Installing PC/Xi Boards
11
Please note that even though there are seven supported addresses below 1
megabyte, 0C0000h and 0D0000h are the only ones commonly available, and
that a 128K board will take up the entire area from 0C0000h to 0DFFFFh. This
can conflict with other peripherals such as ESDI and SCSI controllers, and EGA
or VGA video adapters. 128K boards can be reduced to 64K by changing the
positions of jumpers on the board. See the Appendix, starting on page 68, for
information on resolving memory conflicts.
For technical reference, switches 1-8 of DS1 are decoded as follows:
Address Bit
A1 6
A1 7
A1 8
A1 9
A2 0
A2 1
A2 2
A2 3
Switch (DS1)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
SW 7
SW 8
An address bit is decoded as a binary 1 if the corresponding switch is turned
OFF (or OPEN), and as a binary 0 if the switch is ON (or CLOSED). Address
bits A00-A15 are always decoded as 0, since DS1 only resolves 64K blocks of
memory.
