Browse Prior Art Database

Display Memory and Character Generator Testing

IP.com Disclosure Number: IPCOM000051237D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ko, MA: AUTHOR

Abstract

In a text display system having a large random-access dynamic storage and a pair of static row buffers interposed between the dynamic storage and a character generator, the storage, row buffers, and character generator are tested in a two-operation sequence by first testing the dynamic storage and then testing the combination of the static row buffers and character generator. The present technique is particularly applicable to the second of these two operations.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 80% of the total text.

Page 1 of 1

Display Memory and Character Generator Testing

In a text display system having a large random-access dynamic storage and a pair of static row buffers interposed between the dynamic storage and a character generator, the storage, row buffers, and character generator are tested in a two-operation sequence by first testing the dynamic storage and then testing the combination of the static row buffers and character generator. The present technique is particularly applicable to the second of these two operations.

After the dynamic storage has been separately tested, the groups of storage locations in the dynamic storage corresponding to displayable rows are each loaded with identical test data. Both of the row buffers are alternately filled so that after two row times both row buffers contain the same set of data. Using the technique described in the IBM Technical Disclosure Bulletin 24, 4556-57 (February 1982), the clock that provides timing to each of the memories is stopped. Although data in the dynamic storage can no longer be guaranteed due to the stopping of the clock, the static row buffers continue to store valid data. The row buffer contents are then transferred, one byte at a time, to the character generator for generation of the video bits from the row buffer test data bytes. The video data is then transferred at a substantially slower than normal rate over a single data line to a microprocessor for comparison with valid video data corresponding to the test...