For an old CPU, finding all the valid instructions wasn’t very hard. You simply tried them all. Sure, really old CPUs might make it hard to tell what the instruction did, but once CPUs got illegal ...

Video gamers know about cheat codes, but assembly language programmers are often in search of undocumented instructions. One way to find them is to map out all of a CPU’s opcodes and where there are ...

From chip-red-pill/uCodeDisasm: The microcode of the Intel Atom CPUs consists from two large chunks of data – Microcode Triads and Sequence Words. These data are ...

Ben Eater and others use an instruction processing sub-cycle where a given op code is executed as a sequence of microcode instructions. My thoughts (Aug 2019) on microcoded instructions such as those ...

Infosec boffins have released a tool to decrypt and unpack the microcode for a class of low-power Intel CPUs, opening up a way to look at how the chipmaker has implemented various security fixes and ...

My understanding was that a CPU microcode update is stored in non-volatile memory on the motherboard and is loaded by the BIOS or UEFI into volatile memory on the CPU during boot. And because the ...