International Business Machines Corporation

Richard D Bolcavage

Arthur E Fleek

Armand J Ferraro

Michael D Hryck

Harold B Kinter

Mitchell P Marcus

William B Kauczka

A printer control system for a belt printer has an arrangement for checking print hammer operating circuits by comparing a real time actual parity of the circuits with a precalculated expected parity. Prior to printing, a microprocessor calculates expected parity bytes for each subscan for storage in a storage device along with the print position fire data used for selecting the operating circuits to be activated in the related subscans. An actual parity byte is generated on a real time basis by ODD/EVEN parity circuits associated with groups of operating circuits for comparison with a composite parity byte generated each subscan by the microprocessor. The composite parity byte is generated by combining the expected parity bytes from the storage device for several successive subscans. The composite parity byte is updated each subscan by a process of subtracting the initial expected parity byte and adding a new subscan expected parity byte. Comparison is made when all the activating circuits are in stable condition.

Printer system having parity checking of print hammers using software

A method and apparatus for testing print elements of a printer, such as a belt printer, in which the print element operating circuits are energized at an energy level insufficient to cause printing but sufficient to generate feedback signals for checking operativeness by a microprocessor.

Control system and method for testing print hammers in a high speed

A printer system comprising a belt printer mechanism controlled by a stored program digital microprocessor to print lines of data on a print medium. Selective operation of a linear array of print hammers, paper feeding, data conversion and arranging in scan/subscan order are performed by the microprocessor. The fire data for operating hammers is precalculated and arranged in scan/subscan order during the print medium feeding interval with printing occurring immediately at the first print scan after print medium motion in which one or more desired characters become aligned with print hammers. An indirect addressing technique which eliminates sorting is used to arrange the print position fire data in scan/subscan order.

Line printer system and method of operation with microprocessor control

A belt printer control system for attachment to a host system has a first microprocessor connected by a dedicated bus to the host system and control elements operable to perform carriage control, belt drive, and ribbon drive operations of the printer mechanism. A second microprocessor is connected by a dedicated bus structure to controls for operating the print hammers. A common RAM is accessed by the two microprocessors through a common bus structure. The first microprocessor passes control and print information to the RAM for use by the second microprocessor in building print algorithm tables in the RAM for use by the second microprocessor to operate the print hammers. Communication between the microprocessors is done through control information stored by the microprocessors in the common RAM. Storing printing information and building of tables and controlling printing and nonprinting operations of the print mechanism are done concurrently.

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Kirkwood, NY, United States of America

Richard D Bolcavage