Forth Language Summary

                          top   
+         3 5 +            8
-         9 2 -            7
*         4 5 *            20
/         20 4 /           5
MOD       11 3 MOD         2
/MOD      11 3 /MOD        3 2        remainder, then quotient

HEX                                   (sets the mode)
DECIMAL
BASE      7 BASE !                    (BASE is special variable)

DUP       3 DUP            3 3        duplicates top
SWAP      1 2 3 4 SWAP     3 4 2 1    swaps top two
DROP      1 2 3 4 DROP     3 2 1      pops top
OVER      1 2 3 4 OVER     3 4 3 2 1  DUPs the second from top
ROT       1 2 3 4 ROT      2 4 3 1    rotates 3rd up to top
?DUP      1 2 3 0 ?DUP     4 3 2 1    DUP only if top is not 0
DEPTH     3 3 3 3 DEPTH    3 3 3 3 4  depth of stack

ABS       -4 ABS           4
MAX       3 6 MAX          6
MIN       3 6 MIN          3
MINUS     13 MINUS         -13

CONSTANT  6 CONSTANT SIX              SIX can be used for 6
VARIABLE  VARIABLE X                  X is declared a variable
!         25 X !                      X = 25
+!        4 X +!                      X = X + 4
@         X @              29         retrieves value of X

: ;       : SQR DUP * ;               defines procedure SQR
.         1 2 3 4 .        3 2 1      pops and PRINTS top to screen
.R        13 5 .R                     PRINTS the 13 right justified 5 columns
CR                                    carriage return
."        ." Howdy"                   PRINTS Howdy to screen

<         3 5 <            1          1: true  0: false
>         3 5 >            0
=         3 5 =            0
0<        -4 0<            1          negative
0>        -4 0>            0
0=        -4 0=            0

AND       13 11 AND        9          1101 AND 1011 = 1001
OR        13 11 OR         15         1101 OR 1011 = 1111
XOR       13 11 XOR        6          1101 XOR 1011 = 110
NOT       -2 NOT           1          ...1110 NOT --> ...0001

DO LOOP   5 2 DO ." hi" LOOP          hi hi hi  (5 is limit, 2 is start)
+LOOP     5 2 DO ." hi" 2 +LOOP       hi hi     (count by 2)
I         5 2 DO I . LOOP             2 3 4     (retrieve counter to stack)
IF        3 5 < IF ." hi" THEN        hi        (if 3 < 5 then print hi)
IF ELSE   3 5 < IF ." hi"
                ELSE ." no" THEN      hi (if 3 < 5 then hi else no)
WHILE     1 BEGIN DUP 20 < WHILE
                . 2 + REPEAT          BEGIN test WHILE loop-stuff REPEAT
UNTIL                                 BEGIN loop-stuff test UNTIL