G33はBP2#ですが、
Intel Architecture Software Developer's Manual
Volume 3: System Programming
の、5-25 に、

Interrupt 3 - Breakpoint Exception (#BP)

Exception Class 　Trap.

Description
Indicates that a breakpoint instruction (INT 3) was executed, causing a breakpoint trap to be generated. Typically, a debugger sets a breakpoint by replacing the first opcode byte of an instruction with the opcode for the INT 3 instruction. (The INT 3 instruction is one byte long, which makes it easy to replace an opcode in a code segment in RAM with the breakpoint opcode.) The operating system or a debugging tool can use a data segment mapped to the same physical address space as the code segment to place an INT 3 instruction in places where it is desired to call the debugger.

With the P6 family, Pentium, Intel486, and Intel386 processors, it is more convenient to set breakpoints with the debug registers. (Refer to Section 15.3.2., “Breakpoint Exception (#BP) - Interrupt Vector 3”, in Chapter 15, Debugging and Performance Monitoring, for information about the breakpoint exception.) If more breakpoints are needed beyond what the debug registers allow, the INT 3 instruction can be used.

The breakpoint (#BP) exception can also be generated by executing the INT n instruction with an operand of 3. The action of this instruction (INT 3) is slightly different than that of the INT 3 instruction (refer to “INTn/INTO/INT3 - Call to Interrupt Procedure” in Chapter 3 of the Intel Architecture Software Developer’s Manual, Volume 2).

Exception Error Code
None.

Saved Instruction Pointer
Saved contents of CS and EIP registers point to the instruction following the INT 3 instruction.

Program State Change
Even though the EIP points to the instruction following the breakpoint instruction, the state of the program is essentially unchanged because the INT 3 instruction does not affect any register or memory locations. The debugger can thus resume the suspended program by replacing the INT 3 instruction that caused the breakpoint with the original opcode and decrementing the saved contents of the EIP register. Upon returning from the debugger, program execution resumes with the replaced instruction.

とあるので、プログラム開発をするとき、デバッグ時のブレークポイントを知らせるために使うようです。
ということで、通常は使うことはあまりないと思います。

ありがとうございました。ちょっと安心しました。

赤星です
すみません、便乗質問ですが、AJ31を折ると133MHzで認識するというのは、逆に言えばAJ31を折らないとFSBによるオーバークロックが出来ない、と言うことですか?
BIOSでFSBを133MHzに設定しても100MHzになってしまう???

＞ すみません、便乗質問ですが、AJ31を折ると133MHzで認識するというのは、逆に言えばAJ31を折らないとFSBによるオーバークロックが出来ない、と言うことですか?

可能かどうかはMBによって異なります。つまり、BSELピンの状態によって、設定できるFSBが制限されるMBと、BSELの状態によらずに自由にFSBを設定できるMBが存在します。