EPSON AMERICA, INC.
Product Support Bulletin
Subject: ActionDesk 4000 Local Bus Video Information
Page(s): 1 of 1
The purpose of this bulletin is to provide information on the ActionDesk 4000
Local Bus Video Controller.
The Local Bus Video Controller in the ActionDesk 4000 computer is a
Cirrus Logic CL-GD5426. The controller provides better response time capabilities in
high frequencies and buffered inputs in order to avoid the cpu load.
The real performance of the video controller comes from the video accelerator inside
the controller that executes Windows graphics commands, off-loading the emulation
functions from the
In the Windows GDI, one of the most important of the graphics functions is the
Bit-Blt (Bit-Blocks Transfers) operations. The CL-GD5426 BitBlt hardware emulation
does not kick-in unless you work with 8 or 16 bit per pixel (256 colors or higher).
Otherwise you get standard performance in VGA and SVGA colors and resolutions.
However, the performance iimproves rapidly when increasing the number of colors.
To take advantage of the Cirrus Logic CL-GD5426, the following conditions are
Use a minimum of 256 colors. The more colors, the better performance.
Use external cache to allow the system to generate burst transfers for
large amounts of graphics data.
Run SETUP - Select ADVANCED SYSTEM SETUP then select MEMORY
CACHE. Set the CACHE WRITE WAIT STATES to 0 ZERO, and BURST
TRANSFER RATE to 2-1-1-1.