Tseng Labs ET4000

The Tseng Labs "ET4000" was a popular graphics accelerator chip during the early 1990s, commonly found in many 486 and compatible systems.

At introduction (1991), the original "ET4000" was notable for its outstanding host-interface (ISA) throughput. Twice as fast as VGA-chips from Trident Microsystems and Oak Technologies, the ET4000's only superior was a VRAM-based board from Video 7 along with ATI's "VGAWonder+". Hardware GUI acceleration had not yet become mainstream, and so host-throughput was the dominating factor in a graphical-application's redraw speed. Equipped with an ET4000, a raw Windows PC would scroll text-windows noticeably faster and more smoothly. (According to Richard Ferraro's book "Programmer's Guide to EGA, VGA", the original ET4000 devoted as much as 30% of its silicon die area to a large host-interface FIFO.)

Hardware acceleration was introduced in the "ET4000/W32". Although the "W32" maintained Tseng's stellar host-interface throughput, hardware-acceleration reduced its importance (except for DOS). By the time PCI Windows accelerators became commonplace, Tseng's high host-throughput was no longer a distinguishing feature. Nevertheless, as a mid-priced Windows accelerator, the "W32" benchmarked favorably against competing S3 and ATI chips.

None of the members of the "ET4000" family offered an integrated RAMDAC. By the time the "W32p" was introduced, the lack of this feature harmed Tseng's competitiveness. Still, the "W32p" was used on several popular mid-range VLB-based video cards. "W32p" offered solid Windows GUI acceleration at a reasonable price, along with considerably competent DOS VGA performance. Tseng carried this DOS performance along with them with their later "ET6000" accelerator.

Tseng Labs' chipsets were part of many companies' lineups, notably with Hercules' "Dynamite" series, the Diamond "Stealth 32" and several "Speedstar" cards, and on many generic boards.

Models

*ET4000AX - Old ISA chipset, VLB OK (16-bit host interface, good response), up to 2MB video RAM.
*ET4000/W32 - Accelerated 32-bit host interface. 32-bit memory interface. Fair performance, comparable to Cirrus Logic CL-GD5426. Windows accelerator (up to 4MB)? Supported ISA, EISA, and VLB.
*ET4000/W32i - enhanced memory controller (32-bit wide with interleaving with 2MB -- similar to S3 805i, resulting in 85% the performance of a plain 64-bit bus). Very fast BitBLTs (efficient memory arbitration).
*ET4000/W32p (1994) - PCI interface, also used with VLB. Special video support. Several revisions, significant variation. Revisions before C or D may have crippled/broken PCI performance.

References

* [http://www.computercraft.com/docs/Videochipsets.html "PC Video Chipset Information"] by Michael Scott & Harm Hanemaayer, February 19 1997, retrieved January 2 2006