[Coco] CoCo 3 MMU test for all
operator at coco3.com
Sun Jan 20 20:06:24 EST 2008
At 03:49 PM 1/20/2008, you wrote:
>I haven't been following this that close because it is something I
>As james has indicated, basic CoCo understanding of the CoCo's
>internal registers. A stock MMU is only 6 bits wide. 'AND' off the
>upper two bits, bit6 & bit7.
>Go to a 1 meg machine and bit0-6 will be used.
>Go to a 2meg machine and bit0-7 will be used.
>256 blocks of 8k sized blocks = 2megs.
At least one of my comments were "sleep deprived" comments. ;) I've
written programs like P-3 that take advantage of the full 512k memory
map in a tricky way but using apparent blocks 0-63. If 64 is added
by the GIME for 128-512k CoCo's then I suppose it really means blocks
64-127 for 512k, and 112-127 for 128k even if you poke 0-63, while 1
meg upgrades *may* set the highest bit 7 by default to give the same
behavior to push the blocks upward in the same fashion?
If so, what is now apparent for the actual hardware block #'s
(regardless of what a PEEK reveals at the prompt for an MMU register
for 128k-512k CoCo's):
1 meg: 64-255
2 meg: 0-255
Somebody will correct me if I'm wrong, but this is what I'm
gathering. For a stock CoCo 3, blocks are referenced as 48-63, though.
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