Editing Data General Nova (section)

===16-bit multiplication===
Basic models of the Nova came without built-in hardware multiply and divide capability, to keep prices competitive. The following routine multiplies two 16-bit words to produce a 16-bit word result (overflow is ignored). It demonstrates combined use of ALU op, shift, and test (skip). Note that when this routine is called by <code>jsr</code>, AC3 holds the [[return address]]. This is used by the return instruction <code>jmp 0,3</code>. An idiomatic way to clear an accumulator is <code>sub 0,0</code>. Other single instructions can be arranged to load a specific set of useful constants (e.g. -2, -1, or +1).
<syntaxhighlight lang="nasm">
 mpy:	; multiply AC0 <- AC1 * AC2, by Toby Thain

 	sub 0,0		; clear result
 mbit:	movzr 1,1,szc	; shift multiplier, test lsb
 	add 2,0		; 1: add multiplicand
 	movzl 2,2,szr	; shift and test for zero
 	jmp mbit	; not zero, do another bit
 	jmp 0,3		; return
</syntaxhighlight>