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The Base Address When reading or writing to a multiplexer register, specify a hexadecimal or
decimal register address. This address consists of a base address plus a
register offset. The base address used programming depends on whether the
A16 address space is outside or inside the HP E1405A/E1406A Command
Module or HP E1300A/E1301A Mainframe.
A16 Address Space
Outside the
Command Module
or Mainframe
When the command module or mainframe is not part of your VXIbus
system (Figure B-1), the multiplexer’s base address is computed as:*
C000
16
+ (LADDR * 64)
16
or
49,152 + (LADDR * 64)
where C000
16
(49,152) is the starting location of the register addresses,
LADDR is the multiplexer’s logical address, and 64 is the number of
address bytes per VXIbus device. For example, the multiplexer’s factory
set logical address is 112. With this address, the multiplexer has a base
address:
C000
16
+ (112 * 64)
16
C000
16
+ 1C00
16
= DC00
16
or (decimal)
49,152 + (112 * 64)
49,152 + 7,168 = 56,320
A16 Address Space
Inside the
Command Module
or Mainframe
When the A16 address space is inside the command module or mainframe
(Figure B-2), the multiplexer’s base address is computed as:
1FC000
16
+ (LADDR * 64)
16
or
2,080,768 + (LADDR * 64)
where 1FC000
16
(2,080,768) is the starting location of the VXI A16
addresses, LADDR is the multiplexer’s logical address, and 64 is the
number of address bytes per register-based device. Again, the multiplexer’s
factory set logical address is 112. If this address is not changed, the
multiplexer will have a base address of:
1FC000
16
+ (112 * 64)
16
1FC000
16
+ 1C00
16
= 1FDC00
16
or
2,080,768 + (112 * 64)
2,080,768 + 7,168 = 2,087,936
* The "16" at the end of the address indicates a hexadecimal number.
Appendix B HP E1351A/53A Register-Based Programming 83