Motorola 68000 - Page 41

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The 68000's Instruction Set
Condition codes: X N Z V C
- * * 0 0
MULS, MULU Signed multiply, unsigned
multiply
Operation: [destination] ← [destination] * [source]
Syntax: MULS <ea>,Dn
MULU <ea>,Dn
Attributes: Size = word (the product is a longword)
Description: Multiply the 16-bit destination operand by the 16-bit source
operand and store the result in the destination. Both the source
and destination are 16-bit word values and the destination result
is a 32-bit longword. The product is therefore a correct product
and is not truncated. MULU performs multiplication with unsigned
values and MULS performs multiplication with twos complement
values.
Application: MULU D1,D2 multiplies the low-order words of data registers D1
and D2 and puts the 32-bit result in D2. MULU #$1234,D3 multi-
plies the low-order word of D3 by the 16-bit literal $1234 and
puts the 32-bit result in D3.
Condition codes: X N Z V C
- * * 0 0
Source operand addressing modes
NBCD Negate decimal with sign extend
Operation: [destination]
10
← 0 − [destination]
10
- [X]
Syntax: NBCD <ea>