothing I can do about it.