User's Manual

DAT 72/DDS-4 Product Manual

Motors and Control Circuits

The drive uses four direct-drive, brushless motors—the capstan, cylinder and two

reel motors. Using these small, direct-drive motors provides maximum reliability. The

cylinder motor rotates the cylinder. The capstan motor moves the tape. The mode

motor loads and ejects the cartridge. The two reel motors turn the tape reels.

The cylinder, capstan and reel servos are controlled by custom ASICs and the

motor-control firmware.

The fifth motor in the mechanism is a brush-type mode motor. This motor controls

(selects) the mechanism mode. Because the mode motor is not frequently used, and

due to space and torque requirements, a brush-type motor is best suited to this

application. The mode motor performs the mode changes as directed; for example,

this motor conditions the mechanism to eject the cartridge.

Timing Tracking Circuitry

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.

Signal-Processing Electronics

The signal-processing electronics circuitry in the drive is made up of several

components. The drive’s main control microprocessor, data engine, and data buffer

management circuitry are all integrated in a single IC package. A single-chip DDS

formatter LSI communicates with the microprocessor and with the read and write

LSIs. The C3 ECC coprocessing capability and a second buffer memory control

function are also included in this IC. Other vital components are the high-

performance SCSI LSI chip, the flash memory, and the DRAM buffer memory.

Flash Memory

Because the drive uses flash memory, the drive firmware can be easily upgraded

when new revisions of the firmware are released. The flash memory is 1 Mbyte in

size.

You can load new firmware in one of three ways:

Using a specially encoded firmware upgrade cartridge

Issuing a SCSI Write Data Buffer command to download the firmware to the

EEPROM

Through the drive serial port