Operator`s manual

1.9: NON-VOLATILE MEMORY
A non-volatile memory (NVM) is used to store all programmable printer parameters.
Included are such things as forms length, BAUD rate, tab position, communications status,
etc. The forms line number is saved in the NVM so that top-of-form position is maintained
at all times unless the form is manually moved by the operator.
At power-on, if an error is detected, an error code of 6508 will be written into the 4-digit
LED display on the control panel. Otherwise, operation of the printer will commence with
all features and status configured as they were when power was last switched off.
Any changes are made during normal run time as needed. The only exception is in the
event of a default reset. In that case, a special set of feature values are loaded into the
NVM. A checksum is computed and saved along with the data for error detection at the
next power on cycle.
1.10: RIBBON DRIVE SYSTEM
The printer employs a continuous loop cartridge ribbon for inking. The ribbon cartridge
mounts on the carriage assembly where it registers to two guide posts and engages the
drive mechanism. A pair of spring clips serve to “hold-down” the cartridge to the carriage.
The drive mechanism is a mechanical device which derives its power from motion of the
carriage. Power is coupled to it from two steel cables strung between the left and right
endplates. Each cable is wrapped (1 turn) around a pulley which contains a unidirectional
clutch bearing. The cables are strung in a fashion that causes the pulleys to rotate in
opposite directions. The clutch bearings are oriented in each pulley so that one pulley
drives while the other idles. Thus, the ribbon drive shaft always rotates in a
counterclockwise direction. This is necessary since the ribbon cartridge cannot reverse. A
spring loaded plunger is pan of the ribbon drive shaft assembly, and it is the device that
engages the spindle on the cartridge.
1.11 CARRIAGE DRIVE SYSTEM
The carriage drive system consists of a permanent magnet stepper motor and a power
amplifier which drives the carriage through two steel cables. The motor has an angular
resolution of 1.8 degrees in full-step mode, and 0.9 degrees in half-step mode. The drive
ratio between the motor and carriage is such that one full-step equals 0.010 inch linear
travel. The relationship between step angle and linear motion serves as the foundation for
positioned control, and dot synchronization during character formation.
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