Programmer's key

The programmer's key, or interrupt button, is a button or switch on Classic Mac OS-era Macintosh systems, which jumps to a machine code monitor.

The symbol on the button is ⎉: U+2389 ⎉ CIRCLED HORIZONTAL BAR WITH NOTCH.

On most 68000 family based Macintosh computers, an interrupt request can also be sent by holding down the command key and pressing the power key on the keyboard.

[1][2] Modern Mac hardware no longer includes the interrupt button, as the Mac OS X operating system has integrated debugging options.

In addition, Mac OS X's protected memory blocks direct patching of system memory (in order to better secure the system).

The interrupt button/programmer's key protruding from the air vent on the left-hand side of an Apple Macintosh Classic II computer (on the left, above the circular symbol)