IBM System/360 Model 195

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 design using monolithic integrated circuits.[1] It offers "an internal processing speed about twice as fast as the 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.

IBM System/360 Model 195
DeveloperIBM
Release dateAugust 20, 1969
Introductory price$7–12.5 million
DiscontinuedFebruary 9, 1977
PredecessorIBM S/360 Model 91
SuccessorIBM S/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 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 (models 195J, 195K, and 195L) with a cycle time of 756 ns. A 32 KB 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).

Legacy

The Model 195 was later updated as the IBM System/370 Model 195 with the new System/370 instructions and the 370 TOD clock and control registers, but without the virtual memory hardware.[5]

References
  1. gah (April 20, 2008). "The 360/91 and associated machines". hercules-390@yahoogroups.com (Mailing list).
  2. "System/360 Model 195". IBM Archive. IBM. 23 January 2003. Retrieved June 28, 2017.
  3. Mark Smotherman. "Eager Execution / Dual Path / Multiple Path". 15 Model 91's and 2 Model 95's were built. Approximately twenty Model 195's were built.
  4. Michael J. Flynn (December 2, 1997). "Some Reflections on Computer Engineering: 30 Years after the IBM System 360 Model 91" (PDF). Semantic Scholar. S2CID 5958256. Archived from the original (PDF) on December 21, 2016. About twenty Model 91s were made, and perhaps an equivalent number of the Model 195.
  5. "IBM 360/370/3090/390 Model Numbers".
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