UNIVAC 1100/2200 series

The UNIVAC 1100/2200 series is a series of compatible 36 bit computer systems initially made by Sperry Rand. The series continues to be supported today by Unisys Corporation as the ClearPath IX.

Table of contents

1 Architecture 1.1 Data Formats 1.2 Instruction format 1.3 Registers 2 UNIVAC 1100 series 3 SPERRY 2200 series 4 UNISYS 2200 series 5 External links

Architecture

Data Formats

• Fixed point either integer or fraction
  • Whole word - 36 bit (one's complement)
  • Half word - two 18 bit fields per word (unsigned or one's complement)
  • Third word - three 12 bit fields per word (unsigned)
  • Quarter word - four 9 bit fields per word (unsigned)
  • Sixth word - six 6 bit fields per word (unsigned)
• Floating point
  • Single precision - 36 bits: 1 sign bit, 8 bit characteristic, 27 bit mantisa
  • Double precision - 72 bits: 1 sign bit, 11 bit characteristic, 60 bit mantisa
• Alphanumeric
  • Fieldata - 6 bits
  • ASCII - 9 bits

Instruction format

Instructions are 36 bits long with the following fields:

f ( 6 bits) - function designator (opcode),

j ( 4 bits) - partial word designator, J-register designator, or minor function designator,

a ( 4 bits) - register (A, X, or R) designator or I/O designator,

x ( 4 bits) - index register (X) designator,

h ( 1 bit ) - index register increment designator,

i ( 1 bit ) - indirect address designator,

u (16 bits) - address or operand designator.

Address	Register	Contents
000	Unused	Unused
001	X1	Increment	Modifier
...	...	Increment	Modifier
013	X11	Increment	Modifier
014	X12/A0	Overlap (X or A)
...	...	Overlap (X or A)
017	X15/A3	Overlap (X or A)
020	A4	Accumulator
...	...	Accumulator
033	A15	Accumulator
034	A15+1	Unassigned (A)
...	...	Unassigned (A)
037	A15+4	Unassigned (A)
...	Executive	Protected Executive
101	R1	Special (R)
...	...	Special (R)
117	R15	Special (R)
...	Executive	Protected Executive
177	Executive	Protected Executive

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 octal) of the user registers.

There are 15 index registers (X1 ... X15), 16 accumulators (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).

UNIVAC 1100 series

1. UNIVAC 1107 introduced in 1962
2. UNIVAC 1108 introduced in 1964
3. UNIVAC 1106 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 1978
10. UNIVAC 1100/60 introduced in 1979
11. UNIVAC 1100/70 introduced in 1981
12. UNIVAC 1100/90 introduced in 1982

SPERRY 2200 series

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

1. SPERRY 2200/100 introduced in 1985

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

External links

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