Star Micronics TSP400 Theory Of Operation, 1. 1 Control board, Block Description, 1. 4 Power unit

THEORY OF OPERATION

1. 1 Control board

The interface board relays data from the host computer to the main board. The main board’s CPU stores the data into local RAM.

It then reads out the data, edits it according to the control program stored in the board’s ROM, and prints the results by issuing appropriate drive signals to the printer mechanism.

[Block Description]

a.CPU: HD641300F10T CMOS single-chip computer Controls overall printer operation.

b.EPROM: 128 K × 16 bits Contains the CPU control program.

c.PS-RAM: 128 K × 16 bits Work area and data buffer

d.S-RAM

Saves format data and externally defined characters. Backed up by super capacitor.

e.EEPROM: 1024 bits

Stores printer settings. Settings can be changed by software. (Used in place of dip-switches.)

f.Interface board

Interfaces the main board with the host computer.

There are three versions, each for a different interface type: RS232C, RS422A, or Centronics parallel.

g.Gate array

Executes various types of signal processing.

h.Drivers

The various drivers convert signals received from the CPU and gate array into the drive signals that directly control the printer mechanism.

i.DC-DC converter

Converts the supplied 24V to 5V.

1. 2 Control Panel

Provides manual control switches and operational indicators.

1. 3 Printer mechanism

Comprised of thermal head, paper-feed motor, and sensor mechanism.

1. 4 Power unit

Converts primary power to DC24V.

1. 5 External device

External device (such as cash drawer) driven by signals issued by the control board.

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