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Chapter 7 Theory of operations
Page 70 STT8000A Product Manual
The following table shows clock frequencies used by the STT8000 drive
VCO Frequencies—All Derived from System Clock (42 MHz Crystal Oscillator)
Fundamental
Frequency
28 MHz 28 MHz 28 MHz 24.89 MHz
Channel
Frequency
9.33 MHz 7.00 MHz 4.667 MHz 3.11 MHz
Mechanics
The mechanical package for the STT8000 ATAPI minicartridge drive was designed
to provide all the advantages of easy cartridge loading and unloading while
maintaining the positioning accuracy necessary for high-density data recording. The
orientation of the cartridge is the same as the majority of QIC minicartridge drives in
the field.
Cartridge load mechanism
The cartridge is inserted in the drive by sliding it through the aperture in the bezel
and into a tray mechanism. When fully inserted the back portion of the cartridge
protrudes about 3/4-inch from the aperture. A switch is actuated at this point that
causes a microprocessor to complete the loading operation.
When the tape is in motion, the amber LED on the front panel flashes. The LED is
not lit when the tape is positioned at BOT.
Capstan drive motor assembly
In the STT8000 ATAPI minicartridge drive, the cartridge is driven by the
capstan/belt motor assembly, which is on a linear slide. The cartridge is loaded
against the cartridge drive roller which exerts a net radial dynamic force of 18 to 26
ounces. The motor is a brushless DC drive motor with integral capstan which is
designed to provide maximum reliability.
The motor operates from the 12V nominal supply and moves the tape at speeds
from 35 to 100 inches per second (IPS).
Chassis
The drive mechanism is mounted in a molded frame that provides the mounting
holes for the industry standard 3.5-inch by one inch form factor. A 5.25-inch
mounting kit is an available option. The bezel is a simple snap-on design that is
available in several standard and custom colors. The round, front-panel LED is
amber and indicates tape activity.