SYSBEEP is a read-write boolean system variable controlling whether system sounds are on or off (such as the sounds made by the 'keyboard').
Reading SYSBEEP always gives a result of 1 (TRUE), indicating the sounds are on, or 0 (FALSE), indicating the sounds are off. When writing a value to SYSBEEP, that value is rounded down, and if the result is 0, then SYSBEEP is set to FALSE, otherwise it is set to TRUE.