IBM 700/7000 series

Early problems with OS/360 and the high cost of converting software kept many 7000s in service for years afterward.

However, its architecture is not compatible with those of the 7000 and 1400 series, so some 360 models have optional features that allow them to emulate the 1400 and 7000 instruction sets in microcode.

They are relatively slow and it was common for 7000 series installations to include an IBM 1401, with its much faster peripherals, to do card-to-tape and tape-to-line-printer operations off-line.

Some of the technology for the 7030 was used in data channels and peripheral devices on other 7000 series computers, e.g., 7340 Hypertape.

To expand the memory from 2048 to 4096 words, a 33rd instruction was added that uses the most-significant bit of its address field to select the bank.

Processor registers consisted of: 2,048 or 4,096 – 36-bit binary words with six-bit characters IBM's 36-bit scientific architecture was used for a variety of computation-intensive applications.

The ultimate model was the Direct Coupled System (DCS) consisting of a 7094 linked to a 7044 that handled input and output operations.

The decrement field often contains an immediate operand to modify the results of the operation, or is used to further define the instruction type.

Because the unit record equipment on the 709x was so slow, punched card I/O and high-speed printing were often performed by transferring magnetic tapes to and from an off-line IBM 1401.

Later, the data channels were used to connect a 7090 to a 7040 or a 7094 to a 7044 to form the IBM 7094/7044 Direct Coupled System (DCS).

Its pseudo-operation BSS, used to reserve memory, is the origin of the common name of the "BSS section", still used in many assembly languages today for designating reserved memory address ranges of the type not having to be saved in the executable image.

The 700/7000 commercial architecture inspired the very successful IBM 1400 series of mid-sized business computers.

Fifteen five-character fields in fixed locations in low memory can be treated as index registers, whose values can be added to the address specified in an instruction.

All of the 700 and 7000 series machines predate standard performance measurement tools such as the Whetstone (1972), Dhrystone (1984), LINPACK (1979), or Livermore loops (1986) benchmarks.

IBM 701 operator's console
An IBM 704 installation
IBM 7090's at NASA's Project Mercury, 1962
Logic module from a 700 series IBM computer featuring 5965 vacuum tubes
Transistorized IBM Standard Modular System (SMS) card used in the 7000 series
IBM 702
IBM 7080
IBM 7010 system: console (in front), disc drives and processing modules (left), tape storage, punch card reader and printer (right)
IBM 7074