HP E1563A, User Manual, Page: 115 / 166

HP E1563A and E1564A Register-Based Programming 115 Appendix B
A16 Address Space
Inside the Command
Module or Mainframe
When the A16 address space is inside the HP E1406A Command Module
(Figure B-2), the digitizer’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 digitizer’s logical address, and 64 is the number of
address bytes per register-based device. Again, the digitizer’s factory set
logical address is 40. If this address is not changed, the digitizer will have a
base address of:
1FC000
16
+ (40 * 64)
16
= 1FC000
16
+ A00
16
= 1FCA00
16
or
2,080,768 + (40 * 64) = 2,080,768 + 2560 = 2,083,328
Register Offset
The register offset is the register’s location in the block of 64 address bytes.
For example, the multiplexer’s Status/Control Register has an offset of 04
16
.
When you write a command to this register, the offset is added to the base
address to form the register address:
CA00
16
+ 04
16
= CA04
16
1FCA00
16
+ 04
16
= 1FCA04
16
Figure B-2. Registers within Command Module’s A16 Address Space