# IBM System/360 Model 195

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The **IBM System/360 Model 195** is a discontinued IBM computer introduced on August 20, 1969. The Model 195 was a reimplementation of the [IBM System/360 Model 91](/source/IBM_System/360_Model_91) design using [monolithic integrated circuits](/source/Monolithic_integrated_circuit).[1] It offers "an internal processing speed about twice as fast as the [Model 85](/source/IBM_System/360_Model_85), the next most powerful System/360".[2] The Model 195 was discontinued on February 9, 1977, the same date as the System/370 Model 195.

About 20 Model 195 systems were produced.[3][4]

## Technical specifications

The basic CPU cycle time is 54 nanoseconds (ns). The system has a high degree of [parallelism](/source/Parallelism_(computing)) and can process up to seven operations at a time. The system can be configured with 1, 2, or 4 MB of [magnetic core memory](/source/Magnetic_core_memory) (models 195J, 195K, and 195L) with a cycle time of 756 ns. A 32 KB [cache](/source/CPU_cache), called a *buffer memory* in the IBM announcement, is standard. Memory blocks are brought into cache in units of 64 bytes.[2]

The normal operating system for the Model 195 is [OS/360 Multiprogramming with a Variable Number of Tasks (MVT)](/source/OS/360_and_successors#MVT).

## Components

The 360/195 has the following components:[5]

- 2160 Model l System Console
- 2180 CPU Power Unit[a]
- 2185 Power Distribution Unit
- 2186 Coolant Distribution Unit
- 2195 Processing Unit (which includes the Processor Storage)
- 2860 Selector Channel[b]
- 2870 Multiplexer Channel[b]
- 2880 Block Multiplexer Channel[b]

## Legacy

The Model 195 was later updated as the [IBM System/370 Model 195](/source/IBM_System/370_Model_195) with the new [System/370](/source/IBM_System/370) instructions and the 370 time-of-day clock and control registers, but without the [virtual memory](/source/Virtual_memory) hardware.[6]

## Notes

1. Model depends on configuration.

1. Optional, but there must be at least one channel.

## References

1. gah (April 20, 2008). ["The 360/91 and associated machines"](https://groups.yahoo.com/neo/groups/hercules-390/conversations/messages/53873)

1. ["IBM Archive: System/360 Model 195"](https://web.archive.org/web/20230729090329/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2195.html). *IBM*. 23 January 2003. Archived from [the original](https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2195.html) on 2023-07-29. Retrieved June 28, 2017.

1. Mark Smotherman. ["Eager Execution / Dual Path / Multiple Path"](https://people.computing.clemson.edu/~mark/eager.html) 15 Model 91's and 2 Model 95's were built. Approximately twenty Model 195's were built.

1. Michael J. Flynn (December 2, 1997). ["Some Reflections on Computer Engineering: 30 Years after the IBM System 360 Model 91"](https://web.archive.org/web/20161221084029/https://pdfs.semanticscholar.org/ceea/f56b486b7290c8638d3781e53de3229efda7.pdf). *Semantic Scholar*. [S2CID 5958256](https://api.semanticscholar.org/CorpusID:5958256). Archived from [the original](https://pdfs.semanticscholar.org/ceea/f56b486b7290c8638d3781e53de3229efda7.pdf) on December 21, 2016. About twenty Model 91s were made, and perhaps an equivalent number of the Model 195.

1. ["System Components"](http://bitsavers.org/pdf/ibm/360/functional_characteristics/GA22-6943-1_360-195_Functional_Characteristics_197008.pdf). *IBM System/360 Model 195 - Functional Characteristics*. Systems Reference Library. First ed. August 1969. pp. 6–8. A22-6943-O. Retrieved April 16, 2025.

1. ["IBM 360/370/3090/390 Model Numbers"](http://www.beagle-ears.com/lars/engineer/comphist/model360.htm)

## External links

- [IBM System/360 Model 195 Functional Characteristics](http://bitsavers.org/pdf/ibm/360/functional_characteristics/GA22-6943-1_360-195_Functional_Characteristics_197008.pdf)

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Adapted from the Wikipedia article [IBM System/360 Model 195](https://en.wikipedia.org/wiki/IBM_System%2F360_Model_195) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/IBM_System%2F360_Model_195?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.