This was a processor group of large general-purpose machines, and was comprised of four models: the M-660D, M-660H, M-660K and M-662K.
The M-660H was a large machine, positioned as the successor of the M-260H, and the processor was miniaturized with fewer gates by using an efficient logic system. At the same time, 1 megabit DRAM was installed for the first time in a domestic machine in order to reduce the machine cycle to the greatest extent possible. Using logic systems for greater speed, such as look-ahead control and a high-speed decimal operation mechanism, these processors achieved world-class high-performance and space/power-savings.
The M-660K was the higher-end model of the M-660H. It could also be field upgraded to the M-662K.
The M-662K was a dyadic processor with two instruction processors. It was the top-end model among M-66X processors, and its performance was about 3.5 times better than the M-660D.
The M-660D was the entry model for the M-66X Processor Group. It could be field upgraded to higher-end models.
Hitachi also produced the M-660 Processor Group E Models, which were enhanced versions of these machines.
| M-660D | M-660H | M-660K | M-662K | |
|---|---|---|---|---|
| Number of instruction processors | 1 | 2 | ||
| Buffer memory capacity | 32KB | 64KB | 64KBx2 | |
| Main memory capacity | 32-256MB | 64-256MB | ||
| Number of channels | 8-32 | 16-32 | ||
| Announcement date | March 1987 | August 1986 | March 1987 | |
