I have main unit.
type computer
country USA
year 1976
os Console OS
cpu Intel 8080
speed MHz
ram 8 to 48 KB
graphic 64 x 16 character text
colors mono
sound no
ports RS-232, cassette in/out, S100 Bus
The Processor Technology SOL-20 — The Beautiful Early Microcomputer
The Processor Technology SOL-20, released in 1976, was one of the most elegant and capable early microcomputers — a complete, self-contained computer with a built-in keyboard, video output, and cassette interface at a time when most microcomputers were bare circuit boards requiring significant user assembly and external peripherals. Designed by Lee Felsenstein (who would later design the Osborne 1) and Bob Marsh, the SOL-20 was built around the Intel 8080 processor and used the S-100 bus — the standard expansion bus of the mid-1970s hobbyist computing community.
Lee Felsenstein’s Design
Lee Felsenstein was one of the most important engineers of early personal computing. He designed the SOL-20, later designed the Osborne 1 (the first portable computer), and was a central figure in the Homebrew Computer Club — the legendary group in Silicon Valley whose members included Steve Wozniak and many other pioneers of the personal computer revolution. Felsenstein’s design philosophy emphasised completeness and usability, and the SOL-20 reflected this: where the Altair 8800 was a kit of blinking lights requiring significant technical expertise, the SOL-20 was a machine that could actually be used productively out of the box.
The S-100 Era
The SOL-20’s S-100 bus connected it to the ecosystem of expansion boards and peripherals that had grown around the Altair 8800 — memory boards, I/O interfaces, disk controllers, and other hardware that hobbyists and early businesses used to build capable computing systems. The S-100 bus represented the first serious attempt at a standard expansion architecture for personal computers, predating the ISA and PCI buses that would later standardise PC expansion. Surviving SOL-20 machines are rare and historically precious, representing personal computing at its very beginning.