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PREPARATION FOR USE
Within the selected 256k page, you can select any 32k boundary to be the
ending Multibus address (of the dual port RAM); that is, you can select
one of 8 possible 32k boundaries within the 256k page at which to end
your Multibus address sequence.
Jumpers E230 through E233 and E240
through E243 provide the selection as listed in Table 2-10.
Ensure that
your address selection allows access to all useable memory locations; the
Multibus address cannot be incremented across a 256k page boundary.
Figure 2-5 provides an ~ddress configuration example for the iSBC 86/30
board that places 96k bytes of dual port RAM into Hultibus addresses
6FFFFH through 58000H.
Table 2-9.
256k Page Selection for iSBC® 86/30 Board
Jumpers
Installed
256k Page
E225-Gnd
E226-Gnd
E227-Gnd
Address Range
-
-
not used
000000-3FFFFH
-
X
not used
040000-7FFFFH
X
-
not used
080000-BFFFFH
X
X
not used
OCOOOO-FFFFFH
Table 2-10.
32k Ending Boundary Select for iSBC® 86/30 Board
Jumpers Installed
32k Ending Boundary
E232-E233
E230-E231
E240-E241
E242-E243
Offset in 256k Page
-
-
-
not used
03FFFFH
-
-
X
not used
037FFFH
-
X
-
not used
02FFFFH
-
X
X
not used
027FFFH
X
-
-
not used
01FFFFH
X
-
X
not used
017FFFH
X
X
-
not used
OOFFFFH
X
X
X
not used
007FFFH
NOTES: Multibus address (of dual port RAM)
=
(Megabyte Address Select)
+
(256k Page Select)
+
(32k Ending boundary Select).
X
=
Jumper installed.
Change 1
2-27
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