(hold down BACKSPACE and press the indicated key):
BACKSPACE, A -- Add players to AutoMap
BACKSPACE, B -- Border color
BACKSPACE, C -- Statistics
BACKSPACE, D -- Invisibility
BACKSPACE, E -- Jumps ahead to end of next level
BACKSPACE, F -- Displays x and y coordinates and angle
BACKSPACE, G -- God mode on/off (when ON you cannot be hurt)
BACKSPACE, H -- Hurt yourself (minus 1% health)
BACKSPACE, I -- Free items
BACKSPACE, M -- Displays memory usage
BACKSPACE, O -- Show all hidden walls on automap
BACKSPACE, Q -- Quit to DOS
BACKSPACE, S -- Slow motion on/off
BACKSPACE, T -- Displays walls, sprites, and sound waveforms.
BACKSPACE, U -- Unlock all floors
BACKSPACE, V -- ??? "Add extra VBLs(0-8)". Not sure what this does.
BACKSPACE, W -- Warp to any level