B.4.123. `INT3', `INT1', `ICEBP', `INT01': Breakpoints
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INT1 ; F1 [P6]
ICEBP ; F1 [P6]
INT01 ; F1 [P6]
INT3 ; CC [8086]
INT03 ; CC [8086]
`INT1' and `INT3' are short one-byte forms of the instructions `INT
1' and `INT 3' (see *Note Section B.4.122::). They perform a similar
function to their longer counterparts, but take up less code space.
They are used as breakpoints by debuggers.
* `INT1', and its alternative synonyms `INT01' and `ICEBP', is an
instruction used by in-circuit emulators (ICEs). It is present,
though not documented, on some processors down to the 286, but is
only documented for the Pentium Pro. `INT3' is the instruction
normally used as a breakpoint by debuggers.
* `INT3', and its synonym `INT03', is not precisely equivalent to
`INT 3': the short form, since it is designed to be used as a
breakpoint, bypasses the normal `IOPL' checks in virtual-8086 mode,
and also does not go through interrupt redirection.