Xerox Alto

The Alto, built by Xerox' Xerox PARC laboratory, was a ground-breaking and extremely influential personal computer - in fact, all contemporary personal computers are descendants of the Alto.

The Alto was novel in that each machine had a bit-mapped display, allowing the creation of a graphical user interface, and was also attached to a high-speed network, the Ethernet, also invented at PARC.

The CPU was microcoded, built out of TTL, and could emulate several different CPUs - the basic ROM more or less emulated a Data General Nova. The CPU did not support DMA; rather, it had provision for up to 16 micro-tasks, which did all bulk input/output.

Altos all had a 1.25Mbyte disk drive from Diablo Systems (the same drive as in the RK02 disk drive); Alto-based file servers used Trident disk drives.

Xerox attempted to commercialize the lessons of the Alto, in the Xerox Star, but it was not a commercial success. Other companies, including IBM (hardware), Microsoft (software) and Apple (both) did manage to produce succesful products along the lines pioneered by the Alto.