68K System Monitor
User's Guide | GE Energy Services |
DB - Define Breakpoint
Platform
Description
Syntax
þ CPM þ D20 | o D20 ME | o D20/200 | þ D20/200 ME | þ D25 |
D20 Base | D20 Base | CCU Base | CCU Base |
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Use this command to activate a breakpoint in a section of code located within RAM.
At the specified address, the command saves 68000 family instruction in the breakpoint table and replaces it with a TRAP instruction. When a process reaches the TRAP instruction, it traps into a breakpoint handling routine, which displays a message indicating that it encountered a breakpoint.
The 68K Monitor allows up to ten active breakpoints.
Below is usage and syntax information for this command
Command Format | db address [#loops] | ||
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Variables | None |
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Parameters | address | = | hexadecimal address for the breakpoint. |
| #loops | = | number of times to execute the specified address |
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| (in decimal) before stopping; default is zero |
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| Example | Type db 103648 and press ENTER. |
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| This defines a breakpoint at hexadecimal address 103648, |
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| which stops before the first execution of the instruction at that |
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| address. |
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| Results: The system responds with the breakpoint number |
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| assigned to this breakpoint and the prompt. Each time |
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| it encounters the breakpoint, the system displays the |
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| breakpoint number, loop count, and register values. If |
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| the loop count is greater than zero, it is decremented. |
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| Otherwise, the process is suspended. |
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| Special | You may define only one breakpoint at a single address, to a |
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| Considerations | maximum of ten breakpoints per system. An attempt to define |
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| a breakpoint in read only or |
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| bus error. |
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General |
Full Release | |
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