8088

The Intel 8088 is an 8-bit microprocessor introduced in 1979. It is a variant of the 8086 with an 8-bit external data bus while retaining the 16-bit internal architecture. It uses a 20-bit address bus, enabling a maximum of 1 megabyte of addressable memory. The instruction set and registers are compatible with the 8086, including the segmented memory model with segment registers CS, DS, ES and SS, and the instruction pointer IP.

The processor core is organized into a bus interface unit (BIU) and an execution unit (EU). The 8-bit data path on the outside made the 8088 cheaper to implement and better aligned with existing 8-bit peripherals and memory, at the cost of performance relative to the 8086. Clock rates typically reach up to 5 MHz, with the IBM PC historically using a 4.77 MHz clock to match external timings.

Applications and impact: The 8088 became the central processor in the IBM PC and many compatible systems released in the early 1980s. Its combination of modest cost and 16-bit internal operations allowed DOS and early PC software to run efficiently, helping to establish a broad software ecosystem and a standard platform for personal computers.

Legacy: The 8088 is regarded as the first widely adopted member of the x86 family in personal computers, contributing to the long-term compatibility of x86 software. It was followed by faster members of the same family and by architectures that expanded the 16-bit and later 32-bit capabilities of the line.