Testing Memory Accesses With The Background Monitor - HP HP8648A Instruction Manual

Chapter 4: Connecting the Emulator to a Target System
Installing Emulator Features
If you get the "?>" prompt or something other than the "M>" prompt, this indicates
something went wrong with monitor operation. This may indicate problems with
the clock or reset signals. Because the emulator provides all control signals for the
background monitor, typically problems are with signals that can prevent the
processor from running bus cycles.
Testing memory accesses with the background
monitor
Once the background monitor looks like it is running properly, you can use it to test
accesses to different ranges of memory in your target system. This may be an
easier way to diagnose problems than by running a program that accesses each
memory range. It is also easy to check accesses of different sizes using the monitor.
mo -aw -dl
m 0badad=12345678
When accesses to your target memory do not execute exactly right, the monitor
attempts to diagnose these problems and resolve them so the monitor program does
not malfunction. However, the monitor does not read back write cycles to check
the integrity of the data written. When testing memory accesses, you must check
the data to make sure it is correct.
M>m 0badad
If your target memory does not respond to a bus cycle, the monitor will force
termination of the cycle and report this error message:
!ERROR
78
4 Execute the command: rst -m. This tells the emulator to release reset, but
enter the monitor.
5 Verify that the emulator is in the monitor.
The prompt should be "M>", indicating that operation is in the monitor. There
is not much that can go wrong up to this point because everything required has
already been verified.
0000badad ffdf00ff
700! Target memory access failed