UNIVAC 1101
Encyclopedia
Engineering Research Associates
Engineering Research Associates, commonly known as ERA, was a pioneering computer firm from the 1950s. They became famous for their numerical computers, but as the market expanded they became better known for their drum memory systems. They were eventually purchased by Remington Rand and merged...
(ERA) and built by the Remington Rand
Remington Rand
Remington Rand was an early American business machines manufacturer, best known originally as a typewriter manufacturer and in a later incarnation as the manufacturer of the UNIVAC line of mainframe computers but with antecedents in Remington Arms in the early nineteenth century. For a time, the...
corporation in the 1950s. It was the first stored program computer in the U.S. that was moved from its site of manufacture and successfully installed at a distant site. Remington Rand used the 1101's architecture as the basis for a series of machines into the 1960s.
Codebreaking
ERA was formed from a group of code-breakers working for the United States NavyUnited States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. The team had built a number of code breaking machines, similar to the more famous Colossus computer
Colossus computer
Not to be confused with the fictional computer of the same name in the movie Colossus: The Forbin Project.Colossus was the world's first electronic, digital, programmable computer. Colossus and its successors were used by British codebreakers to help read encrypted German messages during World War II...
in England, but designed to attack Japanese codes. After the war the Navy was interested in keeping the team together even though they had to formally be turned out of Navy service. The result was ERA, which formed in St. Paul, Minnesota in the hangars of a former Chase Aircraft
Chase Aircraft
The Chase Aircraft Company, founded in 1943, was an aircraft manufacturer of the United States of America, primarily constructing gliders and military transport aircraft. Lacking space for expansion, the company was purchased by Henry J. Kaiser in 1951. Plans to produce the C-123 transport for the...
shadow factory.
After the war, the team continued to build codebreaking machines, targeted at specific codes. After one of these codes changed, the team convinced the Navy that the only way to make a system that would remain useful was to build a fully programmable computer. The Navy was convinced, and in 1947 they funded development of a new system under "Task 13". The resulting machines, known as "Atlas", used drum memory
Drum memory
Drum memory is a magnetic data storage device and was an early form of computer memory widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria....
for main memory and featured a simple central processing unit
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
built for integer math. The first Atlas machines was built, moved, and installed at the Army Security Agency by December 1950. A faster version using Williams tubes and drums was delivered to the NSA
National Security Agency
The National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States Department of Defense responsible for the collection and analysis of foreign communications and foreign signals intelligence, as well as protecting U.S...
in 1953.
Commercialization
The company turned to the task of selling the systems commercially. Atlas was named after a character in the popular comic strip Barnaby., and they initially decided to name the commercial versions "Mabel". Jack Hill suggested "1101" instead; 1101 is the binary representation of the number 13. The ERA 1101 was publicly announced in December 1951. Atlas II, slightly modified became the ERA 1103, while a more heavily modified version with core memory and floating pointFloating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
math support became the UNIVAC 1103A.
At about this time the company became embroiled in a lengthy series of political maneuverings in Washington, DC. Drew Pearson's Washington Merry-Go-Round claimed that the founding of ERA was a conflict of interest for Norris and Engstrom because they had used their war-time government connections to set up a company for their own profit. The resulting legal fight left the company drained, both financially and emotionally. In 1952 they were purchased by Remington Rand, largely as a result of these problems.
Remington Rand had recently purchased Eckert-Mauchly Computer Corporation
Eckert-Mauchly Computer Corporation
The Eckert–Mauchly Computer Corporation was founded by J. Presper Eckert and John Mauchly, and was incorporated on December 22, 1947. After building the ENIAC at the University of Pennsylvania, Eckert and Mauchly formed EMCC to build new computer designs for commercial and military applications...
, builders of the famed UNIVAC I
UNIVAC I
The UNIVAC I was the first commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC...
, the first commercial computer in the US. Although ERA and UNIVAC were run separately within the company, looking to cash in on the UNIVAC's well known name, they renamed the machine to become the "UNIVAC 1101". A series of machines based on the same basic design followed, and were sold into the 1960s before being replaced by the similar-in-name-only UNIVAC 1100 family.
Description
This computer was 38 ft (11.6 m) long, 20 ft (6.1 m) wide, and used 2700 vacuum tubeVacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
s for its logic circuits. Its drum memory was 8.5 in (21.6 cm) in diameter, rotated at 3500 rpm, had 200 read-write heads, and held 16,384 24-bit words (a memory size equivalent to 48 kB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
) with access time between 32 microseconds and 17 milliseconds.
Instructions
Instruction set
An instruction set, or instruction set architecture , is the part of the computer architecture related to programming, including the native data types, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O...
were 24 bits long, with 6 bits for the opcode
Opcode
In computer science engineering, an opcode is the portion of a machine language instruction that specifies the operation to be performed. Their specification and format are laid out in the instruction set architecture of the processor in question...
, 4 bits for the "skip" value (telling how many memory locations to skip to get to the next instruction in program sequence), and 14 bits for the memory address. Numbers were binary with negative values in ones' complement. The addition time was 96 microseconds and the multiplication time was 352 microseconds.
The single 48-bit accumulator
Accumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...
was fundamentally subtractive, addition being carried out by subtracting the ones' complement of the number to be added. This may appear rather strange, but the subtractive adder reduces the chance of getting negative zero in normal operations.
The machine had 38 instructions.
Instruction Set
| Conventions | |
|---|---|
| y is memory box at address y | X = X-Register (24 digits) |
| is interpreted as the contents of | Q = Q-Register (24 digits) |
| A = Accumulator (48 digits) | |
| Arithmetic | |
| Insert (y) in A | Insert complement of (y) in A |
| Insert (y) in A [multiple precision] | Insert complement of (y) in A [multiple precision] |
| Insert absolute value (y) in A | Insert complement of absolute value (y) in A |
| Add (y) to (A) | Subtract (y) from (A) |
| Add (y) to (A) [multiple precision] | Subtract (y) from (A) [multiple precision] |
| Add absolute value of (y) to (A) | Subtract absolute value of (y) from (A) |
| Insert (Q) in A | Clear right half of A |
| Add (Q) to (A) | Transmit (A) to Q |
| Insert [(y) + 1] in A | |
| Multiply and divide | |
| Form product (Q) * (y) in A | Add logical product (Q) * (y) to (A) |
| Form logical product (Q) * (y) in A | Divide (A) by (y), (quotient forms in Q, non-negative remainder left in A) |
| Add product (Q) * (y) to (A) | |
| Logical and control flow | |
| Store right half of (A) at y | Shift (A) left |
| Store (Q) at y | Shift (Q) left |
| Replace (y) with (A) using (Q) as operator | Take (y) as next order |
| Replace (y) with (A) [address portion only] | Take (y) as next order if (A) is not zero |
| Insert (y) in Q | Take (y) as next order if (A) is negative |
| Take (y) as next order if (Q) is negative | |
| Input Output and control | |
| Print right-hand 6 digits of (y) | Optional Stop |
| Print and punch right-hand 6 digits of (y) | Intermediate Stop |
| Final Stop |
External links
- Engineering Research Associates and the Atlas Computer (UNIVAC 1101) by George Gray,
from the Unisys History Newsletter, Volume 3, Number 3, June, 1999 - Introducing the ERA 1101: An operationally proven high-speed, electronic, general purpose digital computer, ERA, no-date. (8 pp) http://ed-thelen.org/comp-hist/ERA-1101-f09-IntroductingERA1101.pdf
- Oral history interviews with ERA personnel on 1101, Charles Babbage InstituteCharles Babbage InstituteThe Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....
, University of Minnesota. Interviewees include Arnold A. Cohen; Arnold DumeyArnold DumeyArnold I. Dumey was the co-inventor of the postal sorting machine and cryptanalyst first for SIS and then NSA. During WWII he worked for the Army Signal Corps and at Arlington Hall, headquarters of the US Army's Signal Intelligence Service cryptography, under William and Elizabeth Friedman on...
http://www.cbi.umn.edu/oh/display.phtml?id=48; John Lindsay Hill; Frank C. Mullaney; and William C. Norris http://www.cbi.umn.edu/oh/display.phtml?id=67. - ERA 1101 Documents list of 44 scanned course notes on 1101 by H. C. Snyder USN
- Summary of Characteristics Magnetic Drum Binary Computer, Engineering Research Associates Pub No. 25, 30 November 1948