GE 68K System manual DB Define Breakpoint

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

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]
Variables	None
Parameters	address	=	hexadecimal address for the breakpoint.
	#loops	=	number of times to execute the specified address
			(in decimal) before stopping; default is zero

Example	Type db 103648 and press ENTER.
	This defines a breakpoint at hexadecimal address 103648,
	which stops before the first execution of the instruction at that
	address.
	Results: The system responds with the breakpoint number
	assigned to this breakpoint and the prompt. Each time
	it encounters the breakpoint, the system displays the
	breakpoint number, loop count, and register values. If
	the loop count is greater than zero, it is decremented.
	Otherwise, the process is suspended.
Special	You may define only one breakpoint at a single address, to a
Considerations	maximum of ten breakpoints per system. An attempt to define
	a breakpoint in read only or non-existent memory results in a
	bus error.

General SWM0023-1.00 -2

Full Release 3-21