sqrt.rpn

CONST R1 81 	; 16 = A
CONST R0 0  	; Initialize B to 0
PUSH R1
JSR SQRT
PRINTNUM
JSR END

LABEL SQRT
POP R5  		; Put the return PC value in R5
LABEL LOOP
PUSH R0
PUSH R0
MPY
POP R2  		; C = B * B
PUSH R1 
PUSH R2
SUB     		; B^2 - A
POP R3
BRANCHp R3 FINISH
CONST R4 1
PUSH R4
PUSH R0
ADD
POP R0
BRANCHnzp R0 LOOP

LABEL FINISH
PUSH R4
PUSH R0
SUB
JMPR R5

LABEL END