Microprocessor. ENCAD T-200

CadJet T-200 Service Manual

Microprocessor

The microprocessor (an IBM PowerPC) is the central processor unit which supervises system functions, executes the printer firmware, manipulates data, and controls input/output data busses. It has two built-in serial ports, a two channel DMA (Direct Memory Access) controller, a timer module, clock generator, and an on-board chip select generator. One serial port connects to the Mini-DIN connector which can be used to communicate with the host computer; the other serial port interfaces to the Control Panel. One DMA channel supplies data to the gate array for jet firing; the other DMA channel is used to receive data through the parallel port via the gate array, or the serial port when using a high speed serial mode. One timer generates a servo interrupt every millisecond; the other is used for timing the Stepper

Motor.

The system is timed by a 33MHz system clock from an oscillator (Y1).

The chip select generator is programmed to generate chip selects at the appropriate addresses, with the appropriate data size (byte, word) and with the appropriate number of wait states.

Gate Array

PARALLEL

PORT

GATE

ARRAY

STATIC

RAM

Figure 2-5. Gate Array.

SERVO

CONTROLLER

MICROSWITCHES

TO

CARRIAGE

PWA

Theory of Operation 2-6