Jump to content

IBM 7070

From Alfawiki
IBM 7070
Company typeProduct / Computer
IndustryComputing / Data processing
PredecessorIBM 650, IBM 705
Founded1958
SuccessorIBM 7080, IBM System/360
ProductsDecimal-based transistorized stored-program computer
ParentIBM

IBM 7070 represents a decimal-based intermediate data processing machine launched by IBM in 1958. As a member of the IBM 700/7000 series, it marked IBM's initial venture into transistorized stored-program computer technology, succeeding the earlier vacuum tube models.

Designed to replace both the IBM 650 and IBM 705, the 7070 was not backward compatible with the 650 instruction set, necessitating a simulator to execute legacy software. Additionally, it did not serve as a seamless upgrade for the 705 due to incompatibilities such as partial character set support. Consequently, IBM released the transistorized IBM 7080, which offered full compatibility shortly thereafter.

Data storage utilized words composed of 10 decimal digits plus a sign, encoded via a two-out-of-five coding scheme. Memory configurations included either 5,000 or 9,990 words of core storage, with an operational speed near 27KIPS. Leasing fees were approximately $17,400 monthly, while outright purchase cost about $813,000. The system's physical weight was roughly .

The product line expanded with the introduction of the faster IBM 7074 in 1960, accommodating up to 30,000 words of memory, and the budget-friendly IBM 7072 in 1961, which employed slower tape drives. These variants were ultimately replaced by the System/360, unveiled in 1964.

Architecture

The IBM 7070 is word-addressable and many instructions specify ranges of digits. It utilizes a unified address space encompassing both registers and core memory, featuring three accumulators and 99 index words. Digits are numbered by IBM starting at zero for the most significant digit.

Instructions generally consist of a signed two-digit operation code, two-digit fields for indexing and control, and a four-digit address. The control field frequently defines instruction parameters.

Record Definition Words (RDWs) are employed for:

  1. Block data transfer
  2. Input/Output operations
  3. Table lookups

A minus sign designates the final RDW within a list; alpha signs are invalid in this context. Each RDW identifies the start and end addresses of a data block.

Hardware implementation

The logic and control sections of the 7070 use complemented transistor diode logic (CTDL), while timing and core storage circuits employ current-mode logic. These components are built from Standard Modular System (SMS) cards. The system comprises around 30,000 alloy-junction germanium transistors and approximately 22,000 germanium diodes spread over about 14,000 SMS cards.

Input/Output in original announcement

The IBM 7070 series—including models 7070, 7072, and 7074—supports several peripherals: one IBM 7150 console typewriter; up to four IBM 7300 disk storage units interfaced through IBM 7604 Tape Control and IBM 7605 RAMAC Control; as many as forty IBM 729 tape drives connected via IBM 7604 Tape Control (the slower IBM 7330 tape drives are used on the 7072); and six unit-record devices (three input and three output) linked through an IBM 7603 Input/Output Synchronizer along with IBM 7600 Input/Output control.

Mode of operation

Input/output processes rely on lists composed of RDWs, with the concluding RDW marked by a minus sign. Each RDW specifies block start and end addresses.

Each I/O channel (up to four in total) can connect as many as ten IBM 729 tape drives; the first two channels also support four IBM 7300 disk drives. These channels function asynchronously relative to the processor and generate priority interrupts upon operation completion.

Unit-record devices interface via the IBM 7600 Input/Output control unit through a 7603 synchronizer that buffers cards and print lines. Completion of data transfer between device and buffer triggers priority interrupts; however, transfers between buffer and core storage halt processor activity until finished, with a maximum transfer size of sixteen words.

The IBM 7150 console typewriter and the IBM 7501 console card reader connect directly to the IBM 7600 Input/Output control unit.

729 Tape Drives

The IBM 729 is a seven-track tape drive employed in the majority of IBM 14xx and 70xx computer models. It was offered in models II and IV, which operate at a recording density of 556 BPI but also support 200 BPI to maintain compatibility with earlier versions. Subsequent models V and VI increased the recording density to 800 BPI. This tape drive was not utilized with the 7072 system.

7150 Console Control Unit

The 7150 includes a console typewriter that serves as the primary interface for system control and facilitates communication with active programs through the 7600 I/O control mechanism.

7151 Console Card Reader

The 7151 is a specialized version of a keypunch, designed solely for reading punched cards.

7300 Disk Storage Units

The IBM 7300 Disk Storage Unit provides storage capacity of six million digits and was superseded by the IBM 1301 in 1961.

7330 Tape Drive

The IBM 7330 offers a cost-effective, slower alternative to the IBM 729, supporting dual densities of 200 BPI and 556 BPI. This model was not compatible with the 7070 or 7074 computers.

7400 Printer

Up to three 7400 Printers can be connected to the 7603 Input/Output Synchronizer. These printers produce output on 120-column lines at speeds reaching 150 lines per minute, with print formatting controlled by a wired plugboard.

7500 Card Reader

As many as three 7500 Card Readers may attach to the 7603 Input/Output Synchronizer, capable of reading standard 80-column punched cards at rates up to 500 cards per minute. The layout is managed by a plugboard.

7550 Card Punch

Up to three 7550 Card Punches can be connected to the same synchronizer, punching data onto 80-column cards at speeds up to 250 cards per minute, also utilizing a wired plugboard for layout control.

7907 Data Channel

The 7907 is an 8-bit data channel that shares interface compatibility with the 7908 and 7909 channels found on the IBM 7080 and IBM 7090 systems.

1301 and 1302 Disk Storage

Introduced in 1961, the IBM 1301-1 Disk Storage Unit offered a storage capacity of 28 million characters per module and replaced the IBM 7300. It interfaces through an IBM 7907 Data Channel via an IBM 7631-II File Control unit. The later-announced IBM 1302 in 1963 expanded this capacity fourfold compared to the original model.

7340 Hypertape

The IBM 7340 Hypertape, launched in 1961, connects through an IBM 7907 Data Channel using an IBM 7640 Hypertape Control unit.

1414 I/O Synchronizer

The IBM 1414-6 Input-Output Synchronizer includes six buffer units and supports multiple serial input/output devices such as:

  • The 1009 Data Transmission Unit (modem)
  • The 1011 Paper Tape Reader
  • The 1014 Remote Enquiry Units (keyboards and typewriters)
  • Telegraph input/output devices

This synchronizer connects to the 7070/7074 systems via the IBM 7907 Data Channel Switch, which executes channel programs stored in main memory.

See also

  • IBM 608, IBM's first fully transistorized product featuring plugboard programmability

External links

Retrieved from "https://www.alfawiki.org/index.php?title=IBM_7070&oldid=27969"