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Showing results for tags 'expansion bus'.
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Maybe someone at sometime will find this info useful. The Model III and 4 has a single 50 position I/O bus port for expansion. A company called Alpha Products used to sell a cable that allowed you to daisy chain multiple peripherals on that port. Unfortunately those haven't been available since the mid 80s. The port is a 50 position card edge. 50 position ribbon cable and female connectors are easily sourced. Amazon has the best price on the female connectors; less than $20 for 5. Anything with a 50 position card edge is next to impossible to find these days. Also each "finger" on the board needs to connect from top on one side to bottom on the other. The Radio Shack Hi-Res board came with one as a pass through. I recently found a source for dirt cheap prototype trans boards that can be modified in about 1 minute. https://www.circuitspecialists.com/pc622.html Syntax PC-622. These are 62 position and already have the reverse side connected. A cutting wheel on a Dremel will easily make it into a 50 position. You'll also want to bevel the edge a bit with a flat file. My port currently has the Hi-Res board (looped from inside like factory), FreHD (hard drive) and an Orchestra 90 all getting along together. I also have a mouse interface for CAD which I'll try as soon as I get a RS mouse.
I recently bought a lot of 5 99 4A's on Ebay that all had issues.So far, i've gotten 3 running. Two are perfect as far as i can see- they see the FinalGROM and the 32k sidecar(shorty from Arcadeshopper) with no problem and I can run all the FG programs that don't require F18A. The Third unit boots up fine with no FG or 32k sidecart and with the FG but no 32k sidecar, but if I include the side car, it boots to a loud noise and a black screen. Any ideas on what I should look at?