Viatron

Viatron Computer Systems Corporation

Company type	Private
Industry	Computer manufacturing
Founded	1967
Founder	Dr. Edward M. Bennett, Dr. Joseph Spiegel
Defunct	1971
Fate	Filed for Chapter XI bankruptcy protection
Headquarters	Bedford, Massachusetts; later Burlington, Massachusetts , United States
Products	System 21 compact computer, System 21 Terminal, System 21 computers (2140 and 2150)

Viatron Computer Systems Corporation, commonly known as Viatron, was a U.S.-based computer manufacturer initially located in Bedford, Massachusetts before relocating to Burlington, Massachusetts. The company is credited with originating the term "microprocessor," albeit not as it is understood today.

Established in 1967 by a group of engineers from Mitre Corporation under the leadership of Dr. Edward M. Bennett and Dr. Joseph Spiegel, Viatron unveiled its System 21 compact computer in 1968. The firm intended to offer these systems on a lease basis at an unprecedented rate of $40 per month. The fundamental configuration consisted of a microprocessor with 512 characters of read/write memory, a keyboard, a 9-inch CRT display, and a pair of cartridge tape drives.

The System 21 boasted advanced features for its time—five years prior to the debut of commercial personal computers—drawing considerable attention within the industry. Its primary applications targeted fields such as mathematical and statistical computations, business data processing, data entry tasks, media format conversion, and educational purposes.

Viatron anticipated leveraging emerging large scale integrated circuit (LSI) technology alongside high production volumes to achieve profitability despite thin margins; however, the prototype did not incorporate LSI components. In 1968, Bennett forecasted that by 1972 Viatron would surpass all previous manufacturers in digital machine deliveries combined, famously stating, "We want to turn out computers like GM turns out Chevvies."

Unfortunately, semiconductor suppliers failed to produce components at the required scale, resulting in sales figures that fell well short of the targeted 5,000–6,000 units per month. This shortfall drove up per-unit manufacturing costs and hindered financial viability.

In 1970, both Bennett and Spiegel were removed from their positions, and by 1971 Viatron filed for Chapter XI bankruptcy protection.

System 21 components

The System 21 series comprised several essential elements:

• System 21 Terminal: An early example of an intelligent terminal equipped with either the 2101 or 2111 microprocessors. It featured a CRT display capable of presenting four lines of 20 characters with optional color support, a keyboard, control panel, and compatibility with up to two peripheral devices:
  • Processors:
    • 2101 – included 512 sixteen-bit words of ROM and 400 eight-bit character magnetic-core read/write memory.
    • 2111 – offered 1024 sixteen-bit words of ROM alongside 400 eight-bit character magnetic-core read/write memory.
  • Peripherals:
    • Printing robot – an attachment mounted on an IBM Selectric typewriter that produced typed output at a speed of 12 characters per second.
    • Card Reader-punch – connected to an IBM 129 keypunch machine enabling punched card input and output.
    • Communications adapter – facilitated serial ASCII communication at a rate of 1200 bits per second.
    • Tape channel attachments – supported up to two "Viatape" cartridge tape drives capable of reading and writing 80-character records at 1200 bps; also compatible with IBM-format magnetic tape mini-reels.
    • Foreign device attachment – provided parallel input/output using ASCII or Hollerith punch-card encoding.

• System 21 computers: Two variants were launched—the 2140 and the 2150—both utilizing MOS LSI central processing units along with magnetic core memory featuring a 2 microsecond cycle time and sixteen-bit word length. Each unit weighed approximately .
  • The 2140 model contained 4 KW of memory and could support up to eight local or remote System 21 terminals.
  • The 2150 model was equipped with 8 KW of memory and allowed connection to as many as twenty-four terminals.
  • Software supplied with these systems included the Viatron Programming System (VPS), which comprised:
    • DDL-I (Distributed Data Language I)
    • An assembler
    • A subroutine library covering I/O operations, mathematical functions, arithmetic procedures, and data conversion routines
    • Utility programs such as loaders, dumpers, and library managers
    • A FORTRAN IV compiler provided as standard on the 2150 model

Together, these elements illustrated Viatron’s holistic strategy to offer cost-effective computing solutions by integrating intelligent terminals with expandable computer hardware and comprehensive software packages.

CPU

Viatron's central processing units differed in memory capacity and interrupt capabilities—featuring 2 levels on the 2140 model and 4 on the 2150—and supported data widths of 8, 16, 32, or 48 bits, equipped with three index registers.

Each CPU incorporated two separate arithmetic units:

• Arithmetic Unit I included three 16-bit registers labeled A, B, and C, along with a 16-bit buffer register designated as D.
• Arithmetic Unit II managed both arithmetic and addressing functions through four registers: the program counter (P), two specialized registers (R and E), and Q, which was utilized for 32-bit operations (paired with A as the high-order bits) or 48-bit calculations (combined with A and B). Additionally, Q served as the multiplier-quotient register during multiplication and division processes.

Instruction formats comprised a 16-bit Standard type and a 32-bit Extended type. The Standard format included a 6-bit opcode, a 2-bit identifier for the index register, and an 8-bit address relative to the program counter. The Extended format expanded this by adding an 8-bit opcode modifier along with a full 16-bit memory address. Support for indirect addressing was also provided.

The instruction set contained a total of 85 commands encompassing:

• Arithmetic operations such as addition, subtraction, multiplication, and division
• Logical functions including AND, OR, and exclusive OR
• Load and store instructions
• Shift and rotate operations
• Memory alteration commands and conditional skip instructions
• Input/output handling
• Branching instructions (both conditional and unconditional), including those that save the program counter
• Register-specific operations like incrementing, decrementing, complementing, negating, and moving data—primarily targeting registers A, B, and C. Additional commands included wait states and no-operation instructions.

Typeface

In 1971, Viatron engaged Harry N. Peble to develop the patented Viafont-X typeface, engineered to ensure readability by both humans and machines, effectively supporting its optical character recognition systems.