Page 2 LEVEL7 Non-Maskable Interrupt Debugger
Rev. B02
INSTALLING LEVEL7
Place the files LEVEL7.SYS and GOL7.LIT in DSK0:[1,4] and all overlays (*.L7O) in DSK0:[7,0]. The
source files are needed only if you plan on creating your own overlays. You may install them anywhere;
DSK0:[7,7] is normally a good choice.
In your system initialization file (always edit a copy of the file, not the original), locate the SYSTEM
statements. Before the final SYSTEM statement, add this statement:
SYSTEM LEVEL7.SYS/N{/E}{/T}{/P} {overlay} {overlay} {. . .}
/E is an optional switch which causes the normal exception vectors to be trapped. This means LEVEL7
will be invoked for such things as illegal instructions or address errors.
/T is the same as /E, except that it allows you to toggle exception vector trapping by using the GOL7
command (see below). This lets you enable and disable exception trapping without rebooting your
computer.
You can use /P with /E or /T to ignore privilege violations. These errors often occur due to differences in
newer CPUs from the original Motorola 68000. Normally AMOS handles them for you; however, the /E
or /T switch can cause LEVEL7 to trigger on them.
Each overlay is an optional overlay file to load. Though they are not required, most are very useful. For
example, the overlay JCB.L7O is available for displaying job control block information.
The proper SYSTEM statement, with all of the currently available overlays and exception trapping
enabled, but privilege violations ignored, would look like this:
SYSTEM LEVEL7.SYS/N/E/P JCB TCB DDB MAP SMEM DISASM IDENT
Once you reboot your system, the debugger should be ready. LEVEL7 will be invoked in any of three
circumstances:
•
If you press a button wired to the CPU UPS port, simulating a power fail condition.
•
If you use /E or /T, on any of the normal exception vectors.
•
If you didn’t use /T, when you enter the GOL7 command. This is handy for verifying the
debugger is properly installed.
If you use the /T switch, GOL7 does not enter LEVEL7. Instead, it toggles exception trapping. Exception
trapping is off when the system boots: the first use of GOL7 turns it on, the next turns it off, etc.
LEVEL7 MAIN MENU
The LEVEL7 debugger operates at interrupt level with interrupts locked. No other processing occurs
while you are in the debugger. When the debugger is activated through a power fail interrupt, processor
exception, or the GOL7 command, the diagnostic panel displays a “7” and the following menu appears
on the terminal attached to CPU port #0. The activated by line appears only when LEVEL7 is entered
due to an exception:
(13 pages)
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