Tcl commands to interface to DOS 

$Id$

kbhit - returns 1 if a key has been hit, else 0

getkey - returns a key as an integer keycode.  waits until a key
has been pressed.  (So use kbhit to see if one is there first, if you
don't want to wait.)

sound - start the sound playing a square wave at the specified
frequency in hertz.  If 0, stops the sound from playing.

getdate - returns the current date as a list containing month, day, year.

setdate month day year -- set the current date to the specified
month, day and year.

drive -- set the drive to the specified drive letter.

Example:  drive A

If drive letter is not specified, the current drive is returned.

memfree - returns the amount of RAM left on the system.

stackfree - returns the amount of stack left on the system

rawclock - returns the raw clock value in ticks since the time the program
started.

cls - clear the screen

heapcheck - check the heap for corruption.  If corruption is detected, the
program panics, printing an error message and then exiting immediately.

mkdir dir - create a directory.