- How the 8086 processor’s microcode engine works (righto.com)
The 8086 microprocessor was a groundbreaking processor introduced by Intel in 1978. It led to the x86 architecture that still dominates desktop and server computing. The 8086 chip uses microcode internally to implement its instruction set. I’ve been reverse-engineering the 8086 from die photos and this blog post discusses how the chip’s microcode engine operated. I’m not going to discuss the contents of the microcode1 or how the microcode controls the rest of the processor here. Instead, I’ll look at how the 8086 decides what microcode to run, steps through the microcode, handles jumps and calls inside the microcode, and physically stores the microcode. It was a challenge to fit the microcode onto the chip with 1978 technology, so Intel used many optimization techniques to reduce the size of the microcode.
- NGC 5286 (Wikipedia)
NGC 5286 (also known as Caldwell 84) is a globular cluster of stars located some 35,900 light years away in the constellation Centaurus. At this distance, the light from the cluster has undergone reddening from interstellar gas and dust equal to E(B – V) = 0.24 magnitude in the UBV photometric system. The cluster lies 4 arc-minutes north of the naked-eye star M Centauri. It was discovered by Scottish astronomer James Dunlop, active in Australia, and listed in his 1827 catalog.