IBM 37xx

• Emulation Program mimicked the operation of the older IBM 270x non-programmable controllers.
• Network Control Program supported Systems Network Architecture devices.
• Partitioned Emulation Program combined the functions of the two.

  370x series

• 3705 — the oldest of the family, introduced in 1972 to replace the non programmable IBM 270x family. The 3705 could control up to 352 communications lines.
• 3704 was a smaller version, introduced in 1973. It supported up to 32 lines.

  371x

372x series

• The 3725 was a large-scale node and front end processor.
• The 3720 was a smaller version of the 3725, which was sometimes used as a remote concentrator.
• The 3726 was an expansion unit for the 3725.

374x series

• The 3745, announced in 1988, provides up to eight T1 circuits. At the time of the announcement IBM was estimated to have nearly 85% of the over US$825 million market for communications controllers over rivals such as NCR Comten and Amdahl Corporation. The 3745 is no longer marketed, but still supported and used.
• The 3746 "Nways Controller" model 900, unveiled in 1992, was an expansion unit for the 3745 supporting additional token ring and ESCON connections. A stand-alone model 950 appeared in 1995.

  Successors

Clones