Mac to the Future

The MicroMac is a tiny original Macintosh clone that uses a $4 Raspberry Pi Pico to emulate the 68000 CPU and System Software 1.0 OS.

Nick Bild
30 days agoRetro Tech
The MicroMac emulates the original Apple Macintosh (📷: Matt Evans)

The computers of yesteryear are in many ways much more fun to hack on than today’s machines. Whether it was equipped with a 6502, Z80, or other early microprocessor, the abundance of discrete through-hole chips on circuit boards with traces large enough to drive a truck through made these systems quite easy to understand and modify. Try that with a modern Intel Core i9-based system!

To be sure, the fog of time has made these computers of the early personal computer revolution seem more attractive than they really are. After all, they are saddled with severe hardware limitations and some major usability concerns. But while no one wants to use them as their daily driver anymore, there is no use in trying to reason with a retro computer enthusiast singing their praises. A word to the wise: if you come across a group of them in the wild shouting “Commodore forever!,” simply smile and back away slowly. Whatever you do, make no effort to reason with them.

Electronics hobbyist Matt Evans is particularly fond of the original Apple Macintosh personal computer, with its Motorola 68000 microprocessor, 128 KB of RAM, and monochrome display (remember: make no effort to reason with them!). Needless to say, this is a scant amount of computational power by modern standards. That set Evans to thinking about how inexpensively and simply one could reproduce such a system today. The answers: a few dollars and a lot of effort, respectively.

Evans designed and built a diminutive bare bones clone of the original Macintosh, called the MicroMac, using only modern hardware and techniques. It is built around the $4 Raspberry Pi Pico microcontroller development board — not too bad, considering the real deal initially cost nearly half as much as a compact car. The Pico emulates the 68000 microprocessor, the Macintosh hardware, outputs a VGA signal (in a beautiful 512 x 342 pixel monochrome), and accepts keyboard and mouse inputs.

To avoid going down a huge rabbit hole, Evans made use of an existing 68000 CPU emulator called the Musashi 68K interpreter. This C-based tool provided a platform on top of which to build an emulator for the System Software 1.0 operating system. This took the form of a custom emulator named umac that was written by Evans. It is described as having the absolute minimum in hardware emulation, such that it can boot and run some basic apps. So it gets the job done, but may not please hardcore retro computing enthusiasts.

The original system may have run at 7.8336 MHz, but emulation is far less efficient than real hardware, so even the much more advanced Pico processor running at up to 133 MHz could not match the speed of the original computer. Fortunately the Pico is well known for its ability to be heavily overclocked, so Evans simply cranked it up to 250 MHz to bring the MicroMac up to speed.

The amount of work that goes into building a MicroMac might make you rather just buy an original machine from EBay instead of building a modern reproduction. But since Evans has already done all of the dirty work, and documented it in detail, it should not be too difficult to make a MicroMac from that Pico that is already in your parts drawer. If you do, be sure to post it here on Hackster. We would love to drool over it!

Nick Bild
R&D, creativity, and building the next big thing you never knew you wanted are my specialties.
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