A computer processor developed by Intel as an upgrade to the 386 processor series and commonly referred to as the 486 or i486. The 80486 has 8k of memory cache BUILT into the processor with 32-bit databus architecture and was available in clock rates ranging from 20MHz to 33MHz. The 486 was available as either a DX or SX, the DX features a built in coprocessor, the SX does not. In addition to the 486SX, a 486SX2 was also available and was capable of doubling the speed. In the picture to the right, is an example of the Intel i486 SX processor with the OverDrive socket.

In 1990 the 486SL was introduced and utilized less power than the 486 and is mainly used in portable computers.
On April 1991 Intel released the 890486SX (codenamed P45 and P23) for $258.00 that ran at 16MHz, 20MHz, 25MHz, or 33MHz, a lower clock speeds than the DX.
On March 2, 1992 the 486DX2 (codenamed P24 abd P24S) was introduced and ran at double the clock rate of a 486. Thus, a DX2 on a system with a 33MHz bus would run at 66MHz. Alternatively referred to as the i486DX2.
In 1994 the 486DX4 (codenamed P24C and P24CT) was introduced, it tripled the clock rate of the 486 and has doubled the cache (16k). If you had a 33MHz it would make it a 100MHz. Note: there is no 486SX4.


*I enjoyed the read on the homepage of 486 historical timeline. I had a bunch of 486 machines which were purchased cheaply or given to me when the Pentiums and Athlon's were the processor to have in the late 90s and people were looking for a free computer removal solution VS paying the LANDFILL to dispose of them. For a while I was fixing them up and donating them to schools with no budget to afford computers. The last 486 I had was the 486DX4 100Mhz with 24MB Ram which I ran Windows 98 SE on. I ended up retiring this system in 2000 when the motherboard was not Y2K compliant and so everytime I booted the machine I had to change the date otherwise when surfing on the web security certificates would complain with out of date etc when running AOL 4.0 on 33.6k modem. With the 50+  486 systems that I worked on to put back into operation I was surprised that I only came by 1 AMD 486 processor system, a 40Mhz that was in a Compaq. Intel seemed to own the market back then I guess as far as CPUs went. These days I am thinking its more like 50/50 with Intel's and AMD's out there in peoples computers for CPU's, and back when I bought my Athlon XP 2800+ system in 2004 the usage was probably 33% AMD and 66% Intel. These days I prefer AMD to Intel due to price to performance COMPARISON. But up until 2004 I was strictly an Intel customer for CPUs.