HP 64783A, User Manual

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the next available stack location. Therefore, the exit stack starts four words below
the initial stack pointer.
ISP-8 - Status register = 2700
ISP-6 - Program Counter = 0000000a
ISP-2 - Vector Offset = 007C
The monitor is always exited using the FOUR WORD STACK frame, and the
monitor always uses 07C as the vector offset. When running a program from the
monitor after entering from reset, the powerup status word of 2700 is used.
Therefore, the only difference you will see in this stack frame will be because of
different initial program counters.
The procedure for setting the initial stack pointer and initial program counter can be
automated by using the initial vectors configuration question to define these values.
cf rv=<initial ISP>,<target program starting address>
Once this configuration has been set up, the following reset sequence may be useful
on systems that remap memory to provide reset vectors.
rst -m
r
Breaking into the foreground monitor
The next thing to try with the foreground monitor is to see if you can break into it
from your target program. The emulator uses a nonmaskable interrupt (interrupt 7)
to break into the monitor. The interrupt is generated in such a way as to not
interfere with any interrupts pending in your target system. The resulting interrupt
acknowledge cycle is not shown to the target system. The associated stacking is in
foreground memory at the location determined by the interrupt stack pointer. If the
target system program is running in Master mode, there will also be stacking on the
master stack.
A vector fetch occurs sometime during or after stacking. The emulator provides the
data for this vector fetch to correctly run the foreground monitor. While the
emulator is transitioning into the foreground monitor, interrupts are temporarily
blocked. Once in the monitor the interrupt mask level is lowered to the greater of
the "monint" configuration setting or the target program mask level.
Chapter 18: Connecting the Emulator to a Target System
Installing Emulator Features
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