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Chapter 4 Register Descriptions
© National Instruments Corporation 4-19 VXI-MXI User Manual
A24EN A24DIR Window Applies to
0 X Disabled
10
VXI cycles to MXI cycles
1 MXI cycles to VXI cycles
12-11r/w 1 Reserved Bits
These bits are reserved and read back as ones. Write a zero when
writing to these bits.
10-8r/w A24SIZE[2-0] A24 Window Size Bits
This 3-bit number specifies the number of significant address bits
in the A24BASE field that are compared when determining if an
address is in the A24 window. The number of A24 addresses in
the window is 65536 * 2
8-i
where i is the value of A24SIZE[2-0].
The minimum size of an A24 window is 128 KB, and the
maximum size is 16 MB.
7-0r/w A24BASE[7-0] A24 Window Base Address Bits
These bits, in conjunction with the A24SIZE bits, define the base
address of the A24 window for the VXI-MXI. The A24SIZE bits
indicate the number of A24BASE bits that are most significant.
A24BASE7 is the most significant and A24BASE0 is the least.
The A24BASE bits that are not significant can be replaced with
zeros to provide the base address of the A24 window.
A24 Window Example:
A24BASE A24SIZE A24 Addresses in Window
any value 0 000000 to FFFFFF
4E 1 000000 to 7FFFFF
A7 2 800000 to BFFFFF
35 3 200000 to 3FFFFF
6C 4 600000 to 6FFFFF
81 5 800000 to 87FFFF
B4 6 B40000 to B7FFFF
02 7 020000 to 03FFFF
00 0 000000 to FFFFFF
00 1 000000 to 7FFFFF
00 2 000000 to 3FFFFF
00 3 000000 to 1FFFFF
00 4 000000 to 0FFFFF
00 5 000000 to 07FFFF
00 6 000000 to 03FFFF
00 7 000000 to 01FFFF