Filter
Top Products
Theory of operations Chapter 7
STT8000A Product Manual Page 71
Control circuits
The control logic module shown in Figure 7-1 includes a buffer manager to handle
data movement between the controller, the buffer, and the tape formatter. This
module also includes logic to perform ECC and CRC generation and testing,
WRITE/READ data formatting, head stepper control, and drive motor control.
The microprocessor directs all functions performed by the control logic. The
instructions are read from a flash EEPROM, which can be updated with new
firmware through a specially written tape cartridge.
The 512-KB DRAM data buffer allows the drive to maintain streaming when the host
cannot provide data continuously at the tape streaming rate.
The write driver receives data from the write formatter and generates write current,
causing data to be written on tape by the tape head.
The read channel amplifies and conditions the signal from the tape head and passes
it back to the read formatter.
The head stepper and drive motor both receive current from the control logic to
control the stepping of the head from track to track and to move the tape forward
and back across the tape head.
Head design
The recording/playback head is a state-of-the art, thin-film design—a thin-film
inductive write head paired with an advanced magneto-resistive read head. This
head design provides the drive with exceptional performance and reliability. The
material composition of the head also results in exceptional wear characteristics,
resulting in stable performance throughout the life of the drive.
Flash EEPROM
Because the drive uses flash EEPROM (electronically erasable, programmable
read-only memory), the drive firmware can be easily upgraded when new revisions
of the firmware are released. The circuitry includes 128 KB of flash EEPROM.
You can load new firmware by using a specially encoded firmware upgrade
cartridge.
Refer to chapter 4 for information about loading new firmware using a Seagate
firmware upgrade cartridge.
Sensors and switches
A number of mechanical and optical sensors and switches are integrated in the drive
design. The Cartridge In switch detects when a cartridge is fully loaded and
positioned against the A-plane datum of the cartridge. The Unsafe switch senses