1.3 Registers

The 128 registers of the high speed "general register stack", map to the current data space in main storage starting at memory address zero. These registers include both user and executive copys of the A, X, R, and J registers and many special function executive registers.

The table on the right shows the addresses (in octalThe octal numeral system is the base 8 number system, and uses the digits 0 7. According to Donald Knuth's The Art of Computer Programming it was invented by King Charles XII of Sweden. Octal numerals can be made from binary numerals by grouping consecuti) of the user registers.

There are 15 index registerAn index register in a computer CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/ array operations. Index registers were first used in the British Manchester Mark I computer, in 1949.s (X1 ... X15), 16 accumulatorIn a CPU, an accumulator is a register in which intermediate results are stored. Without an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc. to main memory and read them back. Access to mains (A0 ... A15), and 15 special function user registers (R1 .. R15). The 4 J registers and 3 "staging registers" are uses of some of the special function R registers.

One interesting feature is that the last 4 index registers (X12 ... X15) and the first 4 accumulators (A0 ... A3) overlap, allowing data to be interpreted either way in these registers. This also results in 4 unassigned accumulators (A15+1 ... A15+4) that can only be accessed by their memory address (double word instructions on A15 do operate on A15+1).

2 UNIVAC 1100 series

1. UNIVAC 1107The UNIVAC 1107 was the first member of Sperry Rand's UNIVAC 1100 series of computers, introduced in October 1962. Also known as the Thin Film Computer because of its use of thin film memory for its register storage. Only 36 systems were sold. External li introduced in 1962Events January January 1 Western Samoa becomes independent from New Zealand January 3 Pope John XXIII excommunicates Fidel Castro January 4 New York City introduces a train that operates without a crew on-board January 8 Leonardo da Vinci's Mona Lisa is e
2. UNIVAC 1108The UNIVAC 1108 was the second member of Sperry Rand's UNIVAC 1100 series of computers, introduced in 1964. Integrated circuits replaced the thin film memory that the UNIVAC 1107 used for register storage. Smaller and faster cores were used for main memor introduced in 1964Events January January 1 Federation of Rhodesia and Nyasaland is dissolved. January 3 Senator Barry Goldwater announces that he will seek the Republican nomination for President. January 5 In the first meeting between leaders of the Roman Catholic and Ort
3. UNIVAC 1106The UNIVAC 1106 was the third member of Sperry Rand's UNIVAC 1100 series of computers, introduced in December 1969 and was absolutely identical to the UNIVAC 1108 in instruction set. Early versions of the UNIVAC 1106 were simply half speed UNIVAC 1108 sys introduced in 1969
4. UNIVAC 1110 introduced in 1972
5. UNIVAC 1100/10 redesignation of UNIVAC 1106 in 1975
6. UNIVAC 1100/20 redesignation of UNIVAC 1108 in 1975
7. UNIVAC 1100/40 redesignation of UNIVAC 1110 in 1975
8. UNIVAC 1100/181 introduced in 1975
9. UNIVAC 1100/80 introduced in 1977
10. UNIVAC 1100/60 introduced in 1979
11. UNIVAC 1100/70 introduced in 1981
12. UNIVAC 1100/90 introduced in 1982

3 SPERRY 2200 series

In 1983 Sperry Corporation discontinued usage of the name UNIVAC for their products.

1. SPERRY 2200/100 introduced in 1985
2. SPERRY Integrated Scientific Processor introduced in 1985

4 UNISYS 2200 series

In 1986 Sperry Corporation merges with Burroughs Corporation to become Unisys Corporation.

1. UNISYS 2200/200 introduced in 1986
2. UNISYS 2200/400 introduced in 1988
3. UNISYS 2200/600 introduced in 1989
4. UNISYS 2200/100 introduced in 1990
5. UNISYS 2200/500 introduced in 1993
6. UNISYS 2200/900 introduced in 1993
7. UNISYS 2200/3800 introduced in 1997

5 UNISYS ClearPath IX series

In 1996 Unisys Corporation introduces the ClearPath IX series.

6 External links

• UNIVAC® Memories
• A history of Univac computers and Operating Systems (PDF file)

Mainframe computers

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