Emulating 27xx series programmable ROMs with an RP2040 board

PicoROM is an 8-bit ROM emulator in a DIP-32 compatible form factor. Its main use case is for rapid iteration when experimenting with arcade hardware. The PicoROM can emulate ROMs up to 2MBit (256Kbytes) in size and access times of 70ns. Its size allows it to fit into almost any ROM socket regardless of how crowded the board might be.

Feature Summary

  • DIP-32 form factor
  • 2MBit (256KByte) storage
  • 70ns access time
  • USB or board powered
  • Reset line

A PicoROM is controlled by the picorom tool on a PC via the USB connection. The picorom tool allows you to list PicoROMs attached to the system, rename them, set parameters and (most important of all) upload ROM data. Each PicoROM device has a name that is used to identify it when running commands. It is not uncommon to have multiple devices connected at once and want to send different data to each one. Arcade boards often have multiple ROMs to both increase the total memory size, to increase the bus width or both.

Fully-assembled units are available to buy on the Peanut Butter Retro Tindie store at $25 each.

See the files on GitHub (under an MIT license) and more in the hackster.io article here.

And see more in the video below:


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