Fujitsu FM-7

~ the eulogy ~

Fujitsu's home computer was the FM-8, and the FM-8 was too expensive. So the company built a cheaper one by taking parts out of it. The project was called FM-8 Jr. inside the building, it went on sale on 8 november 1982 as the FM-7 at 126,000 yen, and it did what cut-down variants occasionally do, which is stop being the cheap alternative and start being the product. It shipped 220,000 units, and it is the reason Japanese magazines began listing Fujitsu alongside NEC and Sharp as one of the three companies that mattered in personal computers.

The thing it kept from the FM-8 is the thing worth remembering. The FM-7 had two Motorola 6809 processors, running at 2 MHz, and only one of them was the computer. The other existed to drive the display subsystem and nothing else, with the two halves passing work between them through shared memory. In 1982 the normal number of processors in a home computer was one, and the normal way to draw a screen was to make that one processor do it in whatever time was left over. Fujitsu had already decided that pixels deserved their own silicon. It also had a better sound chip than the FM-8, which is a large part of why hobbyists preferred it to the machine it was cheaper than.

It did not last long as a model. The original FM-7 came off the list in april 1984, and in may Fujitsu shipped the FM-NEW7 at 99,800 yen, which was the same computer built down to a lower cost. The FM-77 arrived alongside it with a detached keyboard and 3.5 inch floppy drives, and the FM77AV line carried the architecture as far as 1988. Then Fujitsu stopped iterating on it and built the FM Towns instead, a 32-bit machine with a CD-ROM drive in it, which is a different grave. The FM-7's own life on the price list was seventeen months.

Neither of these machines was sold in Turkey, so I am reading this off Japanese sources rather than remembering it. What travels is the decision. Fujitsu built a flagship, then built a cheaper machine by removing things from it, and the cheaper machine is the one that sold and the one every successor was named after. Every hardware team I have worked on has had some version of that argument, and the stripped variant usually wins for a reason nobody enjoys saying out loud: the removed features tend to be the ones the engineers found interesting and the customer never asked about. Bubble memory was genuinely exotic in 1982. It was also the first thing to go.

~ the dossier ~

~ two processors ~

The dual 6809 design came from the FM-8 and stayed in the family through the FM77AV. One 68B09 was the main CPU and one was the display subsystem, and software that wanted to do something clever with graphics was really writing for two machines that had to agree with each other. Programmers of the era describe it as awkward, which it was, and as fast when you got it right, which it also was.

It is a familiar shape from where I sit now. Putting a second processor next to the first one because the first cannot keep up with the pixels is the whole ancestry of the graphics card, and after that of every accelerator sitting on a board next to a CPU doing one narrow thing extremely quickly. Fujitsu was doing it in a beige box aimed at Japanese hobbyists two years before the Macintosh shipped, and the awkward part, which is getting two processors to share memory without stepping on each other, is still the awkward part.

~ what was taken out ~

The list of what Fujitsu deleted from the FM-8 to make the FM-7 is a decent summary of what 1982 thought was optional. Out went the bubble cassette holder, which was the slot for magnetic bubble memory, a solid-state storage technology that looked like the future for about five years and then lost completely to cheaper disks and cheaper RAM. Out went the RS-232C serial port, along with the analog input port that on the FM-8 had mostly been used for joysticks, and Fujitsu ended up selling an add-on to put the joystick port back for the people who noticed.

What went in, or rather what stayed, was an optional Z80 card that let the machine run CP/M. That is a real tell about who Fujitsu thought was buying: a home computer priced at 126,000 yen with the serial port removed to save money, sold alongside an accessory that turns it into a business machine for anyone who wants that. The FM-7 sold to hobbyists in the end and Fujitsu spent the next seven years building better versions of it for the same people.

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