In message
<372d84e1-8cec-47fa-bea5-70dd0dd7a401@y21g2000hsf..com>, at
05:47:38 on Wed, 16 Jul 2008,
thagor2008@ remarked:
>From wikipedia:
>
>"A control store is the part of a CPU's control unit that stores the
>CPU's microprogram"
>
>"A control store is usually implemented as a diode-array of read-only
>memory"
I'm a fan of Wikipedia, but that stuff is just gibberish.
>So I guess at that level you could put forward a valid argument for it
>being hard wired diodes, or software in the sense of the way the
>diodes are wired. Or both! But then again I suppose you could say the
>same about any read only ROM.
There any many technologies that can be used to implement a ROM,
including the presence and absence of diodes in a matrix, and even the
ability to erase or restore such diodes in the field. This is
ludicrously technology-specific, however, and who is to say what a
generic CPU uses to store its microcode. (If you had asked me yesterday,
I might have said "the presence of absence of conductors between logic
gates").
--
Roland Perry