Alphanumeric Display Logic
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
The use of video RAMs (random-access memories) for the character buffer in a multipage high function alphanumeric color display is described These are dual ported DRAMs (dynamic random-access memories). One port is used for random access by a microprocessor, and the other port is via a shift register which is loaded with a complete row of array character codes and display attributes in one DRAM cycle and and is connected to screen refresh logic. A conventional design for an alphanumeric display is shown in Fig. 1. This uses a character buffer in which coded information for each character on the screen is stored. This buffer contains the address of the required pel (picture element) patterns in the character generator and also the highlight display information for each character.