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Sol-20
The Sol-20 was the first fully assembled microcomputer with a built-in keyboard and television output, what would later be known as a home computer. The design was the integration of an Intel 8080-based motherboard, a VDM-1 graphics card, the 3P+S I/O card to drive a keyboard, and circuitry to connect to a cassette deck for program storage. Additional expansion was available via five S-100 bus slots inside the machine. It also included swappable ROMs that the manufacturer called 'personality modules', containing a rudimentary operating system.
The design was originally suggested by Les Solomon, the editor of Popular Electronics. He asked Bob Marsh of Processor Technology if he could design a smart terminal for use with the Altair 8800. Lee Felsenstein, who shared a garage working space with Marsh, had previously designed such a terminal but never built it. Reconsidering the design using modern electronics, they agreed the best solution was to build a complete computer with a terminal program in ROM. Felsenstein mentioned on a recent interview that the name of the Sol was inspired after Les Solomon, Technical Editor of Popular Electronics .
The Sol appeared on the cover of the July 1976 issue of Popular Electronics as a "high-quality intelligent terminal". It was initially offered in three versions; the Sol-PC motherboard in kit form, the Sol-10 without expansion slots, and the Sol-20 with five slots.
A Sol-20 was taken to the Personal Computing Show in Atlantic City in August 1976 where it was a hit, building an order backlog that took a year to fill. Systems began shipping late that year and were dominated by the expandable Sol-20, which sold for $1,495 in its most basic fully-assembled form. The company also offered schematics for the system for free for those interested in building their own.
The Sol-20 remained in production until 1979, by which point about 12,000 machines had been sold. By that time, the "1977 trinity" —the Apple II, Commodore PET and TRS-80— had begun to take over the market, and a series of failed new product introductions drove Processor Technology into bankruptcy. Felsenstein later developed the successful Osborne 1 computer, using much the same underlying design in a portable format.
Lee Felsenstein was one of the sysops of Community Memory, the first public bulletin board system. Community Memory opened in 1973, running on a SDS 940 mainframe that was accessed through a Teletype Model 33, essentially a computer printer and keyboard (a hard copy terminal that prints both input and output), in Leopold's Records record store in Berkeley, California. The cost of running the system was untenable; the teletype normally cost $1,500 (their first example was donated from Tymshare as junk), the modem another $300, and time on the SDS was expensive – in 1968, Tymshare charged $13 per hour (equivalent to $118 in 2024). Even the reams of paper output from the terminal were too expensive to be practical and the system jammed all the time. The replacement of the Model 33 with a Hazeltine glass terminal helped, but it required constant repairs.
Since 1973, Felsenstein had been looking for ways to lower the cost. One of his earliest designs in the computer field was the Pennywhistle modem, a 300 bits per second acoustic coupler that was 1/3 the cost of commercial models. When he saw Don Lancaster's TV Typewriter on the cover of the September 1973 Radio Electronics, he began adapting its circuitry as the basis for a design he called the Tom Swift Terminal, a reference to the fictional scientist and inventor of the same name. The terminal was deliberately designed to allow it to be easily repaired. Combined with the Pennywhistle, users would have a cost-effective way to access Community Memory. Marsh and Felsenstein reconnected once Marsh finished building his TV Typewriter in 1974. When Felsenstein saw it, he began to design his own terminal, which he hoped to deploy as a replacement for Community Memory teletypes.
In January 1975, Felsenstein saw a post on Community Memory by Bob Marsh asking if anyone would like to share a garage. Marsh was designing a fancy wood-cased digital clock and needed space to work on it. Felsenstein had previously met Marsh at school and agreed to split the $175 rent on a garage in Berkeley. Shortly after, Community Memory shut down for the last time, having burned out the relationship with its primary funding source, Project One, as well the energy of its founding members.
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Sol-20
The Sol-20 was the first fully assembled microcomputer with a built-in keyboard and television output, what would later be known as a home computer. The design was the integration of an Intel 8080-based motherboard, a VDM-1 graphics card, the 3P+S I/O card to drive a keyboard, and circuitry to connect to a cassette deck for program storage. Additional expansion was available via five S-100 bus slots inside the machine. It also included swappable ROMs that the manufacturer called 'personality modules', containing a rudimentary operating system.
The design was originally suggested by Les Solomon, the editor of Popular Electronics. He asked Bob Marsh of Processor Technology if he could design a smart terminal for use with the Altair 8800. Lee Felsenstein, who shared a garage working space with Marsh, had previously designed such a terminal but never built it. Reconsidering the design using modern electronics, they agreed the best solution was to build a complete computer with a terminal program in ROM. Felsenstein mentioned on a recent interview that the name of the Sol was inspired after Les Solomon, Technical Editor of Popular Electronics .
The Sol appeared on the cover of the July 1976 issue of Popular Electronics as a "high-quality intelligent terminal". It was initially offered in three versions; the Sol-PC motherboard in kit form, the Sol-10 without expansion slots, and the Sol-20 with five slots.
A Sol-20 was taken to the Personal Computing Show in Atlantic City in August 1976 where it was a hit, building an order backlog that took a year to fill. Systems began shipping late that year and were dominated by the expandable Sol-20, which sold for $1,495 in its most basic fully-assembled form. The company also offered schematics for the system for free for those interested in building their own.
The Sol-20 remained in production until 1979, by which point about 12,000 machines had been sold. By that time, the "1977 trinity" —the Apple II, Commodore PET and TRS-80— had begun to take over the market, and a series of failed new product introductions drove Processor Technology into bankruptcy. Felsenstein later developed the successful Osborne 1 computer, using much the same underlying design in a portable format.
Lee Felsenstein was one of the sysops of Community Memory, the first public bulletin board system. Community Memory opened in 1973, running on a SDS 940 mainframe that was accessed through a Teletype Model 33, essentially a computer printer and keyboard (a hard copy terminal that prints both input and output), in Leopold's Records record store in Berkeley, California. The cost of running the system was untenable; the teletype normally cost $1,500 (their first example was donated from Tymshare as junk), the modem another $300, and time on the SDS was expensive – in 1968, Tymshare charged $13 per hour (equivalent to $118 in 2024). Even the reams of paper output from the terminal were too expensive to be practical and the system jammed all the time. The replacement of the Model 33 with a Hazeltine glass terminal helped, but it required constant repairs.
Since 1973, Felsenstein had been looking for ways to lower the cost. One of his earliest designs in the computer field was the Pennywhistle modem, a 300 bits per second acoustic coupler that was 1/3 the cost of commercial models. When he saw Don Lancaster's TV Typewriter on the cover of the September 1973 Radio Electronics, he began adapting its circuitry as the basis for a design he called the Tom Swift Terminal, a reference to the fictional scientist and inventor of the same name. The terminal was deliberately designed to allow it to be easily repaired. Combined with the Pennywhistle, users would have a cost-effective way to access Community Memory. Marsh and Felsenstein reconnected once Marsh finished building his TV Typewriter in 1974. When Felsenstein saw it, he began to design his own terminal, which he hoped to deploy as a replacement for Community Memory teletypes.
In January 1975, Felsenstein saw a post on Community Memory by Bob Marsh asking if anyone would like to share a garage. Marsh was designing a fancy wood-cased digital clock and needed space to work on it. Felsenstein had previously met Marsh at school and agreed to split the $175 rent on a garage in Berkeley. Shortly after, Community Memory shut down for the last time, having burned out the relationship with its primary funding source, Project One, as well the energy of its founding members.
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