Selection register (S)

The Selection register (S) holds the current memory page number (5 bits) and currently selected channel number (4 bits). The remaining 3 bits are not used and always read zero.

bit   designation   descript
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0     c0            channel number
1     c1            ...
2     c2            ...
3     c3            ...
4     p0            memory page
5     p1            ...
6     p2            ...
7     p3            ...
8     p4            ...
9     0             not used
10    0             not used
11    0             not used
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