Digital Equipment RW504-ZA, Service Manual

Page: 153 / 220

• Multifunction Peripheral Chip
Figure 6–2 Autochanger Controller PCA Block Diagram
The MICROPROCESSOR is a Motorola 68000 running at 12 MHz. This
microprocessor controls all processes on the controller PCA such as servos, SCSI
interface, and commands to the control panel.
Associated with the microprocessor is clocking circuitry, battery-backed-up RAM,
decoding logic, and ROM.
The MOTOR CONTROL CHIP (MCC) is the interface between the 68000
processor and the motors. The MCC reads the position encoders via Schmitt
triggers and uses that information to increment or decrement counters on the
chip. The MCC also provides Pulse Width Modulation (PWM) output signals to
drive the motor circuitry.
The SPIFI chip handles the SCSI protocol of the SCSI interface.
Theory of Operation 6–5