IBM 37xx explained
IBM 37xx (or 37x5) is a family of IBM Systems Network Architecture (SNA) programmable communications controllers used mainly in mainframe environments.
All members of the family ran one of three IBM-supplied programs.
- Emulation Program (EP) mimicked the operation of the older IBM 270x non-programmable controllers.
- Network Control Program (NCP) supported Systems Network Architecture devices.
- Partitioned Emulation Program (PEP) combined the functions of the two.
Models
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.[1] It supported up to 32 lines.[2]
371x
The 3710 communications controller was introduced in 1984.[3]
372x series
The 3725 and the 3720 systems were announced in 1983. The 3725 replaced the hardware line scanners used on previous 370x machines with multiple microcoded processors.
- The 3725 was a large-scale node and front end processor.
- The 3720 was a smaller version of the 3725,[4] which was sometimes used as a remote concentrator.
- The 3726 was an expansion unit for the 3725.
With the expansion unit, the 3725 could support up to 256 lines at data rates up to 256 kbit/s, and connect to up to eight mainframe channels.
Marketing of the 372x machines was discontinued in 1989.[5]
IBM discontinued support for the 3705, 3720, 3725 in 1999.
374x series
- The 3745, announced in 1988,[6] 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.[7] A stand-alone model 950 appeared in 1995.[8]
Successors
IBM no longer manufactures 37xx processors. The last models, the 3745/46, were withdrawn from marketing in 2002.[9] Replacement software products are Communications Controller for Linux on System z and Enterprise Extender.
Clones
Several companies produced clones of 37xx controllers, including NCR COMTEN and Amdahl Corporation.[10]
Notes and References
- Book: Pugh, Emerson. IBM's 360 and Early 370 Systems. 1991. MIT press. 0-262-16123-0. registration.
- Book: IBM Corporation. IBM 3704 and 3705 Communications Controllers Hardware: Student Text. 1979. 2012-09-01. 2011-03-22. https://web.archive.org/web/20110322170327/http://www.bitsavers.org/pdf/ibm/370x/SR20-4544-2_IBM_3704_and_3705_Communications_Controller_Hardware.pdf. dead.
- News: Edwards. M.. Communications Processors Rise to Challenge of Larger, Faster Networks.. September 8, 2012. Communications News. April 1, 1985.
- News: Horwitt. Elizabeth. IBM Unveils low-end SNA connectivity. September 1, 2012. Computerworld. May 26, 1986.
- News: Guptill. Bruce. FEPs provide variations on networking theme. September 2, 2012. Network World. May 29, 1989.
- News: Brown. Bob. Low-end FEP market to expand through early 90s. September 2, 2012. Network World. April 25, 1988.
- News: Cooney. Michael. IBM adds rich array of network products. September 2, 2012. Network World. Sep 21, 1992.
- News: Guruge. Anura. IBM's Nways: much ado about nothing. September 2, 2012. Network World. July 24, 1995.
- Book: White, Bill. IBM Communication Controller for Linux on System z V1.2.1 Implementation Guide. 2006. IBM Corporation. 0-738-49665-0. 2. etal.
- News: Korzeniowski. Paul. Data dialog ditties. September 7, 2012. Network World. December 15, 1986.
