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 System/360 Model 91
SuccessorSystem/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. 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 Model 91" (PDF). 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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