The key that is called <DEL> in Emacs (because that's how it is designated on most workstations) is known as <BS> (backspace) on a PC. That is why the PC-specific terminal initialization remaps the <BS> key to act as <DEL>; the <Delete> key is remapped to act as C-d for the same reasons.
Emacs built for MS-DOS recognizes C-<Break> as a quit character, just like C-g. This is because Emacs cannot detect that you have typed C-g until it is ready for more input. As a consequence, you cannot use C-g to stop a running command (see Quitting). By contrast, C-<Break> is detected as soon as you type it (as C-g is on other systems), so it can be used to stop a running command and for emergency escape (see Emergency Escape).
The PC keyboard maps use the left <Alt> key as the <META> key.
You have two choices for emulating the <SUPER> and <HYPER> keys:
choose either the right <Ctrl> key or the right <Alt> key by
setting the variables dos-hyper-key and dos-super-key to 1
or 2 respectively. If neither dos-super-key nor
dos-hyper-key is 1, then by default the right <Alt> key is
also mapped to the <META> key. However, if the MS-DOS international
keyboard support program KEYB.COM is installed, Emacs will
not map the right <Alt> to <META>, since it is used for
accessing characters like ~ and @ on non-US keyboard
layouts; in this case, you may only use the left <Alt> as <META>
key.
The variable dos-keypad-mode is a flag variable that controls
what key codes are returned by keys in the numeric keypad. You can also
define the keypad <ENTER> key to act like C-j, by putting the
following line into your _emacs file:
;; Make the <ENTER> key from the numeric keypad act as C-j. (define-key function-key-map [kp-enter] [?\C-j])