TRS-80 Model 100 Accelerator

Introduction

Lets you SSH into the Raspberry Pi terminal with the TRS-80 Model 100, by providing RS-232 conversion to the Pi's GPIO pins. Includes a boot/shutdown switch for the Pi.

The idea for this project is to make the TRS-80 Model 100 usable like a modern linux PC. The Raspberry Pi Zero W is actually tunning the terminal, and any applications, you're simply SSHing into a terminal session using RS-232. There is a serial port on the back side of the TRS-80 Model 100 that the accelerator board plugs directly into (a DB-25 connector). The accelerator board is laid out as a 'hat' module for the Raspberry Pi Zero W. The board uses the common MAX3232 to shift between the standard RS-232 -+12v serial signal to the more modern 3.3v serial voltage of the Raspberry Pi Zero W UART. I also incorporated a combination hardware/software power button for the Raspberry Pi Zero W, so it can be easily and safely started and shut down. The board does not include batteries, but input power (from a battery bank with 5v regulation) goes to the Micro USB B female, and power output (to the Raspberry Pi) is a full sized USB A female.

PCB is available on Altium Circuitmaker. Prototype assembly and testing is under way.