The IBM 2365 Processor Storage is a
magnetic-core memory
Magnetic-core memory was the predominant form of random access, random-access computer memory for 20 years between about 1955 and 1975.
Such memory is often just called core memory, or, informally, core.
Core memory uses toroids (rings) of a ...
storage unit that is a component of the
IBM System/360
The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applica ...
models
65,
,
and
85 computers, which were released between 1965 and 1968.
Storage is implemented using magnetic cores with a storage width of 72
bits, which comprise 64 data bits (8
bytes, or one doubleword) plus 8 parity bits. The IBM 2365 model 1 contains 131,072 (128 K) bytes of memory; all other models contain 262,144 (256 K) bytes. The model 2 could be converted in the field to a model 13.
All models other than the model 1 consist of two memory stacks. Addressing for the stacks is
interleaved, so the first 64-bit word is in one stack, the second in the other stack, and so forth. This improves performance when doing sequential access.
All models other than the model 5 have a cycle time of 750
nanoseconds.
Models
The various models are used as follows:
* Model 1 is used on the System/360 model 65 when not used as a multiprocessor.
* Model 2 is used on the System/360 models 65 (when not used as a multiprocessor) and 67-1.
* Model 3 is used on the System/360 model 75.
* Model 5 is used on the System/360 model 85.
* Model 12 is used on the System/360 model 67-2.
* Model 13 is used on the System/360 model 65 when used as a multiprocessor.
Use with the System/360 model 85
The IBM 2365 model 5 is special because the System/360 model 85 accesses memory in
128-bit
While there are currently no mainstream general-purpose processors built to operate on 128-bit ''integers'' or addresses, a number of processors do have specialized ways to operate on 128-bit chunks of data.
Representation
128-bit processors co ...
(16 byte) units, unlike the other System/360 models which support the IBM 2365, all of which access
64-bit
In computer architecture, 64-bit Integer (computer science), integers, memory addresses, or other Data (computing), data units are those that are 64 bits wide. Also, 64-bit central processing unit, CPUs and arithmetic logic unit, ALUs are those ...
(8 byte) units. On the System/360 model 85, the IBM 2365 model 5 operates with a cycle time of 1040 nanoseconds, and two or four of them are required. Because the System/360 model 85 CPU is so much faster than memory, if there are two IBM 2365 model 5 components they are two-way interleaved, and if there are four IBM 2365 model 5 components they are four-way interleaved. Because the IBM 2365 model 5 is internally two-way
interleaved, sequential 128-bit memory operations issued by the System/360 model 85 CPU traverse all the memory components before cycling back to the first.
The IBM 2365 model 5 is used only with the System/360 model 85 with 524,288 (512 K) or 1,048,576 bytes (1 MB) of storage.
IBM 2385 Processor Storage
The
IBM System/360 Model 85
The IBM System/360 Model 85 is a high-end member of the System/360 family of computers, with many advanced features, and was announced in January 1968 and first shipped in December 1969. IBM built only about 30 360/85 systems because of "a reces ...
, when configured with 2,097,152 (2 MB, 360/85 K85) or 4,194,304 (4 MB, 360/85 L85) bytes, uses the IBM 2385 instead of the IBM 2365 Processor Storage. The IBM 2385 has a cycle time of 960
nanoseconds compared to 1,040 nanoseconds for the IBM 2365 model 5.
References
External links
IBM System/360 model 85 product announcement
{{DEFAULTSORT:Ibm 2365 Processor Storage
Computer memory
2365