[Coco] Re: Coco Repack

KnudsenMJ at aol.com KnudsenMJ at aol.com
Sat Aug 7 22:36:28 EDT 2004


In a message dated 8/7/04 10:09:18 PM Eastern Daylight Time, 
kevdig at hypersurf.com writes:

>   Forgive my stupidity, but why does reallocating the bits in the
>  address cut the max memory to 1 Meg (from 2?)?

Let's assume you restrict the MMU registers to 8 bits, so process DAT images 
can be stored in one byte per segment.  8 bits means 256 total RAM segments, 
no more!

Currently those are 8K apiece, times 256 = 2 Megs.
Many of us once longer for smaller segments, like 4K, but times 256 is only 1 
Meg total.

It's a tradeoff between total RAM size and segment sizes.  After a lot of 
public head bashing against the walls, some years ago we concluded that Tandy's 
original design of 8K wasn't so bad after all.

Besides, it's what the DEC PDP-11 family used -- the machines where UNIX was 
nurtured, if not born.  --Mike K.



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