Browse Prior Art Database

Raster Scan Display Device SYNC Generation

IP.com Disclosure Number: IPCOM000048560D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 6 page(s) / 61K

Publishing Venue

IBM

Related People

Dunik, SL: AUTHOR

Abstract

This article is directed to a method and adapter apparatus to permit display terminals having different synchronization and data format requirements to interface with and use image data provided from a single transmitter or central processing unit (CPU). Line and frame fly-back information is embedded in the data stream and decoded by a universal converter attached to each receiver. No modification of the CPU or receiver is required.

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Raster Scan Display Device SYNC Generation

This article is directed to a method and adapter apparatus to permit display terminals having different synchronization and data format requirements to interface with and use image data provided from a single transmitter or central processing unit (CPU). Line and frame fly-back information is embedded in the data stream and decoded by a universal converter attached to each receiver. No modification of the CPU or receiver is required.

The invention overcomes a problem that terminals having different synchronization and format requirements are not presently usable with data sources for which they were not previously designed. For instance, with this invention an IBM data source can interface with non-IBM terminals.

Initially, a CPU or like unit generates data which is to be displayed at a remote location. This data is typically received a page or a full screen image at a time. Sometimes this data may include the synchronization information; in other instances the synchronization information may have to be added at the display device.

The data received in bit form is then loaded by the adapter 1 (Fig. 1) into picture data storage 10, which may consist of one 4 by 256-bit memory for storing color codes and two 4 x 256-bit memories for storing line count. The color code is used to designate the color to be displayed on the screen of the display device, whereas the count determines the number of dots of that color which are to be displayed with that color. For example, data received from the central processing unit may indicate that the color to be displayed is red and the length of the displayed line is to be 200 dots. This information would be recorded in the appropriate positions in the picture element storage. After a complete display image has been received and is recorded in storage 10, the storage is then available for addressing by the display device (not shown). The address is selected by the picture element storage address counter 12 which starts at position 0 and works through to position 255 so that the information stored in the picture storage 10 is accessed in sequence.

As the information in the picture element storage 10 is accessed, it is transferred to the code detector interface circuits 13 comprising color storage, synchronization detector and a picture element counter which receives the color code or synchronization pulse code so that a signal can be generated to the display 11 indicating what color is to be displayed or whether a synchronization pulse is required. The length of the color to be displayed or synchronization pulse to be generated is loaded into the picture element counter, normally in complement form, so that the incremental counter would increment upwards to an overflow condition. The counts in the counter represent the length of color to be displayed, as previously indicated, or the length of the sync pulse to be generated. The sync pulse requires a differen...