[Novalug] OT Computer organization vs architecture vs C vs assembler

Walt Smith waltechmail@yahoo.com
Tue Mar 30 15:59:07 EDT 2010


and Bryan quote-ethy:

>As far as 8-bit and virtual memory, it has nothing to do with 8-bit.
>In fact, you do _not_ need hardware to do virtual memory.  You're
>confusing the concepts of a hardware Memory Management Unit (MMU)
>with bit-size, let alone ignoring the option of software MMUs -- let
>alone different types of MMUs (I/O, etc...).


uh, no, I'm not  confused at all.  

However, I find your wanting to mix hardware function interesting
and creative.  Certainly there are today many "exceptions"
to many former rules.   But if we're talking instruction
to students, I'm not gonna say some 8 bit CPU has a MMU without
darn good reason ( if ever, and likely never ).

I can certainly graft a MMU onto a 6800 (I don't mean 68000 ).
Practical ?  probably not.  Instructive? Probably not.
I might even want to pretend some register is a lookup
method ( of addresses).  But unlikely.  Besides, there's no violation
protection ! ... or IS there ?  What happens when the address isn't
"present" ?   hmmm, is the existence of a mapping register "hardware" ? 


Walt....



      



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