Viatron

Viatron Computer Systems, or simply Viatron was an American computer company headquartered in Bedford, Massachusetts, and later Burlington, Massachusetts. Viatron coined the term "microprocessor" although it was not used in the sense in which the word microprocessor is used today.
Viatron was founded in 1967 by engineers from Mitre Corporation led by Dr. Edward M. Bennett and Dr. Joseph Spiegel. In 1968 the company announced its "System 21" small computer system together with its intention to lease the systems starting at a revolutionary price of $40 per month. The basic system included a microprocessor with 512 characters of read/write RAM memory, a keyboard, a CRT display and two cartridge tape drives.
The system specifications, advanced for 1968 – five years before the advent of the first commercial personal computers – caused a lot of excitement in the computer industry. The System 21 was aimed, among others, at applications such as mathematical and statistical analysis, business data processing, data entry and media conversion, and educational/classroom use.
The expectation was that the use of new large scale integrated circuit technology (LSI) and volume would enable Viatron to be successful at lower margins, however the prototype did not incorporate LSI technology. In 1968 Bennett claimed that by 1972 Viatron would have delivered more "digital machines" than had "previously been installed by all computer makers." He declared "We want to turn out computers like GM turns out Chevvies,"
The semiconductor industry was unable to produce circuits in the volumes required, forcing Viatron to sell fewer than the planned 5,000–6,000 systems per month. This raised the production costs per unit and prevented the company from ever achieving profitability.
Bennet and Spiegel were fired in 1970, and the company declared Chapter XI bankruptcy in 1971.
System 21 components.
As announced the System 21 line consisted of the following:
CPU.
The Viatron CPUs differed in memory size and interrupt levels – 2 on the 2140 and 4 on the 2150. They had the ability to operate on 8-bit, 16-bit, 32-bit, or 48-bit data. Three index registers were provided.
The CPUs included two independent arithmetic units with different capabilities.
The system had two instruction formats: "Standard", 16-bit instructions, and "Extended", 32-bit instructions. Standard instructions had a 6-bit operation code, a two-bit index register identifier, and an 8-bit PC-relative address. Extended instructions had a 6-bit operation code, a two-bit index register identifier, an 8-bit operation code modifier, and a 16-bit memory address. Indirect addressing was allowed.
There were 85 instructions, some of which had both standard and extended forms: