The 8088 and 8086 microprocessors pdf


Introduced on July 1, 1979, the 8088 had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however.

The original IBM PC was based on the 8088. The 8088 was designed in Israel, at Intel’s Haifa laboratory, as were a large number of Intel’s processors.

The prefetch queue of the 8088 was shortened to four bytes, from the 8086’s six bytes, and the prefetch algorithm was slightly modified to adapt to the narrower bus. These modifications of the basic 8086 design were one of the first jobs assigned to Intel’s then new design office and laboratory in Haifa, Israel.

Variants of the 8088 with more than 5 MHz maximal clock frequency include the 8088-2, which was fabricated using Intel’s new enhanced nMOS process called HMOS and specified for a maximal frequency of 8 MHz. Later followed the 80C88, a fully static CHMOS design, which could operate with clock speeds from 0 to 8 MHz. There were also several other, more or less similar, variants from other manufacturers.

8088, designed and manufactured by NEC. Successive NEC 8088 compatible processors would run at up to 16 MHz. In 1984, Commodore International signed a deal to manufacture the 8088 for use in a licensed Dynalogic Hyperion clone, in a move that was regarded as signaling a major new direction for the company.

The 8088 is architecturally very similar to the 8086. The main difference is that there are only 8 data lines instead of the 8086’s 16 lines. All of the other pins of the device perform the same function as they do with the 8086 with two exceptions. The reason for the reversal is that it makes the 8088 compatible with the 8085.