The IBM 709 was an early computer system introduced by IBM in August 1958. It was an improved version of the IBM 704 and the second member of the IBM 700/7000 series of scientific computers. The IBM 709 added overlapped input/output, indirect addressing, and three "convert" instructions (which provided support for decimal arithmetic, leading zero suppression, and several other operations). The 709 had 32,768 words of 36-bit memory and could execute 42,000 add or subtract instructions or 5000 multiplies per second.
An optional hardware emulator executed legacy IBM 704 programs on the IBM 709. This was the first commercially available emulator prior to 1960. Registers and most 704 instructions were emulated in 709 hardware. Complex 704 instructions such as floating point trap and input-output routines were emulated in 709 software.
The 709 was built using vacuum tubes. IBM introduced a transistorized version of the 709, called the IBM 7090, in November 1959.
The FORTRAN Assembly Program was first introduced for the 709.
Read more about IBM 709: Registers, Instruction and Data Formats, I/O Channel