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  • Writer's picturerehsd

Prepping My 6502 System for FPGA VGA

Updated: Feb 11, 2022

I made some updates to my 6502 system to get it ready for my FPGA VGA. Previously, my USB mouse took ten VIA pins (a bit of laziness on my part). I cleaned up the design a bit and pulled the pin count needed to support the USB mouse down to six pins (four pins to cover the eight directions of the mouse, and two pins to cover the three buttons), so it fits on a single VIA port. I then relocated the USB mouse connection to VIA2 and updated all of the 6502 assembly to go with these changes. This completely freed up VIA5. I plan to use VIA5 for my FPGA VGA (soon) -- it will require both ports of VIA5. I think I could use more VIA ports. 😂

  • VIA1: Two-line LCD and PS2 keyboard

  • VIA2: USB mouse and SPI

  • VIA3: SPI

  • VIA4: Sound card


If I spin another 6502 PCB, I will include the improved reset circuit (upper left corner), remove the current onboard VGA circuit (lower left corner), include the FPGA VGA circuit, and maybe add another VIA or two. I guess I'm going with, "you can never have too many VIAs." 😎

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