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ROSCO M68K Kit

ROSCO M68K is a single-board 16/32-bit computer built using retro components. Its main value is educational. The board is well suited for learning core computer science principles, applied programming, and low-level development thanks to minimal abstraction and a transparent architecture.

The 16/32-bit designation is not marketing. The Motorola 68000 CPU features:

  • 32-bit registers
  • a 16-bit data bus
  • a 24-bit address bus

This is why the system combines characteristics of both 16-bit and 32-bit computers.

What is the ROSCO M68K Kit

The ROSCO M68K Kit is a do-it-yourself kit for assembling a rosco_m68k computer without having to go through the entire process of sourcing, selecting, and adapting retro components.

Building such a computer from scratch today is non-trivial:

  • the Motorola 68000 has not been manufactured for almost 30 years
  • some components are still available (PLD, RAM, ROM), but finding an original UART is difficult
  • you have to search for substitutes, adapt firmware, and accept limited speeds
  • ROM can still be programmed using simple tools (even Arduino), but PLDs require a dedicated programmer
  • PCBs cannot be ordered as a single unit — minimum batches are usually 5 boards or more

The main value of the kit is simple: you avoid all of these problems.
You assemble a working computer and focus on the process and the result, not on logistics and component scarcity.

If you run into issues, you can contact me directly — I’ll try to help with diagnostics and bring-up.

Architecture overview

The system is built around the Motorola 68000 processor:

  • 32-bit registers
  • 16-bit data bus
  • 24-bit address bus

The configuration includes:

  • 1 MB Flash ROM — bootloader and system data
  • 1 MB SRAM — main system memory

All peripherals are connected via memory-mapped I/O.

The serial interface is implemented using the SCN68681 DUART with a dedicated 3.6864 MHz crystal, providing a stable RS-232 connection for console access and debugging.

Address decoding and control signal generation are handled by an ATF22V10 PLD, acting as glue logic between the CPU, memory, and peripherals.

The board is intentionally simple:

  • no SoC
  • no DMA
  • no complex controllers

Only the essentials: CPU, memory, UART, and logic.
All key ICs are socketed, making the system suitable for learning, experimentation, and low-level development.

Kit versions

There are two versions of rosco_m68k:

  • THT (through-hole)
  • SMD

Soldering small SMD components is often challenging: parts shift under hot air, alignment issues occur, and quality control is harder.
The THT version avoids these problems — all components are large and convenient for manual soldering.

Currently available in the store:

  • THT version as a kit
  • SMD version fully assembled
THT version SMD version

What’s in the box

The kit includes all required components to assemble the board:

  • Motorola 68000 CPU
  • SRAM
  • ROM
  • UART
  • IC sockets
  • passive components (resistors, capacitors, buttons)
Demo kit version