- The Intel 8086 processor (1978) has a complicated instruction set with instructions ranging from one to six bytes long. This raises the question of how the processor knows the length of an instruction.1 The answer is that the 8086 uses an interesting combination of lookup ROMs and microcode to determine how many bytes to use for an instruction. In brief, the ROMs perform enough decoding to figure out if it needs one byte or two. After that, the microcode simply consumes instruction bytes as it needs them. Thus, nothing in the chip explicitly “knows” the length of an instruction. This blog post describes this process in more detail.
instruction length decoding of
- Local Bubble (Wikipedia)
The Local Bubble, or Local Cavity, is a relative cavity in the interstellar medium (ISM) of the Orion Arm in the Milky Way. It contains the closest of celestial neighbours and among others, the Local Interstellar Cloud (which contains the Solar System), the neighbouring G-Cloud, the Ursa Major moving group (the closest stellar moving group) and the Hyades (the nearest open cluster).