Chroma CPU

[KA4HJH]

>batzman at all-electric.com wrote:
>> [...]
>> but motorola announced their intentions for a 16 bit processor
>> (68K) and intel quickly decided to shift focus mid stream. Thus
>> the 64K window and memory segmenting. Often euphemistically
>> referred to as "memory Management."

BTW, the 680x0 is a 32 bit processor. I've often seen this mis-reported,
even in major publications. One big-name PC mag said that the 68000 was 16
bit and that the others were 32. Of course, magazines don't write articles,
people do.

>I believe this was just a tradeoff between address range and the
>average instruction size.  In the 68K instruction set, addresses
>add 4 bytes to an instruction (but you can address 4GB).  With
>the 8086/88, addresses add 2 bytes but you can only address 64K
>without changing a segment register.  You could use the 68000's
>base+offset address mode to accomplish the same thing, but most
>68000 code I've seen just uses 32-bit addresses.  At least with
>the 68000 you get to choose whether to use "memory management".

That's why the Mac is was/is such a memory hog. Another (approximate) quote
"128K is enough for most users". Guess what famous computer mogul said
that? (it wasn't Bill Gates--the fool was talking about a computer with a
32 bit processor).

It's a good thing they didn't make it a fundamental limitation, like 640K.
That really would suck.  8-)

Terry Bowman, KA4HJH
"The Mac Doctor"