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C.9 CPU32BUG QUESTIONS AND ANSWERS
Q: How can I change the chip selections to fit my application?
A: Use the Chip Select Table parameters to customize for your application. Note that there are
two tables; an Old one for Rev. A BCC units and a New one for Rev. B (and later) units. The
selection is based upon whether good RAM is obtained when chip select 0 and 1 are
programmed using the Old Table values. Consult Tables C-3 and C-4 for chip select
assignments. The chip selects designated for the BCC must not be altered, but the PFB chip
selects can be used if the corresponding resource is not used. Place your new values in the
correct table, or place them in both tables if you're not sure.
Q: How can I change CPU32Bug to automatically configure on-board MCU resources, such as
Standby RAM Module on the MC68332, upon power up?
A: Use the Initialization Table (INITTBL) to set up the address and data values to be written that
will initialize the desired resource. The following example shows how Initialization Table #2
can be used to initialize the 2K Standby RAM Module on the MC68332 to appear at address
$80000 in unrestricted space and assumes the register module base address is at $00FFF000
(MM bit in MCR register equals one). Remember. Initialization Table #1 is invoked before
the normal chip select initialization (via PWR_INI), while Initialization Table #2 is invoked
after the normal chip select initialization.
Offset
$D0
$D4
$D8
$D9
$DA
$DC
$E0
$E1
$E2
$E4
Q: How can I change CPU32Bug so I don't have to reprogram CPU32Bug's checksum every
time I change my user program in the second half of the BCC EPROM?
A: Change the CODESIZE parameter to $10000 so only the first half of the BCC EPROM is
used in calculating the checksum. Or, disable the checksum by setting it to the
unprogrammed state of all $FF's, i.e., set the CHECKSUM parameter to $FFFF.
M68CPU32BUG REV 1
Value
Table #1 termination value.
$FFFFFFFF
RAMMCR address.
$00FFFB00
Word sized write.
$02
Filler value to align word value.
$FF
Word value to be written to RAMMCR.
$0000
RAMBAR address.
$00FFFB04
Word sized write.
$02
Filler value to align word value.
$FF
Word value to be written to RAMBAR.
$0800
Table #2 termination value.
$FFFFFFFF
C-19
USER CUSTOMIZATION
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