DOS Days
Old PC Computing Resource
Cirrus Logic
Cirrus Logic was a graphics chipset manufacturer for the IBM PC and its compatibles. Founded in 1984 in Silicon Valley, their chipsets became very popular due to their low cost and high degree of compatibility. During the early 90s, when compared to other Windows graphics accelerator cards from Trident, Oak, and Paradise (Western Digital), the Cirrus Logic usually outperformed them all.
In 1991 the company acquired Crystal Semiconductor, an audio mixer/DSP chip company. In 1992 they bought AcuMOS, a video chipset company who designed and manufactured chipsets called "AVGA1" and "AVGA2". These were rebranded in late 1992 to the CL-GD naming format.
CL-GD410 / CL-GD420
The CL-GD410 and 420 was an ISA Super VGA chipset. This chipset can be found on the Video7 VEGA VGA card.
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CL-GD510 / CL-GD520
The CL-GD510 and 520 was an ISA Super VGA chipset, called "Eagle II". This chipset was known for its 100% hardware CGA emulation. Most cards that bore this chipset came with both 9-pin and 15-pin D-SUB sockets to support pre-VGA monitors and VGA/SVGA/Multisync monitors. The core was typically clocked at 40 MHz, as was the memory. I have one of these cards - it is an almost full-length 8-bit ISA card that runs the Eagle II VGA chipset. I dumped the VGA BIOS v2.12 here (the file is 64 KB but I believe the Eagle II is just in the first 32 KB so you will need to edit the file to make it work for re-burning). The Ultimate Oldschool PC Font Resource has this card's incredible font in its collection:
Used on the MaxLogic MX675, VIP VGP-II, Morse KP800-16, and VG-1000.
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CL-GD5320
The CL-GD5320 was an ISA Super VGA chipset. These cards, since they were VGA only, came with just the 15-pin D-SUB. The core clock ran at 40 MHz. Found on the CVGA-V3-256, VP442, VP44.
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CL-GD5401 The CL-GD5401 was an ISA Super VGA chipset, also branded as AcuMOS VGA, or AVGA1. AcuMOS were acquired by Cirrus Logic in 1992 who renamed their AVGA1 to CL-GD5401 and AVGA2 to CL-GD5402. This was the first fully-integrated VGA chip to market (built-in RAMDAC and clock generators), meaning the only external chips required were video memory and a VGA BIOS. They were sold on the basis of low price rather than high performance, but despite this, both the AVGA and its successor, the AVGA2 (CL-GD5402), are top performers! 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:
More Images
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CL-GD5402
The CL-GD5402 was an ISA Super VGA chipset, also branded as Acumos VGA, or AVGA2. AcuMOS were acquired by Cirrus Logic in 1992 who renamed their AVGA1 to CL-GD5401 and AVGA2 to CL-GD5402. Like the AVGA1, the AVGA2 was sold on the basis of low price rather than high performance, but despite this, both the AVGA (CL-GD5401) and AVGA2 are top performers! The AVGA2 chipset added support for up to 512 KB of video RAM over the AVGA1's 256 KB, which meant it could support all the AVGA1's video modes in addition to 640 x 480 in 256 colours, 800 x 600 in 256 colours and 1024 x 768 in 16 colours. Commodore included a CL-GD5402 in their 386SX-25 computers. Found on the following cards:
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CL-GD5410
The CL-GD5410 was an ISA Super VGA chipset. It was installed on low-to-mid range DRAM-based cards (accelerated), and some laptops. It is known for being among the first to integrate the graphics card components into a single chip (built-in RAMDAC and clock generators). |
CL-GD5420 / 5421
The CL-GD5420 was an ISA Super VGA chipset. Highly integrated (15-bit RAMDAC and PLL). The 5421 is a minor upgrade as it had a 16-bit RAMDAC, also commonly referred to as High Color or "Hi-Color". There was never a 24-bit "True Color" DAC for the 5420/5421. The core clock runs at 75 MHz, and memory at 50 MHz. Found on:
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CL-GD5422 / 5424
The CL-GD5422 was an enhanced version of the CL-GD5420, with a 32-bit memory bus and 15/16/24-bit RAMDAC, so supported True Color. It offered 1280 x 1024 interlaced or 1024 x 768 non-interlaced maximum resolution. The CL-GD5422 supported hardware acceleration for both 8-bit and 16-bit color depths. It was one of the lowest-priced SVGA controllers to support both. The core clock runs at 80 MHz, and memory at 50 MHz. A VESA Local Bus version of the 5422 is called the CL-GD5424 - it was their first VLB card. There is at least one anomaly I've noticed - the Ahead AVGA-A3 card listed below is a 16-bit ISA card that uses the CL-GD5424. I guess the 5424 provides a VESA local bus width but is fully backward-compatible to run on the 16-bit ISA bus too, so if parts were in short supply, CL may have offered up 5424s in place of 5422s. Can anyone clarify? Found on:
The CL-GD5424 was also the integrated VGA chipset used on AST Bravo 486 computers. |
CL-GD5425
The CL-GD5425 was the same as the GC5424 but also got a TV out connector. This was able to scale a full VGA display (640 x 480) into a TV viewing area while maintaining a correct aspect ratio. |
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CL-GD5429 / CL-GD5430
An enhanced version of the CL-GD5428 that first appeared in the first quarter of 1995 - the first in their new "Alpine" series of chips. What is new over prior GD-542x chipsets is the 5429/30 now supports a higher memory clock speed (32-bit memory bus) and has memory-mapped I/O. 32-bit BitBLT engine. The CL-GD5430 is similar to the 5429, but has a 543X core with 32-bit host interface. Only slightly faster than the 5428. Found on the following:
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CL-GD5434 / 5436
The Alpine family chip now with a 64-bit internal memory interface. Only supports 64-bit mode if equipped with 2 MB memory. Commonly equipped with 1 MB. 32bpp True Color support. 64-bit BitBLT engine. The CL-GD5436 was simply an optimized version of the 5434, adding support for EDO DRAMs thus supporting a faster memory clock. Packed-24 acceleration. Found on:
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CL-GD5440
Essentially a CL-GD5430 with an integrated CL-PX2070/'85 motion-video acceleration (CL-GD54M40 has integrated filters). The core clock runs at 86 MHz, the memory at 60 MHz. Found on:
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CL-GD5446
64-bit Alpine VisualMedia accelerator. 2D-only. Adds motion-video acceleration to the CL-GD5436. Found on:
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CL-GD546X
The Laguna VisualMedia family of 2D, 3D, and video accelerators. the CL-GD5464 and 5465 include 3D acceleration (PCI or AGP). These chips use a single channel of RDRAM memory, providing up to 600 MB/s bandwidth. The '62 lacks 3D acceleration. All include a BitBLT engine, video windows, and 64×64 hardware cursor. "Cirrus Logic claims it has the graphics accelerator equivalent of the Jaguar XJ220 on its hands. Its new VisualMedia accelerator, "catchily" named the CL-GD5462, can shift a whopping 500Mb of data around every second.
The device is crammed with technology which enables it to handle video and 3D work at jaw-dropping speeds. It numerous features include line and polygon drawing acceleration, hardware zooming, a 64-bit graphics engine and direct conversion from the different colour palettes found in film sequences to those used on PCs." PC Review, Iss.47, September 1995
Found in MSI motherboard add-in, MS4415 |
CL-GD5480
64-bit Alpine accelerator with 100 MHz SGRAM. |
Launched: 1991
