Initialization; Communication Interface Control - Ithaca 75 User Manual

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Series 70 Maintenance Manual
The electrical section of the printer consists of the components shown in the
illustration on the previous page.
The Control Board contains the Microprocessor and its peripheral circuits, the
DC power circuit, and Printhead and Line Feed Motor drive circuits.
The Interconnect Board contains the Take-Up Motor and Cash Drawer Driver
circuits. It connects the Keypad, Carriage, Line Feed Motor, and Validation
Sensor to the Control Board.
The printer control signals from the host system (PC or termina) are brought
directly to the Control Board from the rear panel on standard printers (parallel
interface). On units with an optional serial interface, the host signals are
brought from the rear panel to a board attached to the Control Board.

INITIALIZATION

The printer is initialized when the power is turned on or when the parallel
interface signal, I-PRIME, is received from the host computer.
Initialization is started with the RSTOUT signal output from the reset circuit
(Q7 pin 13) to reset Q12 (micro-processor), Q4 (interface LSI), and 5 (motor
control LSI).
When resetting is completed, the program starts with mode setting of Q12, Q4,
and Q5, memory (ROM and RAM) check, AM initialization, and then carriage
homing. The program finally establishes the interface signals (output of ACK
signal, BUSY signal, etc.), lights the select indicator, and informs the host
system that the printer is ready for data reception (in the data reception wait
state). This completes the initialization routine.

COMMUNICATION INTERFACE CONTROL

Parallel Interface
Figure 50: Parallel Communication Sequence