EP 0279662 A2 19880824 - Video memory interface circuit.
Title (en)
Video memory interface circuit.
Title (de)
Schnittstellenschaltung mit Videospeicher.
Title (fr)
Circuit interface à mémoire vidéo.
Publication
Application
Priority
US 1628487 A 19870219
Abstract (en)
A video display circuit (10) receives and stores character code data provided by a processor (12) and supplies character pixel data in the form of a video signal to a video display device (14). The circuit (10) includes a controller chip (16) and four memory chips (18-22), including a character memory chip (18) that stores the character code data received from the processor (12), and a font memory chip (22) that stores the character pixel data, or bit-maps, of each character of the character set. The data output pins (D) of the character memory chip (18) are connected to several of the address pins (A) of the font memory chip (22) to directly select within the font memory chip (22) a block of memory cells containing a character bit-map corresponding to character code data output by the character memory chip (18). Other address pins of the font memory chip (22) are connected to the controller chip (16) and select a row of memory cells within the block of memory cells. The data output pins (D) of the character memory chip (18) are also connected to the controller chip (16) for use in a pure graphics mode in which a portion of a full screen of graphics data is stored in the character memory chip (18).
IPC 1-7
IPC 8 full level
G09G 5/00 (2006.01); G09G 5/22 (2006.01); G09G 5/24 (2006.01); G09G 5/40 (2006.01)
CPC (source: EP)
G09G 5/40 (2013.01)
Designated contracting state (EPC)
DE FR GB IT NL
DOCDB simple family (publication)
DOCDB simple family (application)
EP 88301353 A 19880218; JP 2408588 A 19880205