Read And Write Lsi; Timing Tracking Circuitry; Scsi Controller; Flash Memory - Seagate STD124000N Product Manual

Theory of Operations

Read and Write LSI

Timing Tracking Circuitry

SCSI Controller

Flash memory

Product Manual
One high-speed, single-chip signal processor and audio DAT-formatter LSI provides
the read and write signals for each drive. The LSI is supported by a static RAM. This
chip is controlled by the controller microprocessor.
The timing tracking circuitry of the drive is designed to provide high precision
tracking and head positioning. The timing tracking system, in conjunction with the
four-head read-after-write (RAW) design provides for reliable high-density data
recording with maximum storage efficiency. For detailed information about timing
tracking implementation, refer to Chapter 6 on page 47.
The embedded SCSI controller circuitry in the drive is made up of several
components. A single chip DDS formatter LSI communicates with the
microprocessor and with the read and write LSI. The C3 ECC coprocessing
capability and the memory control function are also included in this single chip.
Other components vital to this circuitry are the high-performance SCSI core in the
SCSI/data-compression LSI chip, the microprocessor and the flash memory. The
standard dynamic RAM (DRAM) buffer is 2 Mbytes.
The SCSI/data-compression chip, which is a 100-pin PQFP, provides the SCSI core
and the DCLZ machine. The SRAM (compression memory) external to the device is
part of the SCSI controller circuitry. Refer to Section 7.3 for a more detailed
discussion of the SCSI/data-compression chip.
Because the Scorpion 24 uses flash memory, the drive firmware can be easily
upgraded when new revisions of the firmware are released. The SCSI controller
circuitry includes 512 Kbytes of flash memory on these models.
You can load new firmware in one of three ways:
z
Using a specially encoded firmware upgrade cartridge
z
Issuing a SCSI Write Data Buffer command to download the firmware to the
EEPROM
z
Through the drive serial port
Refer to Chapter 4 on page 33 for information about loading new firmware using a
Seagate firmware upgrade cartridge.
Chapter 8
Page 77