Introducing Sol Systems - A complete computer/terminal concept This advert - which was part of an impressive six-page spread - shows the Sol-20, a machine which first shipped only a month before in December 1976, as well as the impressive range of peripherals which were available for it. It was designed by Lee Felsenstein and was essentially a way of building a computer around Felsenstein's earlier Video Display Module - the VDM-1, which had been introduced at the Albuquerque Altair Convention in March 1976 - which was the first ever memory-mapped alphanumeric display for personal computers[source: https://www.computerhistory.org/timeline/computers/]. The Sol-20 was an S-100-based system which offered a range of CPU options - the Intel 8080, 8080A or 9080A - together with 1024 "words" of static RAM and the same again of PROM, out of a total maximum of 64K. It also came with three interchangeable "Personality Modules", which were plug-in ROM chips. The socket for these was on the motherboard, but it was accessible from the rear of the machine, making them easy to change. The first - and default - module was called SOLOS, and was tailored to hobbyist users as it provided a built-in machine-code monitor, as well as access to cassette-tape routines and I/O. Because it was in ROM it was instantly available when the machine booted. The other modules were known as SOLED, which turned the Sol-20 into an "advanced editing terminal system", and CONSOL, which was the cheapest of the three but which provided minimal capability to the machine[source: Owner's Report: The Sol-20 Computer, Ken Wheeler, PCW, July 1978, p. 40]. Processor Technology started out in 1975 manufacturing memory modules and other I/O boards for machines like MITS Altair, which shared the same S-100 bus architecture - known originally as the Altair bus. It also manufactured the first S-100 video display, which the Sol-20 shipped with as standard - this was still fairly unusual for computers at the time as video output was mostly an optional extra, even for systems like the Apple 1. It was also possible to buy the Sol in "Sol PC" form, which was basically just the motherboard, for $475, or about [[320|1977]] in [[now]] money. The full system, according to a price list on sol20.org, retailed for $5450 (about [[3650|1977]] in [[now]] money) - this included BASIC 5 on floppy, the disk drive to load it, a display monitor, and two entirely separate 16K memory modules. About 10,000 Sol-20s were apparently made, but the company didn't adapt to the third generation of computers and went bust in 1979[source: http://en.wikipedia.org/wiki/Processor_Technology]. An article in PCW titled "Save our Sol" alludes to this as UK-based S-100 bus specialist Cromart had started manufacturing Processor Technology's video display monitor, having bought the rights after the company failed[source: "Save our Sol", PCW, October 1979, p. 34]. The Sol-20 also came without a resident interpreter - you had to load BASIC from tape or floppy every time you booted the machine up. The third-generation machines that would appear in a few months' time - the Commodore PET, Apple II and TRS-80 - would differ from this approach not least because their BASICs were stored in ROM and so were ready to go when the machine was turned on. This became the default for the next five or six years before the IBM PC put everything a step backwards by reverting to the "boot then load something extra to do useful stuff afterwards" convention.