# IBM 2790

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/IBM_2790
> Markdown URL: https://mediated.wiki/source/IBM_2790.md
> Source: https://en.wikipedia.org/wiki/IBM_2790
> Source revision: 1339062283
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

The **IBM 2790 Data Communications System** is a family of devices intended for "in-plant data communications and production monitoring."[1] It is described as a two-way data communications system designed to accommodate large volumes of short messages from many in-plant locations or from smaller groups of terminals at remote locations.[2]

The 2790 consists of one IBM 2715 Transmission Control Unit, or an [IBM 1800 Data Acquisition and Control System](/source/IBM_1800_Data_Acquisition_and_Control_System),[3] which controls the other system components. The 2715 supports up to 32 KB of [magnetic core memory](/source/Magnetic-core_memory) with a 1.2 μs cycle time, an internal disk for [microcode](/source/Microcode) load, a 2740 printer/keyboard, and a real time clock.[4] The 2715 provides terminal control, transaction assembly, data-entry checking, message routing, transaction storage, and transfer of data to and from a [IBM System/370](/source/IBM_System/370), IBM 1800, or an [IBM System/7](/source/IBM_System/7).

- 2715 Model 1: Used for local operation
- 2715 Model 2: Used for remote attachment with a binary synchronous communication adapter such as a [270x](/source/270x) communications controller.

The 2715 supports a mix of other devices, all connected by a two-wire loop operating at 500 kbit/s.[4] There are numerous data entry devices that can be attached:

- The IBM 2791 Area Station is a tabletop unit attached to the 2790 loop. The 2791 can read ten column identification badges and eighty column punched cards, and has a twelve key pad for direct entry of numeric data. The 2791 can attach up to thirty-two 2795/2796 data entry units, a 1053 printer, up to three 1035 remote badge readers, and an OEM device. The 2791 has nine user defined "transaction buttons". Up to 100 2791/2793 can be attached.
- The IBM 2793 Area Station is similar, but lacks the ability to accept input data directly. It can attach up to thirty-two data entry units and a 1053 printer. Up to 100 2791/2793 can be attached.
- The IBM 2795, 2796 and 2797 Data Entry Units are compact industrial units for reporting job and machine status and production information.[1] Both have two ten-position switches and a ten column badge reader. The 2796 has an additional two switches and allows for manual entry of up to four digits.
- 2740 Communications Terminal (one)
- 2798 Guided Display Units. This is a versatile and compact data entry and output unit with a 56 character keyboard, 8 control keys and 16 position visual display. Up to 12 can be attached.

## References

1. IBM Corporation. [*Customer Engineering Announcement: The IBM 2790 Data Communication System*](http://ed-thelen.org/comp-hist/IBM-ProdAnn/2790.pdf)

1. [*IBM System/370 System Summary*](http://www.bitsavers.org/pdf/ibm/370/systemSummary/GA22-7001-6_370_System_Summary_Dec76.pdf). IBM. 1976. pp. 8–26.

1. [*Systems Reference Library IBM 2790 Data Communication System Component Description*](https://bitsavers.org/pdf/ibm/2790/A27-3015-0_IBM_2790_Data_Communication_System_Comp_Desc_196907.pdf). IBM Corporation. July 1969. p. 5. Retrieved November 17, 2025.

1. Hippert, R. O. (November 1970). ["IBM 2790 Digital Transmission Loop"](https://ieeexplore.ieee.org/document/5391596). *IBM Journal of Research and Development*. **14** (6): 662–667. [doi:10.1147/rd.146.0662](https://doi.org/10.1147/rd.146.0662). [ISSN 0018-8646](https://www.worldcat.org/issn/0018-8646)

---
Adapted from the Wikipedia article [IBM 2790](https://en.wikipedia.org/wiki/IBM_2790) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/IBM_2790?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.