【Hitachi】 HITAC M-68X Processor Group

This was a processor group of ultra-large general-purpose machines, comprised of 4 models (the M-680H, M-682H, M-683H and M-684H) plus the M-680D entry model.

At the time, the M-680H was in the world's top class in terms of speed, being 2--2.5 times faster than the previous M-280H in business processing, and 2--3 times faster than the previous M-280H in scientific and engineering calculations. By developing semiconductors with ultra-high integration, as well as the latest mounting technology and logic system technology, Hitachi realized a true "all LSI machine". Ultra high-speed processing was made possible by more sophisticated pipeline control, high-speed arithmetic mechanisms, high-speed decimal operation capability, high-speed buffer memory, and a 3-level memory configuration which provided high-capacity working memory. This was the only air-cooled system among competing machines in the same class.

The M-682H was a dyadic processor with two instruction processors, and had processing capacity about 1.7--1.9 times that of the M-680H.

The M-683H was comprised of three instruction processors. It could also operate with high availability due to the duplication of key processor mechanisms.

The M-684H was comprised of four instruction processors. Key processor mechanisms were duplicated, just as in the M-683H.

Hitachi also produced the M-680 Processor Group E Models, which were enhanced versions of these machines.

M-68X Processor Group Configuration Specifications
  M-680D M-680H M-682H M-683H M-684H
Number of instruction processors 1 2 3 4
Buffer memory capacity 128KB 256KB 256KBx2 256KBx3 256KBx4
Main memory capacity 32-512MB 64-512MB 128-512MB
Number of channels 16-64 32-64 48-128 64-128
Announcement date May 1986 March 1985 May 1986

HITAC M-680HHITAC M-684HHighly integrated package used for HITAC M-68X