Browse Prior Art Database

Page Reprint for Line Printers

IP.com Disclosure Number: IPCOM000074311D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 4 page(s) / 74K

Publishing Venue

IBM

Related People

Leavenworth, RL: AUTHOR

Abstract

This microprogram, when added to the controls of a high speed printer, allows the System* to recover from detected print errors or carriage position errors after the error may have been transferred to the output form. This function is accomplished without System* or manual intervention. Furthermore, it has the capacity to print repeated "master" copies without additional intervention from the CPU.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 51% of the total text.

Page 1 of 4

Page Reprint for Line Printers

This microprogram, when added to the controls of a high speed printer, allows the System* to recover from detected print errors or carriage position errors after the error may have been transferred to the output form. This function is accomplished without System* or manual intervention. Furthermore, it has the capacity to print repeated "master" copies without additional intervention from the CPU.

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 * Total Operating System composed of CPU, I/O and Programs. 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 SystemT with the exception of transferring commands, data and status information between units. The Page Reprint 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 Bit 1 and Bit 2 are specifically required for Page Voiding and are not described here. 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 Reprint is: 00D1 - Secondary Status - keeps track of the number

of times page reprint is repeated.

00D3 - Page Reprint Recovery Count - count of the

number of times Page Reprint routine was

successful.

1

Page 2 of 4

00D4 - Command Count - number of times Page Reprint

routine was entered.

The purpose of each Page Reprint Primary Status bit (PRPS) is to initiali...