HP 64783A, Руководство пользователя

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If your target system does not use the TTRs, then you may want to modify
your MMU boot code to configure an instruction and data TTR specifically for
the monitor.
Example
This example shows how to modify boot code to use a pair of TTRs. Assume
your target system does not access any physical addresses in the 16-Mbyte
range 02000000..02ffffffh, and DTT0/ITT0 are unused. By locating the
monitor at address 02000000 and adding the following code fragment to your
boot code, you should be able to break into the monitor while the MMU is
turned on:
* configure ITT0/DTT0 for emulation monitor
MOVE.L #$0200C000,D0
MOVEC D0,ITT0
MOVEC D0,DTT0
Without these transparent translations for the monitor, the MMU will probably
generate an access fault when you attempt to break into the monitor. The
access fault would occur because addresses in the 02000000 range would have
no valid translations (they would be on a non-resident page).
If you cannot modify your boot code, you may be able to use an execution
breakpoint to break into the monitor before the MMU is enabled and use the
monitor to configure the TTRs. Do this only as a last resort because the
MC68040 processor automatically disables all TTRs whenever an emulation or
target reset occurs (and they must be reinitialized each time).
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The second way to provide proper address translation for the foreground
monitor is to locate the monitor within a page that is controlled by the MMU
address translation tables; one that is always resident, writeable, supervisor
accessible, and translated 1:1. The monitor occupies one 4-Kbyte page of
emulation memory. It will be stored in the 4-Kbyte range of the dual-port
memory.
Chapter 8: Configuring the Emulator
Providing MMU Address Translation for the Foreground Monitor
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