Browse Prior Art Database

Liquid Crystal Display Pel/Driver Diagnostic Test

IP.com Disclosure Number: IPCOM000039451D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Baier, KJ: AUTHOR [+2]

Abstract

A method is described to provide a pel/driver test that allows utilization of existing IBM Personal Computer (PC) cathode ray tube (CRT) display adapter diagnostic code with minimal modifications to test a liquid crystal display (LCD) and LCD controller. Diagnostics are tests that are used to test a base system and I/O functions that require user interaction, intervention or long execution time for verification of correct system operation. Previous IBM PC systems used CRT-type displays. On this type of display, the image is painted on the screen by intensity modulating an electron beam that is deflected by applying an analog electrostatic or electromagnetic force. The LCD displays an image by incrementing row and counter registers.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 1 of 1

Liquid Crystal Display Pel/Driver Diagnostic Test

A method is described to provide a pel/driver test that allows utilization of existing IBM Personal Computer (PC) cathode ray tube (CRT) display adapter diagnostic code with minimal modifications to test a liquid crystal display (LCD) and LCD controller. Diagnostics are tests that are used to test a base system and I/O functions that require user interaction, intervention or long execution time for verification of correct system operation. Previous IBM PC systems used CRT- type displays. On this type of display, the image is painted on the screen by intensity modulating an electron beam that is deflected by applying an analog electrostatic or electromagnetic force. The LCD displays an image by incrementing row and counter registers. Since the CRT display adapter and LCD controller are similar, the CRT display adapter tests were modified to test the LCD and LCD controller. However, since the LCD technology is different from that of the cathode ray tube, a new test is added to test the LCD. The method used to accomplish this test depends on the current LCD mode. If a CRT adapter is attached to the system, then the LCD is emulating a monochrome display. The regen memory buffer is mapped to address hex B0000, and the control registers are mapped to the 3BX range. In this mode, only text can be displayed. In text mode all pels are turned on by writing 2000 (80X25) "Block" characters (hex DB) to the regen memory buffer. This will fill the screen with 25 lines of 80...