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The IBM 7090 was a second-generation Transistorized version of the earlier IBM 709 vacuum tube Mainframe Computer s and was designed for "large-scale scientific and technological applications". The 7090 was the third member of the IBM 700/7000 Series scientific computers. The first 7090 installation was in November 1959 . In 1960, a typical system sold for $2,900,000 or could be rented for $63,500 a month. The 7090 used a 36-bit Word Length , with an address-space of 32K (32,768) words. It operated with a basic memory cycle of 2.18 μs, using the IBM 7302 Core Storage Core Memory technology from the IBM 7030 (Stretch) project. IBM 7094 AND IBM 7040/7044 An upgraded version, the IBM 7094, was first installed in September 1962 . It had seven index registers, instead of three on the earlier machines. The 7094 console had a distinctive box on top that displayed lights for the four new index registers. The 7094 introduced double-precision floating point and additional instructions, but was largely Backward Compatible with the 7090. Minor changes in instruction formats, particularly the way the additional index registers were addressed, sometimes caused problems. In 1963 , IBM introduced lower cost machines with a similar architecture, but fewer instructions and simplified I/O, called the IBM 7040 and '''7044.''' In April 1964 , the first '''7094 II''' was installed, which had almost twice as much general speed as the 7090 due to a faster clock cycle and introduction of overlapped instruction execution. INSTRUCTION AND DATA FORMATS The basic instruction format was a 3-bit ''prefix'', 15-bit ''decrement'', 3-bit ''tag'', and 15-bit ''address''. The prefix field specified the class of instruction. The decrement field often contained an immediate operand to modify the results of the operation, or was used to further define the instruction type. The three bits of the tag specified three '' Index Register s'' (seven in the 7094), the contents of which were ''subtracted'' from the address to produce an ''effective address''. The address field either contained an address or an immediate operand.
Octal notation was used in documentation and programming. INPUT/OUTPUT The 7090 series featured a data channel architecture for input and output, a forerunner of modern Direct Memory Access I/O. Up to 10 data channels could be attached. The datachannels had their own instruction set. These were used with tape and later disk storage and offered high performance for the time. Printing and Punch Card I/O, however, employed modified Unit Record Equipment and was slow. It became common to use a less expensive IBM 1401 computer to read cards onto Magnetic Tape for transfer to the 7090/94. Output would be '' Spool ed'' onto tape and transferred to the 1401 for printing or card punching using its much faster peripherals, notably the IBM 1403 line printer. Later IBM introduced the 7094/7044 Direct Coupled System, using data channel to data channel communication, with the 7094 primarily performing computations and the 7044 performing I/O operations. NOTABLE APPLICATIONS
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