HL5.AUG– –RM
Graphical-user-interface accelerators use standard DRAMs
Low-end device caches a narrow frame buffer, while the higher-end device
goes to a 64-bit frame-buffer width
A pair of graphics accelerator chips brings high integration to two
price/performance points. The 64300 Wingine DGX graphics accelerator from
Chips & Technologies can make, with only six chips, a 1-Mbyte board that
will do about 20 million Winmarks for a retail price around $160. Cirrus
Logic's Alpine CL-GD543x family, on the other hand, has a 64-bit data
path, both internal and to the frame buffer. It will do 30 million
Winmarks, but its minimum frame buffer needs many more chips, if commodity
4-bit-wide dynamic RAMs are used. Both companies' chips integrate a 24-bit
RAMDAC, dual-output clock synthesizer, and VGA controller. In addition,
both have power-saving capabilities. Both chips come in 208-pin plastic
quad flatpacks. Chips & Technologies' approach, which it calls XRAM,
involves caching part or all of the frame-buffer data in compressed form.
The cache has two levels: 1.2 Kbytes primary internal and 128 Kbytes
secondary external. The external cache is in a standard 256-K x 4-bit
DRAM. The frame buffer can use either 256-K x 16- or 256-K x 4-bit DRAMs.
Using the 16-bit-wide configuration, a board with a 1-Mbyte frame buffer
and the 64300 has only six ICs on it, including the cache. On the 64301, a
cheaper version with internal cache only, the same configuration totals
five ICs. The 64300 chip includes VLbus and ISA interfaces. It performs all
256 Microsoft Windows raster operations. Chips & Technologies promises
drivers for Windows 3.1, Windows NT, OS/2, AutoCAD, and DOS. It will
supply a video BIOS. An evaluation kit for the 64300, due this month,
includes a VESA local-bus board, drivers, BIOS, and documentation. A PCI
version will be available next year. The Cirrus CL-GD5434 has glueless
VLbus and PCI interfaces and supports frame buffers up to 4 Mbytes. It can
refresh screens at 76 Hz and has a max dot clock of 85 MHz. It manages 64
K colors at 1,024 x 768 non-interlaced, and 1,280 x 1,024 with 256 colors.
(Alpine CL-GD5434, $39 ea/1,000–samples 3rd qtr, prod qty early 4th qtr.
Wingine DGX 64300, $29 ea/10,000; 64301, $26 ea/10,000–samples now.)
Chips & Technologies San Jose, CA Carlos Bielicki 408-434-0600, ext.
2260
Cirrus Logic, Inc. Fremont, CA Brent Wientjes 510-226-2123
3130
CAPTION:
The Wingine DGX graphics accelerator chip from Chips & Technologies
caches frame-buffer data, compressed and decompressed on the fly, in a
cache. This technique bypasses the frame buffer often enough to accelerate
graphics without a wide or fast frame buffer interface.
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