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286, SPI, and a 6522 VIA

Updated: Dec 1, 2022

I recently added basic SPI support to my 80286 system with the help of a W65C22S Versatile Interface Adapter (VIA).

Additional Reading About SPI

PSoC Configuration

I am currently using a programmable system-on-chip (PSoC) from Cypress to handle address decoding. Below is the current configuration of the PSoC.


The following schematic is as of 23 November 2022.

Schematic_80286 20221123
Download PDF • 1.09MB

Assembly Code

This assembly I used during this video is available on my GitHub: Assembly Used in Video.

Data Sheets

SPI + Arduino Nano = Serial Debugger

SD Card Support

I have now added support to read from an SD card.

I have an older post that contains some of my previous (troubleshooting) work with SPI and SD cards. See Calling All SPI SD Card Wizards: Troubleshooting SD Card Access with SPI (

The assembly code used in the above video is available here: x86/g1_20221130.asm at main · rehsd/x86 · GitHub.

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