Xycom XVME 200 Manual page 30

XVME-200/290 Manual
December, 1987
A specific register address in one of the 68230 chips can be accessed by simply
adding the specific register offset to the module base address.
offset specified for the Port General Control Register for PI/T #2 is 41H, and if
the module base address is jumpered to 1000H,
1041H.
Module Base Address
1000H
The XVME-200/290 are an odd byte only slave, and
as such, the module will not respond to even
address,
accesses may be used, with the understanding that
only the odd byte of the word is used to exchange
data.
listed in Table 3-l would all be decremented by 1.
Figure 3-l shows a simple map of the 1K block of the short I/O address space
which is occupied by the XVME-200/290 Modules.
Base + 00H
3EH
40H
7EH
80H
3FEH
Figure 3-1. Memory Map of the XVME-200 and XVME-290 Modules
Register Offset
41H
NOTE
single-byte accesses.
If word accesses are used, the register offsets
EVEN
U
N
U
S
E
D
Unused
3-3
For example, the
the register can be accessed at
PCG Register #2
=
1041H
However, word
ODD
0lH
3FH
41H
7FH
81H
3FFH