The Autonetics RECOMP II was a

computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

first introduced in 1958. It was made by the

Autonetics Autonetics was a division of North American Aviation that produced various avionics but is best known for their inertial navigation systems used in submarines and intercontinental ballistic missiles. Its 188-acre facility in Anaheim, California, w ...

division of

North American Aviation North American Aviation (NAA) was a major American aerospace manufacturer that designed and built several notable aircraft and spacecraft. Its products included: the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F ...

. It was attached to a desk that housed the input/output devices. Its desk integration made it a hands-on small system intended for the scientific and engineering computing market. The computer weighed about , including input-output.

Architecture

It had a

40-bit 4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. In mathematics Four is the smallest c ...

word size, 20-bit instruction size. Memory and registers were on a fixed head disk that operated like a

drum memory Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. For many early computers, drum memory formed the main working memory ...

—4080 words on standard tracks, 16 words on

fast loop track Fast or FAST may refer to: * Fast (noun), high speed or velocity * Fast (noun, verb), to practice fasting, abstaining from food and/or water for a certain period of time Acronyms and coded Computing and software * ''Faceted Application of Subje ...

s, registers A, B, R, X each on their own high-speed loop track, and one prerecorded read only clock track.Autonetics Recomp Theory of Operation
/ref> It had a complete set of built-in

floating point operation In computing, floating point operations per second (FLOPS, flops or flop/s) is a measure of computer performance, useful in fields of scientific computations that require floating-point calculations. For such cases, it is a more accurate mea ...

s, including

square root In mathematics, a square root of a number is a number such that ; in other words, a number whose ''square'' (the result of multiplying the number by itself, or  ⋅ ) is . For example, 4 and −4 are square roots of 16, because . E ...

. Floating-point values used two words, one for the exponent and one for the fraction for a total of 80 bits. Whereas the full 40-bit word was used for data, instructions were only 20 bits long and were stored two per word. Since indexing was commonly done by modifying the address part of an instruction (say, by adding one to access the next data item in a list), such instructions always had to be in the second half-word, and the first half-word was padded with a NOP instruction. Programmers also used these NOP instructions to provide space for future inserted instructions, since the assembler did not allow for use of symbolic addresses, and the insertion of a single instruction could otherwise require rewriting a lot of code. The machine had a

bit-serial architecture In digital logic applications, bit-serial architectures send data one bit at a time, along a single wire, in contrast to bit-parallel word architectures, in which data values are sent all bits or a word at once along a group of wires. All dig ...

Punched paper tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...

was the external storage medium. The desk also had an electronic typewriter for printed output and a keyboard integrated with the system console to allow typed input and system control. Programs written in machine code could be input to the system from the console.

References

External links

Autonetics RECOMP II documents
On Bitsavers.org Early computers Computer-related introductions in 1958

Architecture

References

Further reading

External links