OS/2 Museum

In the late 1980s and the early 1990s, the so-called Bus Wars raged. A few years after the PC/AT was released, it became clear that the ISA bus could not keep pace with faster CPUs and peripherals, especially graphics cards and SCSI HBAs.

IBM’s solution, Microchannel or MCA (1987) was technically excellent, radical, and ultimately a failure. Compaq and the “gang of nine” bet on EISA (1989), a less ambitious but in many ways very similar bus with one major difference—backwards compatibility. EISA was in practice even less successful than MCA and practically unheard of outside of servers and some workstations.

Around 1992, the VESA committee standardized the VESA Local Bus or VLB, geared towards but by no means limited to graphics cards, and designed primarily for the 486’s local bus. For about two years, VLB was very successful and graphics cards designed for VLB were unbeatable.

Around the same time, Intel worked on PCI, a bus which successfully learned from past mistakes. In late 1993, the first PCI systems and adapters became available, and PCI in combination with Pentium systems very quickly destroyed all competition.

For a short while, all five buses (ISA, MCA, EISA, VLB, PCI) existed in the market. Some adapters were available in two or three bus variants and a precious few went all the way. One of those was ATI’s mach32 graphics chip and the adapters based on it, Graphics Ultra Pro and Graphics Ultra + (using VRAM vs. DRAM, respectively).

The mach32-based ATI Graphics Ultra is a true child of  the bus wars. In 1994, ATI sold the Graphics Ultra in all five bus variants, something not imaginable any any other point in PC history. The OS/2 Museum presents the entire family: Five ATI mach32 graphics cards built in 1994.

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