[Simh] C64 and C128

[Clem Cole]

On Tue, Jun 30, 2015 at 9:48 PM, Rich Alderson <
simh at alderson.users.panix.com> wrote:

> Bit-addressed computers represent characters as sequences of bits (the term
> ​ ​
> "byte" originally meant "sequence of bits representing a character", not
> just
> ​ ​
> "eight bits").
>


​One of my favorite stories from an old friend (Russ Robelen) who was there
at the time [Russ lead the HW development of 360/50], was that Gene Amdahl
originally wanted the 360 architecture to use a 6 bit byte (and keep the
word size @ 24 bits).  Russ says Fred Brook's told Amdahl that unless it
was a power of two, it would be too difficult for the programmers.   Amdahl
thought it was a waste of resources, but those crazy SW guys won the war
and it used an 8 bit byte and 32 bit word.  Plus as you pointed out, was
byte addresses.   It's interesting that the 360 architecture lasted so long.

Gordon Bell used to say to small address size is the #1 reason why
architectures die.  I agree but I amend it to state, they also need
architecture features such as addressing modes, word size etc that are
powers of 2 and linear in expression/used (i.e. funky word size and
segments are losing ideas and will ultimately kill you).

Clem
​
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