Using a Pseudo Refresh Buffer to Limit Display I/O and Thereby Increase Display Performance
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-15
In the version of the Display Access Method (DAM) before the DisplayWrite 4 (DW4) product, the display was always operated in alphanumeric mode, in which the display hardware is used to physically place the character patterns on the screen. Since character presentation was handled by hardware, the resulting display performance was very fast. In fact, performance was fast enough that minimizing display I/O was not a concern in the original design of DAM. In DisplayWrite 4, DAM is required to run the display APA mode. This mode essentially requires DAM software to perform the job of presenting the character patterns on the screen (the job that display hardware performs in alphanumeric mode). The impact of using software to implement a function performed by hardware in alphanumeric mode is minimized by the following method.