Originally Posted by TwoCables
Firmware? I've been on OCN for over 4 years and I have never heard of a CPU having firmware. What exactly are you talking about?
Well I'm new to OCN and I'm always happy to educate people!
As I remember from my college days—far more exciting and fun than the current boring ones, BTW—microprograms are the algorithms used inside the CPU. They are implemented in hardware, but there's still executable programs in there anyway, and even an area reserved for patch code.
Okay, I just looked it up in Wikipedia:
Microcode is a layer of hardware-level instructions and data structures that implement higher-level machine code instructions in central processing units. It resides in special high-speed [meaning register-speed] memory and translates machine instructions into sequences of detailed circuit-level operations. It helps separate the machine instructions from the underlying electronics so that instructions can be designed and altered freely. It also makes feasible complex multi-step instructions while reducing the complexity of the circuitry, compared to other methods.
I remember that in my beloved Univac mainframe, every memory fetch ("major cycle") was slow enough for eight "minor cycles" inside the CPU, and complex instructions were were written in microcode that took 8 or 16 minor cycles to complete. It's the lowest possible level of computer programming, even closer to the metal than assembler (which is really the only way to do it and say you're programming a computer instead of a virtual machine implemented as a language).
How it gets updated, from Tom's:
What is a 'microcode update'? Well, all [modern CPUs] have a little area that can store some software to deal with processor bugs right inside the CPU. Usually the motherboard BIOS loads this software into the processor right after boot-up. Each time Intel finds a new bug they try to create a new little software patch that is called a 'microcode update'.
Also BTW, microcoding has been around for decades, and AMD does it too. You get the new one with a BIOS update for the mom board.
-faye kane ♀ girl brain
sexiest astrophysicist you'll ever see naked
Edited by FayeKane - 6/26/13 at 12:10am