Monday, 22 April 2019

Intel 80486 (1989)

Intel 80486DX-25
Announced April 1989

Early PCs were slow. Really slow. Even in the late 1980s, many were still based on the decade-old Intel 8086. Successive generations of CPU were better, the 80286 was faster, the 80386 helped to bring in multitasking but it wasn’t until 1989 that Intel finally came out with a processor that could considered as fast – the Intel 80486.

The 80486 (often known as the “486”) built on the architecture of the 80386, combining it with an 80387 maths co-processor, 80385 cache controller plus a whole lot of other optimisations to come up with something that was twice as fast as the 80386 for any given clock speed. Initially launched running at 20 and 25MHz, by 1994 the clock rate was pushed up to 100MHz in the IntelDX2. For users on a budget, the maths co-processor was removed to create the 486SX.

Hand-in-hand with the 486 was the VESA Local Bus (VL-Bus) which was used primarily with graphics cards to bypass the bottlenecks in the old 16-bit ISA bus that most PCs had. This made 486 PCs significantly better for games and other graphically-intensive work, although the VL-Bus itself was very much tied to the 486 architecture and effectively became extinct when the Pentium first came out.

It took until 1990 until the 486 was available in quantity, however the first 486-based computer was the British Apricot VX FT server, launched in September 1989. The 486’s architecture helped to introduce plug-and-play into Windows, and it remained competitive even when its successor was launched, with the cheaper 100 MHz 486 outpacing the expensive 60 MHz Pentium. But of course times would change. Intel kept various models of the 486 in production until 2007. Rival companies also made 486s, some under licence and others reverse-engineered in some way.

It turns out that old processors are somewhat collectable, but generally these tend to be 1970s CPUs rather than later ones. Still, if you find yourself in need of a particular 486 for some reason, you can probably find one on eBay.

As for the name… the 80486 was the last processor of its type to be named with a number, following on from the 8086 launched 11 years earlier. The reason for this was that numbers cannot be trademarked in many jurisdictions, so the next generation was named the “Pentium” which was a nod to the “5” in 80586 if Intel had continued with their naming pattern.

Image credit: Andrzej w k 2 via Wikimedia Commons


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