Kodak 800 SERIES service manual Interface Circuits Serial & Parallel

NovaJet 800 Series Service Manual

A hardware counter in the gate array increments as the Carriage Assem- bly moves left and decrements as the Carriage Assembly moves right. The hardware counter is only eight bits wide, so it cannot store a value large enough to represent an absolute Carriage Assembly position. Instead, it is read during the servo interrupt and its value compared with that from the previous interrupt. This difference is used to update the absolute position value in the software.

Interface Circuits: Serial & Parallel

MICRO-

PROCESSOR

GATE ARRAY

PARALLEL

CONNECTOR

Figure 2-10. Interface Circuits.

Data from the host computer is received through the Centronics parallel port. The gate array provides the control signals for DMA transfers from the parallel port to SDRAM.

The serial port is not used.

Possible solutions for the Macintosh computer user include using the print server device with an established network or installing a parallel port add- on card in the computer to interface with the printer.

Theory of Operation 2-15