Example Assembler

hillbilly1.php

@@ -88,8 +88,65 @@ WAIT    : 0c  00001100
 \       :
 </pre>
 
-<p> <a href="/hillbilly1/ADD16.asm">Here</a> is an example 16 bit adder program for the DAVIAC-1.</p>
-<p> The Assembler produces the <a href="/hillbilly1/ADD16.hex">Hex</a> and a <a href="/hillbilly1/ADD16.lst">run list</a>.
+	  <p> <a href="/hillbilly1/ADD16.asm">Here</a> is an example 16 bit adder program for the DAVIAC-1.</p>
+	  <pre>
+	    \	RAM Variables
+	ORG		0800H			\RAM at 0800h
+	DEF		X_Lo		*1
+	DEF		X_Hi		*1
+	DEF		Y_Lo		*1
+	DEF		Y_Hi		*1
+	DEF		Z_Lo		*1
+	DEF		Z_Hi		*1
+	DEF		Carry_Lo	*1
+	DEF		Carry_Hi	*1
+	ORG		0400h
+\
+\	load some numbers
+\
+\	Put numbers in X and Y at 0800H by hand from Control Panel.
+\
+\
+\	16bit ADD  X + Y -> Z + Carry_Hi
+\
+	
+\
+	NOP
+ADD16:
+	WAIT
+	STAZ	Carry_Lo		\Clear lo carry
+	LDAA	X_Lo
+	LDAB	Y_Lo
+	ADD						\ADD lo bytes
+	STAC	Z_Lo			\store partial sum
+	BRNO	ADD16J1:		\test OVF bit to see if Carry required
+	LDIA	01h				\must be OVF, set a Carry_Lo
+	STAA	Carry_Lo
+ADD16J1:
+	STAZ	Carry_Hi		\Clear hi carry
+	LDAA	X_Hi
+	LDAB	Y_Hi
+	ADD						\ADD hi bytes
+	STAC	Z_Hi			\store hi partial sum
+	BRNO	ADD16J2:
+	LDAA	01h				\might be a hi carry
+	STAA	Carry_Hi
+ADD16J2:	
+	MOVC,A
+	LDAB	Carry_Lo		\include any lo carry
+	ADD
+	STAC	Z_Hi
+	BRNO	ADD16J3:
+	LDAA	01h
+	STAA	Carry_Hi		\which may trigger a hi carry
+ADD16J3:	
+\
+	BRA		ADD16:
+\
+\	end of ADD16p
+	    </pre>
+
+	  <p> The Assembler produces the <a href="/hillbilly1/ADD16.hex">Hex</a> and a <a href="/hillbilly1/ADD16.lst">run list</a>.
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