An MM/1 appearing in an issue of Rainbow

The IMS Multi Media One, more commonly known as the MM/1, is a computer that was
designed and offered for sale in the early 1990s. Seen as one of the successors to the Tandy Color Computer line, it was offered as a kit, due to a lack of FCC approval (emissions).

Though the MM/1 was not at all compatible with the Color Computer line, it did run a version of OS9 (OS9 68K) and was seen as a new machine for those using the OS9 operating system in the Color Computer community.

Not many were made, 500 or less is the only information on the number produced that I can find reference to. Probably not surprising, considering the lack of FCC approval, the kit format, and the limited following of OS9.

The computer uses the same CPU and video controller that the Phillips CD-i system was based on, the SCC68070 and SCC66470, respectively.

In late 2015 I acquired a working MM/1 computer from Michael Knudsen, a known software developer on the MM/1 scene back in it’s time. Of course, I had to take it apart as soon as I verified that it worked.

Other than the case, power supply, and drives, the computer is composed of three main circuit boards; the CPU board, an I/O board, and a “Minibus” board which ties them together and provides the power connections for the boards.

The CPU board is on the bottom, ports at one end of the boards are positioned to the rear of the case, and the Minibus connects them at the front.

View of the system boards as attached (I/O board at top)

The CPU board itself carries the ROM to boot the system, serial port, RGB video out, keyboard port, floppy disk controller, and the Video controller IC. The I/O board provides an additional serial port, RAM (in SIMMs), real-time clock, SCSI controller, and other I/O.

MM/1 CPU / Video controller board

MM/1 Minibus

Rear view of the MM/1 system boards, showing I/O ports