IBM 2780/3780

The IBM 2780[1] and the IBM 3780[2] are devices developed by IBM to perform remote job entry (RJE) functions. They communicate with the mainframe via Binary Synchronous Communications (BSC or Bisync).

2780

The 2780, first shipped in 1967,[3] comes in four models. The Model 1 can read punched cards and transmit the data to a remote host computer, and can receive and print data sent by the host. The Model 2 adds the ability to punch card data received from the host, The Model 3 can only print data received from the host, but not send data to it. The model 4 can read and punch card data, but has no printing capabilities.

The 2780 uses a dedicated communication line at speeds of 1200, 2000, 2400 or 4800 bits per second. It is a half duplex device, although full duplex lines can be used with some increase in throughput. It can communicate in Transcode (a 6-bit code), 8-bit EBCDIC, or 7-bit ASCII.

The card reader/punch unit, similar to an IBM 1442, can read up to 400 cards per minute (cpm) and can punch up to 355 cpm. The 2780 line printer is similar to the IBM 1443[4] and can print up to 240 lines per minute (lpm), or 300 lpm using an extremely restricted character set. The 2780 is also capable of local (offline) card to print operation.

3780

The IBM 3780, an enhanced version of the 2780, was announced in May 1972.[5] The 3780 was developed by IBM's Data Processing Division (DPD).[6]

The 3780 drops Transcode support and incorporates several performance enhancements. It supports compression of blank fields in data using run-length encoding. It provides the ability to interleave data between devices, introduces double buffering, and adds support for the Wait-before-transmit ACKnowledgement (WACK) and Temporary Text Delay (TTD) Binary Synchronous control characters.[7]

The 3780 can read cards at 600 cards per minute and punch cards at 160 columns per second. The printer is rated at 400 lines per minute.[8]

These devices were later emulated on various types of equipment, including eventually the personal computer. A notable early emulation was the DN60, by Digital Equipment Corporation in the late 1970s.[9]

2770, 3770

A similar device, the 2770, announced in 1969, "was said to surpass all other IBM terminals in the variety of available input-output devices."[10] The 2770 can attach the 2213 Printer, the 2502 Card Reader, the 545 Card Punch, the 2265 Display Station, the 1017 Paper Tape Reader, the 1018 Paper Tape Punch, the 50 Magnetic Data Inscriber, and the 1255 Magnetic Character Reader. The printer and devices for any two other media can be attached to one 2772 Control Unit.[11] The 2770 was developed by the IBM General Products Division (GPD) in Rochester, MN.[12] An SNA successor, the 3770, a Data Processing Division (DPD) product, appeared in 1974.[13]

Notes
  1. picture of an IBM 2780
  2. picture of an IBM 3780
  3. IBM Corporation. "Rochester chronology". Retrieved June 3, 2012.
  4. IBM 1443 printer description
  5. "IBM Archives: DPD chronology, page 4". IBM. Retrieved 2007-01-18.
  6. "IBM Archives: DPD Chronology". Retrieved June 24, 2012.
  7. Hewlett Packard. "RJE/XL Node Manager's Guide". Retrieved June 7, 2012.
  8. IBM Corporation (1979). IBM Sales Manual: DP Machines (PDF).
  9. Maintenance manual for the DN60 series, includes an overview of BISYNC
  10. Pugh; et al. (1991). IBM's 360 and Early 370 Systems. The MIT Press. ISBN 0-262-16123-0.
  11. IBM Corporation. IBM Field Engineering Announcement: The IBM 2770 Data Communication System (PDF).
  12. "IBM Archives: Rochester Chronology". Retrieved June 24, 2012.
  13. Frank, Ronald A. (June 25, 1975). "IBM 3770 Performance, Savings, Please Service Firm". Computerworld. Retrieved June 23, 2012.
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References
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