In July 1990, NEC announced the N7795 high-capacity hard disk unit together with the ACOS System 3800.
This unit was an extension of the N7768 hard disk unit, which employed a 9-inch plated disk and was shipped in 1989 while large hard disk units were switching from 14-inch to 9-inch disks. It achieved greater compactness, higher density and greater capacity, and higher data transfer speed by using a thin-film magnetic head, thin-film (plated) magnetic disk media, improved servo circuits, the 1-7 RLL modulation code, and other improvements.
As a product, NEC also offered a model which had half the memory capacity because the cylinders accessed were limited to half the area, but speed was increased by reducing average seek time from 12msec to 10msec.
| Memory capacity(GB) | 2.85 |
|---|---|
| Average seek time(msec) | 12 |
| Average rotational delay(msec) | 8.1 |
| Data transfer speed(MB/sec) | 4.5 |
| Disk diameter(inch) | 9 |
| Number of disks | 9 |
| Number of heads(information recording part) | 15 |
| Number of cylinders (figure in parentheses is for alternates) | 2742+(4) |
| Recording density(bpi) | 37800 |
| Track density(tpi) | 1670 |
| Recording system | 1-7RLL |
| Total memory capacity(GB)(entire unit) | 22.8 |
| Unit dimensions(mm) (entire unit) | 825(W)×780(D)×1790(H) |
