Product manual

Theory of operations 35
Theory of operations
Overview
The Scorpion 40 tape drive design integrates DAT technology (helical scan recording
method) into a true computer-grade data-storage peripheral with industry-standard
data-compression capability.
These drive designs are the result of:
• Combining the economies of scale for key components, such as the cylinder,
heads and audio LSIs, with a computer grade drive (3.5-inch) using four direct
drive motors and electronic tape path control for the demanding computer
storage environment.
• Implementing a four-head design to provide read-after-write (RAW) error
correction and to maximize the benefits of the helical scan recording method,
namely: (1) high-density recording (all tape space is used by dense, overlapping
tracks at alternating azimuth angles) and (2) high-speed searches.
• Using second-generation audio and custom LSIs for efficient circuit layout and
increased reliability with low power consumption. These LSIs are quad-flat-pack
(QFP) designs that use complementary metal-oxide semiconductor (CMOS)
technology.
• Implementing the DDS-4 format.
• Using flash memory devices for easy firmware upgrades.
• Storing configuration information in the parameter block of flash memory.
• Enabling the user to access configuration information in the flash memory using
the SCSI MODE SENSE command and to program the flash memory using the
SCSI MODE SELECT command.
• Implementing custom C3 ECC 1, 2, and 3 and other error-correction techniques.
• Embedding a full-LSI SCSI controller with capability for SCSI-2 command sets in
single-ended SCSI DDS-DC models.
• Embedded 40 Mhz ARM CPU with cache
• 8-Mbyte SDRAM data buffer.
This chapter describes the Scorpion 40 DDS-4 drive in more detail and explains
implementation-specific information.
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