Technical data

2-12 Computer Group Literature Center Web Site

Startup and Operation

You will need to reset your system if the processor ever halts, or if the

172Bug environment is ever lost (vector table is destroyed, stack

corrupted, etc.).

Abort

Aborts are invoked by pressing and releasing the ABORT switch on the

MVME172LX front panel. When you invoke an abort while executing a

user program (running target code), a snapshot of the processor state is

stored in the target registers. This characteristic makes aborts most

appropriate for terminating user programs that are being debugged.

If a program gets caught in a loop, for instance, aborts should be used to

regain control. The target PC, register contents, etc., help to pinpoint the

malfunction.

Pressing and releasing the

ABORT switch generates a local board condition

which may interrupt the processor if enabled. The target registers,

reflecting the machine state at the time the

ABORT switch was pressed, are

displayed on the screen. Any breakpoints installed in your code are

removed and the breakpoint table remains intact. Control is returned to the

debugger.

Break

Pressing and releasing the <BREAK> key on the terminal keyboard

generates a "power break". Breaks do not produce interrupts. The only

time that breaks are recognized is while characters are being sent or

received by the console port. A break removes any breakpoints in your

code and keeps the breakpoint table intact. If the function was entered

using SYSCALL, Break also takes a snapshot of the machine state. This

machine state is then accessible to you for diagnostic purposes.

In many cases, you may wish to terminate a debugger command prior to

its completion (for example, during the display of a large block of

memory). Break allows you to terminate the command.