7090 Data Processing System

The following are excerpts from the December 30, 1958 7090 product announcement package.

The 7090 is a transistorized data processing system which is functionally the same as the 709. It is a high speed system which contains all the features of the 709. Some of the new features are:

1. Computes five times faster than IBM 709 system.
2. Eight input/output data channels.
3. High speed magnetic tape units.
4. Intermixing of IBM 729-II and 729-IV Magnetic Tape Units.
5. Automatic priority processing using data channel trap.
6. Separate operator's console for centralized control.
7. New transistor circuits provide speed and reliability.
8. New high speed core storage.
9. New packaging for better space utilization.
10. Costs less to install and operate than IBM 709 system.

Compatibility with other IBM systems has been vigorously maintained in the design of the IBM 7090. Retraining and reprogramming costs are minimized because of:

1. Direct program compatibility with the IBM 709 system.
2. Compatibility feature for IBM 704 programs.
3. Input/output compatibility with all IBM Data Processing Systems.

Because the IBM 7090 is a direct improvement of the IBM 709, the customer will continue to benefit from the following features:

1. Efficiency of parallel binary logic.
2. Built-in floating point arithmetic.
3. No-lost-time indexing.
4. Computing simultaneous with multiple input/output operations under automatic control.
5. Convert instructions enable efficient execution of commercial applications.
6. Designed for use with real-time input/output.
7. Indirect addressing, including data channel commands.
8. Full word of sense indicators.

*Data Channels and Input/Output units may be added as desired.

Function: The 7100 Central Processing Unit contains the arithmetic and stored program control circuits for the 7090 system.

Operation: Computation is in the very efficient binary arithmetic, and as with most internal operations, is accomplished in parallel in a 36-bit fixed word length. Instructions are provided to simplify the conversion for decimal or other coded input-output.

More than 200 different operational instructions are provided. They include: fixed-point arithmetic operations, floating-point arithmetic operations, logical operations on information in registers and storage, control and testing operations, input-output operations, shifting operations, and numerous indexing operations. Also provided are instructions for number system conversion and automatic table look-up operations, instruction for facilitating compiling and interpreting, variable length multiplication and division, thirty-six internal sense indicators to provide program flexibility, indirect addressing to facilitate program writing of sub-routines, and automatic floating-point overflow-underflow trap. In addition, control for independent data transmission is provided, permitting concurrent data transmission and computation without logical interference with the computer.

Arithmetic section: This section of the central processing unit consists of a storage register, an accumulator register, and a multiplier-quotient register, each with a capacity of 35 bits and sign; and a 36-bit sense indicator register. The accumulator register has, in addition, two overflow positions. The accumulator and multiplier-quotient registers are coupled when multiplying or dividing to store a 70-bit product or dividend and may also be coupled together to shift information left or right.

Index registers: Three index registers provide automatic indexing facilities, and make possible automatic address modification and loop control within programs. All three index registers have 15 positions.

Automatic priority processing: The data channel trap feature gives the programmer a valuable tool with which to control input-output operation. The data channel is allowed to signal the central processing unit upon completion of an input-output operation or an error condition. The program may then provide for further input-output operation without complex timing conditions or proceed to a corrective action.

Speed: Typical execution times for instructions (including storage reference) are: fixed point; Add — 4.8 microseconds, multiply — 4.8 to 48 microseconds (depending on the number of consecutive zeros in multiplier), divide — 48 microseconds. Floating point; Add — 16.8 microseconds, multiply — 16.8 to 40.8 microseconds (depending on the number of consecutive zeros in the multiplier), divide — 43.2 microseconds. Most logical operations take 4.8 microseconds.

• Five times faster computing than the IBM 709 -- All arithmetic and logical execution times for the IBM 7090 system are one-fifth the execution times listed for the IBM 709 system.
  
  
• Eight input/output data channels -- The IBM 7606 Multiplexor is capable of handling a maximum of eight IBM 7607 Data Channels. Each Data Channel may have a total of ten IBM 729-II or 729-IV Magnetic Tape Units attached to it. Each will also handle one IBM 711 Card Reader, one IBM 721 Card Punch, and one IBM 716 Printer. A maximum IBM 7090 system would therefore include 80 magnetic tape units, 8 card readers, 8 card punches, and 8 printers.
  
  
• High speed magnetic tape units -- Up to eight IBM 729-IV Magnetic Tape Units can be operated simultaneously, moving a maximum of 3 million bits a second. Each character is automatically checked by the two-gap head and dual level sensing.
  
  
• Intermixing Of IBM 729-II AND 729-IV Magnetic Tape Units --The IBM 7607 Data Channel, a new unit, combines the data handling and tape control function of the IBM 755 Tape Control and one channel of the IBM 766 Data Synchronizer. It is capable of handling up to ten intermixed IBM 729-II and 729-IV Magnetic Tape Units. No addressing restrictions apply to the intermixed tape units on a given data channel.
  
  
• Automatic priority processing using data channel trap -- The data channel trap gives the programmer a valuable tool with which to control input/output operation. By means of this feature, the Data Channel signals the main program upon completion of an input/output operation or error condition. The program may then provide for initiation of further input/output operation without considering complex timing restrictions.
  
  
• Separate operator's console for centralized control -- The IBM 7151 Console Control Unit contains the switching, indicators, and register displays now present on the IBM 709 console plus additional data channel indicators. The console can be conveniently located for the best centralized control of the system.
  
  
• New transistor circuits for speed and reliability -- The IBM Drift Transistors, which have been developed specifically for use in high speed computers, are the active components in our new standard Current Switching circuits. These circuits are designed to remain operative despite aging of the components, thus insuring the utmost in reliability will be gained from our solid state components.
  
  
• New high speed core storage -- The IBM 7302 Magnetic Core Storage has a capacity of 32,768 thirty-six bit words; the access time for extracting or storing a word does not exceed 2.4 microseconds, including the complete read and rewrite cycle. The speed of this memory is made possible because of the development of new materials and the manufacture of much smaller cores than are used in the IBM 709.
  
  
• New packaging for best possible space utilization -- The IBM 7090 is packaged in standard modules, specifically designed for accessibility and ease of maintenance. Each unit contains two vertical pull-out drawers, each of which has two "pages" that are hinged in a vertical plane. In the closed position the wiring side of the page is exposed, permitting ready access to all test points. In the open position the pluggable printed wiring transistor cards may be easily removed and replaced. As a result of this IBM standardization program and the compact packaging of the circuitry, the modular units may be placed side by side and thus minimize space requirements. As much as 50 percent of floor space may be saved when compared with IBM 709 requirements.
  
  
• More economical to install and operate than IBM 709 -- Through transistorization, outstanding reductions in power and air conditioning will be realized by IBM 7090 users. An IBM 7090 may save as much as 70 percent of the power requirements of an IBM 709.

• Direct program compatibility with the IBM 709 system --The IBM 7090 has been designed to permit the programmer the widest ease and flexibility in the manipulation of data. As in the IBM 709, over two hundred instructions are built into the IBM 7090. Except for instructions referring to the IBM 733 Magnetic Drum Storage and the IBM 740 CRT Recorder, all IBM 709 instructions will be included in the IBM 7090. Therefore, comparable IBM 7090 and IBM 709 systems will have complete program compatibility, and up to five times the speed of the IBM 709.
  
  
• Compatibility feature for IBM 704 programs -- Like the IBM 709, the IBM 7090 will include the compatibility feature. This feature used with an interpretive program (the memory capacity of the IBM 7090 must be twice that required by the 704 for the program) to enable most programs written for the IBM 704 to run on the IBM 7090. Thus, many of the 704 programs which have consumed many man years of training and experienced programmer time, may be run on the 7090 until superseded.
  
  
• Input/Output compatibility with all IBM systems -- In addition to direct input/output compatibility with the IBM 704 and 709, punched cards and magnetic tape records prepared by any other IBM data processing system may be used as input to an IBM 7090. In turn, the IBM 7090 may prepare punched card and magnetic tape records, which may be used as input to any other IBM data processing system.
  
  
• FORTRAN -- an automatic coding system for aid in programming scientific problems has been prepared for many IBM systems, including the IBM 7090. This program greatly reduces the coding burden by having the machine prepare its own program from combined algebraic and logical statements of the problem solution procedure. FORTRAN, a compiler of over 30,000 instructions, accepts these statements and produces an efficient object program in machine language. Approximately ten machine instructions are produced, on the average, for each statement written by the programmer.

The 7151 is a separate unit which provides centralized control of the 7090 system. The 7151 contains indicators, switches, keys and register displays. Channel indicators are provided and the register displays have been grouped for the operator's convenience. Information in any storage location or register can be displayed and/or changed by manual insertion through the entry keys and switches.

The 7302 contains 32,768 words of high speed magnetic core storage. Random access to any of the 36-bit words requires only 2.4 microseconds. This includes the time to execute a complete read and rewrite cycle. All 32,768 storage locations are directly addressable.

The 7606 accomplishes all data switching necessary to store data in core storage. Data channels and the central processing unit transmit all data to and from core storage through the multiplexor. The 7606 provides the only means of access to core storage. A maximum of eight 7607 Data Channels may be attached to the 7606. Only one 7606 is used with a 7090 system.

The 7607 contains the control circuits, registers and counters to provide simultaneous and independent transfer of information between input-output units and core storage via the 7606 Multiplexor. At least one 7607 Model 1 must be attached to the 7090 Data Processing System. A maximum of eight data channels may be attached. Each channel contains a 36-bit shift register and a 36 position data register that transfers data to or from core storage via the multiplexor in a 36-bit parallel operation.

The 7608 is used to convert the incoming power of 60 cycle alternating current to 400 cycle alternating current. This provides well regulated output power to the system.