Reconsidering the design using modern electronics, they agreed the best solution was to build a complete computer with a terminal program in ROM.

[2] 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.

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.

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, in a record store in Berkeley, California.

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.

Shortly after, Community Memory shut down for the last time,[14] having burned out the relationship with its primary funding source, Project One, as well the energy of its founding members.

[5] January 1975 was also the month that the Altair 8800 appeared on the front page of Popular Electronics, sparking off intense interest among the engineers of the rapidly growing Silicon Valley.

[17] Marsh began offering Felsenstein contracts to draw schematics or write manuals for the products they planned to introduce.

[20][h] Before the VDM-1 was launched in the fall of 1975, the only way to program the Altair was through its front-panel switches and LED lamps, or by purchasing a serial card and using a terminal of some sort.

[22] Les Solomon, whose Popular Electronics magazine launched the Altair, felt a low-cost smart terminal would be highly desirable in the rapidly expanding microcomputer market.

In December 1975, Solomon traveled to Phoenix to meet with Don Lancaster to ask about using his TV Typewriter as a video display in a terminal.

[22] The two immediately began arguing when Lancaster criticized the design of the Altair and suggested changes to better support expansion cards, demands that Roberts flatly refused.

[23] Solomon then traveled to California and approached Marsh with the same idea, stating that if they could produce the design within 30 days, he would put it on the cover of the magazine.

[24]Felsenstein initially wanted to build a terminal following the model of his earlier Tom Swift design, using discrete electronics.

Marsh had a woodworker friend build a large light table and Felsenstein and the layout artist began using it to design the printed circuit board for the motherboard.

He demanded from the start that it use walnut sides; while working on the digital clock project he had learned from his woodworker friend that they could get parts for practically nothing if they were small enough to be made from off-cuts.

"[27] As the machine increasingly expanded in power, Felsenstein suggested the name "Sol", because they were including "the wisdom of Solomon" in the system.

While there, Felsenstein had time to discover the problem was a tiny bit of broken wire that got stuck under a chip, shorting out two of the video lines.

Finally the Sol-20 added a keyboard with numeric keypad, and a larger power supply to feed the five expansion slots and a fan to cool them, for $995 as a kit or $1,495 assembled.

Processor Technology invited all of their dealers to a meeting in Emeryville, California, outside Berkeley, to introduce their Helios floppy disk drive for $1,199, along with their PTDOS system to work with it.

[32] To add to their woes, Processor Technology had contracted North Star Computers to write a new version of the BASIC for the Sol machines.

A patch that allowed CP/M to run on the new drives killed off any interest in alternatives like PTDOS, and new business applications like WordStar and Electric Pencil soon cemented CP/M as the standard operating system for all S-100 machines.

Meanwhile, the company introduced one of its few new products during this period, 32 and 64 kB memory cards based on dynamic RAM which was much denser than the older SRAMs.

[38] Looking at the Sol-20 from the front, where the operator would sit, the keyboard was in a typical location with the main QWERTY-style layout on the left and the numeric keypad on the right.

[27] The Sol solved this problem by supporting only one of the two data busses at a time, allowing input or output and switching between them by signaling with the DBIN pin on the 8080.

By this time the decision to use the additional lines for grounds had been made, which had the desirable side-effect of making the board easier to design.

[41] The BPB retained the DBIN signaling and ground pins of the early design and this quickly became a de facto standard for S-100 cards.

[42] CONSOL provided a simple terminal emulator function, along with a small number of additional commands to load and run programs from tape using TLOAD.

This was able to run in even a minimal machine with a 4 KB expansion, but in order to fit it had only single-precision floating point numbers and lacked string variables.

Processor Technology also sold a wide variety of other programs, including many games, on cassette format for the Sol, or on punch tape for other S-100 machines.