Encyclopedia > IBM 709

  Article Content

IBM 709

The IBM 709 an improved version of the IBM 704, introduced by IBM in August, 1958 was the second member of the IBM 700/7000 series. The IBM 709 added overlapped input/output, indirect addressing[?], and decimal instructions.

Instruction Format

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 registers[?], 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.

All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
Ocean Beach, New York

... 0.00% from two or more races. 2.17% of the population are Hispanic or Latino of any race. There are 61 households out of which 29.5% have children under the age of 18 ...

This page was created in 22.1 ms