The X 86 Microprocessors: Architecture, Programming and Interfacing (8086 to Pentium) 2nd Edition by Pearson

14-42

THE

x86 MICROPROCESSORS

here has to give an idea of the capabilities of one of the more sophisticated processors of

the Intel family. The 80486 and Pentium have all these features, so these sections have to

be understood for appreciating the characteristics of Pentium.

14.14 | Enhanced Features of 80486

i) The 80486 processor was introduced by Intel in 1989. The first important difference

that the ’486 has in comparison with its predecessor is that it has an integrated float-

ing point unit on the chip itself. Previous processors had the arithmetic unit as a sepa-

rate unit – the 8086 had 8087, the 80186 had the 80187, the 80286 had the 80287,

the ’386 had the ’387 and so on. Logically, the 80486 should have had an arithmetic

co-processor ...