When it comes to software, computers these days spoil us. All you need to do is download a program from the internet to your hard drive, install it to the same hard drive, and run it. But, things were different in the ’80s — storage space was extremely limited, and there was no internet to download software from. A common solution was to provide software on hardware ROM cartridges, kind of like video games for home consoles. If you have an Acorn Electron, you can now emulate those ROM cartridges with an STM32F4.
This project comes to us from KernelCrash, and it should cost less than $20 to implement thanks to the many affordable STM32F4 development boards on the market. When you run software on an Acorn Electron from a ROM cartridge, the computer is expecting the ROM chip to act in a precise way. The data needs to be presented in the correct format, and that needs to happen with specific timing.
To make that work, the KernelCrash Electron ROM Emulator was written in Arm assembly code. That allows for the low-level control that’s necessary for successfully tricking the Acorn Electron into thinking it’s reading from hardware ROM. After installing the emulator code to your STM32F4, you can use jumper wires to connect the IO pins to a 50 pin edge connector that fits the Electron’s ROM slot. ROM files can then be converted and stored on the STM32F4’s flash memory, or on an SD card. Just boot up your Electron and select the ROM file to load, and you can start running your software!