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Page Voiding for Line Printers

IP.com Disclosure Number: IPCOM000073859D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 93K

Publishing Venue

IBM

Related People

Leavenworth, RL: AUTHOR

Abstract

This microprogram, when added to the controls of a high speed printer, insures that a form on which a detected print or space error has occurred is unreadable. This function is accomplished without System* or manual intervention by overprinting the page in error with "void" information. * Total Operating System composed of CPU, I/O and Programs.

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Page Voiding for Line Printers

This microprogram, when added to the controls of a high speed printer, insures that a form on which a detected print or space error has occurred is unreadable. This function is accomplished without System* or manual intervention by overprinting the page in error with "void" information. * Total Operating System composed of CPU, I/O and Programs.

The printer control unit referred to here consists of a small microprogrammed CPU type data flow containing Read-Write Storage, a changeable control storage for the microprogram routines, an adder, and a priority sequencing organization to execute the various printer functions at the correct intervals. Contained within the control storage are also software counters such as the Reprint Buffer Line Counter and Character Per Line Counter. Storage referred to is byte-orientated (8 parallel data bits plus a parity bit) for both the micro-instructions and data information. Three storage areas or segments are defined as "buffers" for printer synchronization. These are the Reprint Buffer (RB) with a capacity to hold one printable page of data, the Print Line Buffer (PLB) with a capacity to hold a single line of printable data, and a Carriage Control Buffer (CCB) with a capacity to hold the vertical line formatting information (spacing and skipping) for a single form. Operation of the printer is independent of the System* with the exception of transferring commands, data, and status information between units. The Page Voiding Program utilizes microprogram routines in conjunction with common control unit hardware to perform these functions.

These routines are entered from a polling routine which is sequentially testing various printer status conditions. Following the testing of PRS (Polling Routine Status) Bit 3 which is the Page Reprint status bit, the Page Reprint routine will be entered if PRS Bit 3 = 1, signifying an error condition.

The Page Reprint and Page Voiding routines are divided in six subroutines, of which PRPS Bit 1 and PRPS Bit 2 are two subroutines specifically required for Page Voiding. Each subroutine provides one of the functions as shown below. Bit 0 - Page Reprint Initialize

Bit 1 - Carriage Reverse

Bit 2 - Forms Voiding

Bit 3 - New Forms Advancement

Bit 4 - Reprint Buffer to Print Line Buffer

Transfer

Bit 5 - Ending and Logging. These bits are referred to as Page Reprint Primary Status and reside in storage location defined here as 00D0. Other data maintained in storage for Page Voiding is: 00D2 - Void Line Count - number of lines on the form

in error to be printed with "void" data.

The purpose of each Page Reprint Primary Status bit (PRPS) is to initialize a subroutine to set up the necessary constants, flags, and hardware conditions required of other routines such as carriage routines and RB (Reprint Buffer) to PLB (Print Line Buffer) transfer. These routines are entered from the polling program and executed.

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The Page Voiding micr...