【NEC】 N7795 Hard Disk Unit

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.

N7795 Magnetic Disk Unit Specifications (per HDA)
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)

N7795 Hard Disk Unit