Reset Process

Go / Continue

Choosing Go / Continue will start the program executing from the location of the current PC. Execution will continue until
  • the program finishes
  • a break point or watch point is encountered
  • the program is interrupted using the Pause menu item.
  • an exception such as an illegal memory reference. While a program is "Going", the display windows, with the exception of the I/O window, are normally not updated. However, a special xfc #UPDATE_WINDOWS call exists to force an update of all windows (see the I/O section in the Appendix).

    Step-Step

    Step-Step executes one instruction at a time. It then updates the contents of all the windows, and continues with the next instruction. Step-Step can be interrupted using the Pause menu item.

    Step

    Step executes one instruction, updates all the windows, and then stops.

    Pause

    The Pause command allows you to interrupt MacVAX whilst it is executing your program. Pause will interrupt both the Go / Continue and Step-Step modes of operation.

    Toggle Watch / Break Points

    The Toggle Watch/Break Points command is used to set watch and break points in your program. To set a watch or break point, select a byte in the Memory Dump or Program window, and choose the Toggle Watch/Break Points command. A rectangle appears around the location in the window to indicate the break point. This may also be done under operating system control using xfc #SET_WATCHPOINTS.

    Clear All Watch Points

    Removes all set watch/break points. This may also be done under operating system control using xfc #CLEAR_WATCHPOINTS.

    Stop on Read
    Stop on Write

    These command toggles between enabling and disabling when watch/break points will cause a break in program execution. Turning Stop on Read on means that reads of watch and break points memory addresses will cause program execution to be interrupted. Turning Stop on Write on means that writes to watch and break points memory addresses will cause program execution to be interrupted. If both are disabled, MacVAX will continue execution as if no watch/break points are set. However, the simulator doesnŐt forget where these points were, and will restore them if you choose to enable either option again at a later time. MacVAX identifies watch and break points by drawing a rectangle around the locations in the Memory Dump and Program windows.

    Display Memory Usage

    Presents a dialog box with memory usage statistics.