- The Intel 8086 processor started the x86 architecture that is still extensively used today. The 8086 has some quirky characteristics: it is little-endian, has a parity flag, and uses explicit I/O instructions instead of just memory-mapped I/O. It has four 16-bit registers that can be split into 8-bit registers, but only one that can be used for memory indexing. Surprisingly, the reason for these characteristics and more is compatibility with a computer dating back before the creation of the microprocessor: the Datapoint 2200, a minicomputer with a processor built out of TTL chips. In this blog post, I’ll look in detail at how the Datapoint 2200 led to the architecture of Intel’s modern processors, step by step through the 8008, 8080, and 8086 processors.
