[Coco] CoCo 3 MMU test for all

[Mark Marlette]

Robert/Roger,

See when Robert explains it in hex, you hardly even have to think about it.

Curtis did the same and they are correct and EASY to read and think about.

Take their advise and mine, switch to hex. You'll have a much better 
chance of retaining this because it will make sense.

Mark
Cloud-9

At 1/20/2008 08:53 PM, you wrote:

>Roger Taylor wrote:
>
>><snip>
>>You say $0-$f is for a 128k CoCo, so why are blocks 48-63 used 
>>within BASIC?   56-63 are stored in the TASK 0 64k map.
> ><snip>
>
>That is done so the ROM works with both 128K and 512K in a 
>transparent fashion. With less memory (128K) only bits values $0-$F are active.
>
>You could save that with 128K memory starts at $00000 and ends at 
>$20000. But then with 512K, the ROMs would "relocate". Things look 
>more consistent if you start 128K at $60000 even if that isn't 
>physically possible.
>
>If you think in $hex or better yet %binary, things might make more sense.
>$38-$3F are the default values but in binary are
>%00111000, %00111001, ... $00111111
>With 128K you actually use $0-$F.
>
>Why not use $0-$F in the ROM tables? If that were done, then any 
>memory used for the high res text or graphic screens would not be in 
>the same location relative to the ROMs going from 128K to 512K. 
>Would it matter? Probably not except from an aesthetic view point.
>===============
>Yes Roger, my hair is indeed getting thin. :)
>
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