Difference between revisions of "PDP-11/74"
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| − | The '''PDP-11/74''' was | + | The '''PDP-11/74''' was an experimental (it never went into production) tightly-coupled symmetric [[multi-processor]] version of the [[PDP-11/70]] from [[Digital Equipment Corporation|DEC]]; it could hold from two to four [[Central Processing Unit|CPUs]]. |
It used a [[multi-port memory]] version of the [[MK11 memory system]], the MKA11. Some [[peripheral|devices]], such as [[disk]]s and [[magnetic tape drive]]s, could be shared between two of the CPUs, using the multi-port capabilities of many [[MASSBUS]] devices; other devices (e.g. [[UNIBUS]] devices) could not be shared (other than via [[software]], or use of a [[UNIBUS switch]]). | It used a [[multi-port memory]] version of the [[MK11 memory system]], the MKA11. Some [[peripheral|devices]], such as [[disk]]s and [[magnetic tape drive]]s, could be shared between two of the CPUs, using the multi-port capabilities of many [[MASSBUS]] devices; other devices (e.g. [[UNIBUS]] devices) could not be shared (other than via [[software]], or use of a [[UNIBUS switch]]). | ||
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There was also a planned [[Commercial Instruction Set]] processor, the CISP. | There was also a planned [[Commercial Instruction Set]] processor, the CISP. | ||
| − | A significant run of prototypes were produced, and the [[RSX-11]] [[operating system]] was enhanced to support multi-processor operation. The -11/74 was cancelled, however (reputedly | + | A significant run of prototypes were produced, and the [[RSX-11]] [[operating system]] was enhanced to support multi-processor operation. The -11/74 was cancelled, however (reputedly the concern as that with its very high [[input/output|I/O]] bandwidth, it would compete with the new [[VAX-11/780]], but this appears to be a canard; concern about its commercial viability was apparently the cause), and never appeared as a product. |
{{semi-stub}} | {{semi-stub}} | ||
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| + | ==External links== | ||
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| + | * [https://www.miim.com/faq/hardware/multipro.shtml PDP-11 Multiprocessor FAQ] | ||
{{PDP-11}} | {{PDP-11}} | ||
[[Category: UNIBUS PDP-11s]] | [[Category: UNIBUS PDP-11s]] | ||
Revision as of 18:25, 21 August 2021
The PDP-11/74 was an experimental (it never went into production) tightly-coupled symmetric multi-processor version of the PDP-11/70 from DEC; it could hold from two to four CPUs.
It used a multi-port memory version of the MK11 memory system, the MKA11. Some devices, such as disks and magnetic tape drives, could be shared between two of the CPUs, using the multi-port capabilities of many MASSBUS devices; other devices (e.g. UNIBUS devices) could not be shared (other than via software, or use of a UNIBUS switch).
The CPU was the KB11-E CPU, a modified version of the KB11-C CPU of the -11/70. An Interprocessor Interrupt (IIST) facility in each CPU, interconnected over a private bus, allowed one CPU to interrupt or bootstrap another CPU. A multi-ported high-resolution 'Time of Day' clock was also provided. Also, the ASRB instruction implementation was modified to be atomic, for use in synchronization between CPUs.
There was also a planned Commercial Instruction Set processor, the CISP.
A significant run of prototypes were produced, and the RSX-11 operating system was enhanced to support multi-processor operation. The -11/74 was cancelled, however (reputedly the concern as that with its very high I/O bandwidth, it would compete with the new VAX-11/780, but this appears to be a canard; concern about its commercial viability was apparently the cause), and never appeared as a product.
External links
