HDD Clicker generates HDD clicking sounds, based on HDD Led activity

Under MS-DOS such utilities existed and it was also used to demonstrate interrupt hooks in assembly tutorials. To do this, they'd:

- change INT 13h (the disk access routines in the BIOS) handler address

- write a handler that clicks the speaker or draws something to video memory without modifying any input registers

- pass the input over to the original handler which will complete the disk operation

- return or remove the return address of the inserted snippet from the stack and let the original handler do an IRET

The end result is e.g. an ASCII smiley face blinking in one of the corners of the screen in text mode or a similar style of crackling/screetching from the PC speaker.

Here is a full-featured example: https://github.com/MobyGamer/softhddi