Simulates the pen function within 250 bytes (which I'm sure could be optimized more, if anyone wants to). The way I designed the program assumes that you have 94 as your xmax and 62 as your ymax, but you could probably change that easily. Even though this may not be of much use, it does make it simpler to erase pxls.
Arrow Keys: Move your pen
MODE: Switch between draw and erase mode
CLEAR: Stop Program
:47->X:31->Y:0->C //C represents whether you are in draw or erase mode :While 1 :getKey->K :Pxl-On(Y-1,X //the pxls represent your cursor :Pxl-On(Y,X-1 :Pxl-On(Y,X+1 :Pxl-On(Y+1,X :If K or C=1 :Then :Pxl-Off(Y-1,X :Pxl-Off(Y,X-1 :Pxl-Off(Y,X+1 :Pxl-Off(Y+1,X :End :If C=1:RecallPic 1 :X-(K=24)(X>1)+(K=26)(X<94)->X :Y-(K=25)(Y>1)+(K=34)(Y<94)->Y :If K=22 :not(C)->C :If C=1:Then :Text(1,1,"pxl-on //1 space :Pxl-On(Y,X :StorePic 1:End :If C=0:Then :Text(1,1,"pxl-off //no space. This text is optional, just to show which mode you are in. :Pxl-Off(Y,X :End :If K=45:Stop :End:End