Digital processor for generating alphanumeric display on a cathode ray tube
US4109244A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 1976 |
| Grant date | Aug 22, 1978 |
| Priority date | — |
| Expiry date | Sep 8, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G5/227
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A CRT display system is connected to a central processing unit over a bus and includes a random access memory which is filled and modified under the control of the computer and contains a sequence of codes defining characters to be displayed on the screen in successive locations. An oscillator controlled divider chain increments an address counter and also provides vertical and horizontal synchronization and retrace signals. A character generator which receives a character code from a RAM location designated by the counter as well as timing signals from the divider chain controls intensity modulation of the CRT display. Multiplexers interposed at various points in the divider chain receive the output of several stages of the preceding divider and operate under control from the CPU to determine which output is provided to the next element in the chain, thereby controlling the character size and spacing on the screen. During the vertical retrace a signal is provided by the divider chain to the CPU and major changes are made in the contents of the RAM. When the CPU is changing the RAM contents during the display process, the character being provided by the CPU is provided to the chara…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.