The IBM 709 Data Processing System was a large, general purpose digital computer designed to solve complex problems in areas of commercial and scientific interest. Large volume and extremely rapid input-output operation were major features of this system. The 709 was highly flexible and could be expanded by the addition of storage and input-output units. This system operated at high speed and offered maximum flexibility with a minimum of programming effort.

## Associated equipment

- IBM 709 Central Processing Unit for coordination of all 709 activity.

- IBM 711 Card Reader for input of punched card information.

- IBM 716 Printer for output of printed reports.

- IBM 721 Card Punch for output of punched cards.

- IBM 729 Magnetic Tape Unit and IBM 755 Tape Control for high speed storage and tape powering control.

- IBM 733 Magnetic Drum Storage for large capacity storage.

- IBM 737 Magnetic Core Storage for primary storage media.

- IBM 738 Magnetic Core Storage for large capacity storage.

- IBM 740 CRT Recorder and IBM 780 CRT Display for filmed recording and display of information.

- IBM 766 Data Synchronizer for control of multiple input-output units.

## The IBM 709 Central Processing Unit

The IBM 709 CPU served as a control for the 709 Data Processing System. This component synchronized and coordinated all 709 activity and directed problems to their solutions. The CPU incorporated an Operator's Panel which provided manual intervention to begin, interrupt or end stored program control.

- Interpreted and executed all instructions at high speed.

- Performed both fixed and floating-point arithmetic operations.

- Fixed point operations executed at a rate of 42,000 per second.

- Made comparisons, arrived at logical conclusions, and acted accordingly.

- Routed all results to the proper storage location or to an output
unit.

- Three index registers provided automatic counting and address
modification.

- Input from magnetic tape and punched cards.

- Output to magnetic tape, punched cards, printed reports, film
or visual display unit.

- Magnetic drum provided auxiliary storage capacity.

- Operator's panel permitted complete communication between system and operator.

## General information

**Operating features**

- Adaptable to both commercial and scientific applications

- Independent input-output control

- New tape unit with two-gap head for checking while writing

- Variable length input and output records

- Large capacity magnetic core storage

- Special instructions for number system conversion, e.g., binary
to decimal, decimal to binary

- Automatic indexing facilities

- Full array of logical operations

- Automatic floating point arithmetic operation

- Special instruction for facilitating compiling and interpreting

- Indirect addressing

- Facilities for real-time operations

- Variable length multiplication and division

- 36 internal sense indicators

**Input units**

IBM 711 Card Reader - Model 2

IBM 729 Magnetic Tape Unit - Model 1

**Output units**

IBM 721 Card Punch

IBM 729 Magnetic Tape Unit - Model 1

IBM 716 Printer

IBM 740 CRT Recorder

IBM 780 CRT Display

**Storage units**

IBM 737 and 738 Magnetic Core Storage

Capacity: 4096, 8192 or 32,768 words

IBM 733 Magnetic Drum Storage

Capacity: 8192 or 16,384 words

**Data Synchronizer**

Provides simultaneous and independent transmission of information between multiple input and output units and magnetic core memory.

## Arithmetic and control system

Word length of 36 binary digits (equivalent to over 10 decimal digits)

Single-address instructions

Trapping Mode: Allows automatic monitoring of program

## Calculating speeds

**Fixed point operations**

24 microsecond addition or subtraction - a rate of about 42,000 per second

240 microsecond multiplication or division - a rate of about 4000 per second

24 microsecond logical operation - a rate of about 42,000 per second

**Floating point operations**

84 microsecond addition or subtraction - a rate of about 12,000 per second

216 microsecond division - a rate of about 4500 per second

204 microsecond multiplication - a rate of about 5000 per second

## Components

**IBM 711 Card-Reader** - Model 2

Speed:250 cards per minute

Control panel flexibility

**IBM 729 Magnetic Tape Unit** - Model 1

Capacity: 1200 binary digits per lineal inch (equivalent to over 330 decimal digits)

Information Transfer Rate: 90,000 binary digits per second (equivalent to over 25,000 decimal digits per second)

Speed:

Reading or writing:75 inches per second

Rewinding: 400 inches per second average for 2400 foot tape

Variable length records and files

Operating Modes: Binary and Coded Decimal

Dimensions:Up to 2400 feet long ½ inch wide

**IBM 721 Card Punch**

Speed:100 cards per minute

Control panel flexibility

**IBM 716 Printer**

Speed:Up to 150 lines per minute; Up to 120 alphanumerical characters per line

Control panel flexibility

**IBM 740 CRT Recorder**

Speed:8,000 plotted points per second

Size:7-inch tube for photographic recording

**IBM 780 CRT Display**

21-inch tube for visual display

Card-to-Tape | 250 cards per minute |
---|---|

Tape-to-Card | 100 cards per minute |

Tape-to-Printer | 150 lines per minute, 120 characters per line or 500 lines per minute, 120 characters per line |

## Data Synchronizer

**Features:**

- Simultaneous operation of any combination of input and output functions and computing
- Real-time facilities

**Capacity:**

- Up to 3 units may be used
- 2 input-output channels per unit
- Maximum of 6 channels for simultaneous functions

**Punched Card input-output:**

- Up to 3 IBM 711 Card Readers
- Up to 3 IBM 721 Card Punches

**Line printed output:**

- Up to 3 IBM 716 Printers

**Magnetic Tape input-output:**

- Up to 48 IBM 729 Magnetic Tape Units

## Index Registers

**Capacity:**

- Three 15-bit registers

**Advantages:**

- Provide automatic address modification
- Reduce programming time
- Reduce length of program
- Reduce storage requirements for instructions

## Checking features

**Magnetic tape:**

- Horizontal and vertical redundancy check while reading or writing

**Line printer:**

- Echo checking for each printed number

**Card-to-Tape:**

- Tape: Horizontal and vertical redundancy check
- Card: Comparison of card information read at two stations

**Tape-to-Card:**

- Same as Card-to-Tape checking
- Can also be used to verify independently the validity of written tapes

**Arithmetic and logical unit:**

- Accumulator overflow check
- Divide check
- Floating point underflow and overflow check

## Additional features

**IBM 774 Tape Data Selector:**

- Independent storage and control unit enabling the rearrangement or direct transmission of data from a 727 Magnetic Tape Unit to any one of four output units: the 402, 403, or 407 Accounting Machine, or the 519 Document Originating Machine

**Magnetic Tape compatibility with:**

- 650 Data Processing System
- 701, 702, 704 and 705 Data Processing Systems

**704 Program compatibility:**

- Programs written for a 704 with Floating Point Trap may be run on the 709 without alteration except for changes in input-output routines

**FORTRAN (Automatic Formula Translation):**

- Advanced program for automatic translation of mathematical notation to efficient IBM 704 programs. The same logical concepts in FORTRAN may be used to construct a similar program translator for the 709

**IBM Service:**

- Executive and Programming Schools
- Applied Science Representatives in local IBM offices
- Special Representatives in specific industries
- Fully trained electronics maintenance engineers