The Intel 80486 (i486, 486) is a range of Intel CISC? microprocessors which is part of the Intel 80x86? family of processors. |
The Intel 80486 (i486, 486) is a range of Intel CISC? microprocessors which is part of the Intel x86 family of processors. |
*[Intel 80486DX-2]? - runs at twice the external clock rate. *[Intel 80486SX-2]? - runs at twice the external clock rate, FPU disabled. |
*[Intel 80486DX2]? - runs at twice the external clock rate. *[Intel 80486SX2]? - runs at twice the external clock rate, FPU disabled. |
*Intel OverDrive? - 486DX-2 with a slightly different pinout for use in 486SX systems. *[Intel 80486DX-4]? - runs at quadruple the clock rate. |
*Intel OverDrive? - 486DX2 with a slightly different pinout for use in 486SX systems. *Intel 80486DX4 - runs at quadruple the clock rate. |
Based on material from FOLDOC, used with permission. |
Based on material from FOLDOC, used with permission. |
The 486s are very similar to their immediate predecessor, the Intel 80386. The main differences are that the 486 has an optimised instruction set, has an on-chip unified instruction and data cache, an optional on-chip [floating-point unit]? (FPU), and an enhanced bus interface unit. These improvements yield a rough doubling in performance over an Intel 80386 at the same clock rate.
There are several suffixes and variants including:
External clock rates include 16MHz, 20MHz, 25MHz, 33MHz, 40MHz and 50MHz.
The 486 processor has been licensed or reverse engineered by other companies such as IBM, AMD, Cyrix?, and [[Chips & Technologies]]. Some are almost exact duplicates in specications and performance, some aren't.
The successor to the 486 is the Pentium.