Scsi/Data-Compression Chip; Overview; Features - Seagate STD124000N Product Manual

Chapter 7

SCSI/Data-Compression Chip

Overview

Features

Page 68
The Seagate SCSI/data-compression chip contains compression and
decompression circuitry, which forms the core of the data-compression system
using the DCLZ algorithm. This core is called the DCLZ compression machine .
The DCLZ machine compresses data from the SCSI bus before it is transferred to
the local control bus. When compressing information, data originates from the SCSI
bus and passes through the SCSI core to the DCLZ machine or data-compression
core. However, that interface performs byte operations in the event of an odd block
size.
The Seagate SCSI/data-compression chip used in the Scorpion 24 tape drive
provides the basis for an effective data-compression system using the DCLZ
algorithm. The chip includes a SCSI controller and a data-compression processor
arranged in an inline configuration.
Like other component devices used in these state-of-the-art drives, the SCSI/data
compression chip uses the low-power CMOS technology. The device is packaged in
a 100-pin plastic quad flat pack (PQFP).
The SCSI/data-compression device provides the following features:
z
Integrated SCSI controller
z
Implements DCLZ data-compression algorithm
z
Provides 10.0 Mbyte-per-second maximum throughput for synchronous
operation and 7.0 Mbytes per second for asynchronous operation
z
Compatible with DDS compression standards
z
Provides internal data FIFO
z
Supports data pass-through mode to bypass compression
z
Provides internal SCSI data FIFO
z
Built-in DMA control unit
Data Compression
DAT Drives