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Chapter 1: GENERAL INFORMATION
1.1:
INTRODUCTION
The printer is a serial matrix printer capable of producing highly legible copy on forms
containing as many as six parts. It is well suited to a variety of applications. The standard
ASCII code is employed, and communications may be performed over a serial interface at
BAUD rates ranging from 110 to 19,200. A TTL parallel interface is also standard and is
compatible with the Centronics convention.
The standard set of 96 upper and lowercase ASCII characters is printed in a 9-high by 7-
wide dot matrix. True lowercase descenders and simultaneous underlining are possible
because of the 9-wire printhead. Forms varying in width from 3 to 15 inches may be fed
through the front or bottom of the printer, and a lever is provided to allow the user to adjust
the head-to-platen gap for multi-part forms. Inking is performed by an easy-to-change
cartridge ribbon.
A unique 16-key pad is located on the top cover which allows the user to define or alter
any machine feature. All features, including forms status, are saved in a nonvolatile
memory making setup quick and simple. An LED display is provided to function as an
enunciator in Setup mode, and to show the line number in normal print mode.
1.2:
FUNCTIONAL DESCRIPTION
The printer prints characters in a serial fashion by moving a 9-wire printhead in a bi-
directional manner along the print line. The direction of print is determined by a text
optimization routine, and is designed to maximize throughput by minimizing head motion
during nonprinting intervals.
The printhead is mounted on a carriage assembly which travels on two steel shafts. The
carriage is driven left and right by steel cables which are connected to a stepper drive-
motor. Two additional cables drive the ribbon advance mechanism which is part of the
carriage assembly. Paper is advanced by a stepper motor linked to a pin-feed tractor system
through a small rubber timing belt. A single microprocessor controls the mechanical
assemblies and handles the functional protocol for the printer. The microprocessor, along
with its peripheral circuits, operate in conjunction with the carriage stepper motor to
synchronize dot formation so that no encoder is required.
1-1
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