Inventors:
Michael G. Lavelle - San Jose CA
Claude A. Goldsmith - San Jose CA
Allin D. Kingsbury - San Jose CA
Assignee:
Motorola Computer Systems, Inc. - Cupertino CA
International Classification:
G06F 3153
G09G 106
Abstract:
In a video terminal comprising a terminal processor communicating with a central processor, and a single-block non-interleaved video memory for storing video information for displaying on the terminal screen, a video update FIFO buffer is provided for buffering video information between the terminal processor and the video memory. The 3-word FIFO buffer is filled during screen trace, and it transfers its contents into the video memory during screen retrace periods. The FIFO buffer permits screen information to appear without flicker. It also permits scrolling of row segment screen information by reading a row segment from the video memory, temporarily storing it, and then writing it into an adjacent row segment. It also permits flexible cursor symbols, cursor blinking of individual display screen areas, and certain data format conversions. In addition, the FIFO buffer is bidirectional, being able to both read data into and write data from the video memory, enabling information stored in the video memory to be accessed by the terminal processor for diagnostic purposes.