Browse Prior Art Database

Low-Cost Interconnection of SCSI Devices

IP.com Disclosure Number: IPCOM000115635D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 108K

Publishing Venue

IBM

Related People

Cutts, SJ: AUTHOR [+6]

Abstract

A product permitting ready expansion of storage capacity in a low cost computing system typically uses a 19-inch rack-mounted drawer to contain disk drives, for example 16-bit differential SCSI devices. The mechanical design is generally subject to design constraints, requiring, for example, drives to be arranged in two groups of eight, in mechanical sub-structures called "eight-packs", each eight-pack having "side-cheeks" though which all signal and power connections are routed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Low-Cost Interconnection of SCSI Devices

      A product permitting ready expansion of storage capacity in a
low cost computing system typically uses a 19-inch rack-mounted
drawer to contain disk drives, for example 16-bit differential SCSI
devices.  The mechanical design is generally subject to design
constraints, requiring, for example, drives to be arranged in two
groups of eight, in mechanical sub-structures called "eight-packs",
each eight-pack having "side-cheeks" though which all signal and
power connections are routed.

      Interconnection of 16-bit differential SCSI devices in a
limited space presents a problem.  Industry standard sixty-eight way
high-density (50 thousand pitch) SCSI connectors are very expensive
when the cost is multiplied by eight.  A customer might well want to
begin with just one or two drives and purchase further drives for an
upgrade, making it essential to minimise the cost of the eight-pack
assembly.

      It is also desirable to provide a redundant power path at
minimum cost.

      The solution described here (Fig. 1) uses eight male connectors
each of which has a three times thirty-two pin configuration.  This
permits a large cable-mounted female connector (two times thirty way)
to be plugged onto the male connectors, leaving free a one times
thirty-two column of pins for power and other miscellaneous non-SCSI
signals.

      The sixty most critical SCSI signals are routed through a two
times thirty wire "twist-and-flat" internal bus, dropping two (NC)
No-Connect signals and one of the seven grounds.  The remaining two
signals (TERMPWR & DIFFSNS) are routed through a power/miscellaneous
cable loom (Figs. 2 and 3).

      A PCB in each side-cheek "scrambles" the sixty-eight way bus
into a sixty-way bus.  Each of the drives is mounted in a carrier
assembly which docks onto the male connectors in the eight-pack.  The
carrier contains a small "stub...