DOS Days

Cirrus Logic CL-GD5401

The CL-GD5401 was an ISA Super VGA chipset, also branded as AcuMOS VGA, or AVGA1. The chip first appeared prior to the AcuMOS acquisition by Cirrus Logic in 1992. It's not 100% clear, but the design of the chipset was likely done by AcuMOS (who called it AVGA1) and CL entered into an agreement to resell it under the CL branding before they bought the company. This would explain why some had the Cirrus Logic branding while others had AcuMOS AVGA1 branding.

Released 1991
Bus ISA 16-bit
Chipset Cirrus Logic CL-GD5401 / AcuMOS AVGA1
Standards MDA, Hercules, CGA, EGA, VGA
Memory 256 KB DRAM (70 or 80ns)
RAMDAC (Internal)
Part # -
See Also CL-GD5402

The CL-GD5401 was the first fully-integrated VGA chip to market, with a built-in RAMDAC and clock generators, meaning the the only external chips required to build a graphics cards were video memory and a VGA BIOS.

The chipset's core clock ran at 42 MHz, with memory running at either 37.5 MHz (if 80ns DRAMs are used) or 44.7 MHz (if 70ns DRAMs are used).

They were sold on the basis of low price rather than high performance, but despite this the CL-GD5401/AVGA is a decent performer for an ISA graphics chipset.

Found on the following cards:

Some of these cards are 16-bit ISA but still work in an XT's 8-bit ISA slot in "compatibility" mode, due to the chipset's ability to auto-sense the bus width and its support for 8- and 16-bit BIOS ROMs:



The chipset itself came in these revisions: B.



In 1991, cards using this budget chipset would have competed with the ATI VGA Charger or other cheap cards from Trident or Paradise. If you had more money you would opt for a Tseng Labs ET4000-based card such as the Diamond SpeedSTAR VGA, Everex Viewpoint VRAM, Orchid ProDesigner II, STB Powergraph ERGO-VGA, Trident Impact III, or Video Seven VRAM II.


In the Media

Setting it Up

There is no known setup configuration for cards that have a CL-GD5401 / AVGA1 chipset.


Operation Manual

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Original Utility Disk

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AVGA1 Datasheet

The AcuMOS AVGA1 datasheet

Eizo VA30 BIOS
Version A6, 30 Nov 1990

Phoenix VGA ROM BIOS from an Eizo VA30 card


More Pictures

From left: Eizo VA30, Boca Research AVGA1, United Solutions AVGA1, and Everex Systems EV-628 Viewpoint Standard

An AVGAIR-E06 card

A JAX8223 card

An EIZO VA30 card