IBM 705

The IBM 700/7000 series is a series of large-scale (mainframe) computer systems that were made by IBM through the 1950s and early 1960s. The series includes several different, incompatible processor architectures. The 700s use vacuum tube logic and were made obsolete by the introduction of the transistorized 7000s. The 7000s, in turn, were eventually replaced by System/360, which was announced in 1964. However the 360/65, the first 360 powerful enough to replace 7000s, did not become available until November 1965. Early problems with OS/360 and the high cost of converting software kept many 7000s in service for years afterward.

The IBM 700/7000 series has six completely different ways of storing data and instructions:

The 700 class use vacuum tubes, the 7000 class is transistorized. All machines (like most other computers of the time) use magnetic core memory; except for early 701 and 702 models, which use CRT memory.

Early computers were sold without software. As operating systems began to emerge, having four different mainframe architectures plus the 1400 midline architectures became a major problem for IBM since it meant at least four different programming efforts were required.

The System/360 combined the best features of the 7000 and 1400 series architectures into a single design. However, some 360 models have optional features that allow them to emulate the 1400 and 7000 instruction sets in microcode. One of the selling points of the System/370, introduced in mid-1970, was improved 1400/7000 series emulation, which could be done under operating system control rather than shutting down and restarting in emulation mode as was required on the 360s.

While the architectures differ, the machines in the same class share electronics technologies and generally use the same peripherals. Tape drives use 7-track format, with the IBM 727 for vacuum tube machines and the 729 for transistor machines. Both the vacuum tube and most transistor models use the same card readers, card punches and line printers that were introduced with the 701. These units, the IBM 711, 721 and 716, are based on IBM accounting machine technology and even include plugboard control panels. 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. Three later machines, the 7010, the 7040 and the 7044, adopted peripherals from the midline IBM 1400 series. Some of the technology for the 7030 was used in data channels and peripheral devices on other 7000 series computers, e.g., 7340 Hypertape.

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