Processor Technology Sol-20 wth Helios Disk System The Sol-20 computer was made by Processor Technology in the 1977 and it was considered the most “elegant and best designed computer” of the early systems. A prototype of the SOL-20 was the cover story of the July, 1976 issue of Popular Electronics. Bob Marsh, co-founder, also appeared on the Today Show demonstrated the Sol-20 playing a video game. The SOL-20 was introduced in June 1976 at the PC'76 Computer Conference. The SOL-20 was designed by Lee Felsenstein, who also was one of the founders of the Community Memory Project, the Homebrew Computer Club from 1975-86, and also designed the Osborne 1 and other micro computers. Features: 8080 CPU, 2Kb ROM operating system on a plug-in “Personality Module”, 1Kb of RAM (note: the ROM operating system boots with no additional memory), 64x16 line video display with hardware scrolling, cassette tape I/O, RS-232 serial port, parallel port (not PC compatible, but can be adapted to support most PC printers), 85-key Keytronics keyboard, 5-Slot S-100 bus card cage Out of the box the Sol-20 was just a smart terminal, but functional with it’s ROM-based(Solos) operating system ). By simply adding an S-100 memory card and floppy disk controller it became a real computer capable of running CP/M disk operating system, or PTDOS, the Processor Technology system. The Helios disk system and “PTDOS” were Processor Technology’s disk solution. The market at that time was using CP/M, and PTDOS/Helios were never really accepted. (both of which used wierd hard-sector diskettes). The 8" Persci drives were also plagued with reliability problems and failure.   Helios is an enclosure and power supply for dual Persci (Peripheral Sciences) 8" floppy disk drives. At the time the Helios was very attractve compared to other disk subsystems.The Persci drive was the fastest floppy ever built using a state-of-the-art 1 msec voice coil. However is was over-priced at $1500, unreliable and Persci eventually went out of business.   The controller for the Helios was a 2-card set. It used DMA (direct memory access), which was way ahead of it’s time, and hard sectored disks, neither of which were common for that era. There was also a Processor Tech newsletter published called 'SOLUS'. This computer is now in a new museum and not part of our collection.