Browse Prior Art Database

Direct Printing of a CRT Display Image

IP.com Disclosure Number: IPCOM000046716D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Poleschuk, NA: AUTHOR

Abstract

Printer adapter 10 captures video data 11 directly from a CRT display adapter, stores it as a multi-pel-wide column, then sends it to a thermal or other printer as a 90-degree rotated image. When the printer PRINT SWITCH is depressed, control logic 12 resets print-line counter 13, which keeps track of the current printer line. Counter decoder 14 controls the top and bottom margins and presets column-position counter 15. Counter 15 keeps track of which n-pel-wide column is about to be stored in the column buffer. Segment-displayed counter 16 keeps track of the current n-pel-wide segment of a horizontal CRT display line. Video data 11 is continuously shifted through n-bit shift register 17.

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Direct Printing of a CRT Display Image

Printer adapter 10 captures video data 11 directly from a CRT display adapter, stores it as a multi-pel-wide column, then sends it to a thermal or other printer as a 90-degree rotated image. When the printer PRINT SWITCH is depressed, control logic 12 resets print-line counter 13, which keeps track of the current printer line. Counter decoder 14 controls the top and bottom margins and presets column-position counter 15. Counter 15 keeps track of which n-pel-wide column is about to be stored in the column buffer. Segment-displayed counter 16 keeps track of the current n-pel-wide segment of a horizontal CRT display line. Video data 11 is continuously shifted through n-bit shift register 17. When comparator 18 detects a match between counters 15 and 16, shift register 17 stops, and the n-bit-wide video data word therein is stored in column buffer 19 during the next horizontal retrace of the CRT. Its address in buffer 19 is determined by write-address counter 20, via selector 21. Counter 20 is then incremented, and selector 21 gates read-address counter 22 to buffer 19. This allows data to be read from buffer 19 and shifted to the printer during horizontal- trace time. At the end of an entire vertical frame of the CRT, an n-bit-wide column of data has been stored in buffer 19. During the next frame, this data is shifted to the printer in single-bit-wide columns to be printed. This frame is divided into n equal intervals. SHIFT R...