
68
Rabbit 2000/3000 Microprocessor
Description
A multiplication operation is performed on the contents of the 16-bit binary integers contained in the BC and
DE registers. The signed 32-bit result is placed in the HL (bits 31 through 16) and BC (bits 15 through 0) reg-
isters.
If the multiplier is negative, the hardware takes its 2’s-complement as multiplication is being performed. If
the multiplier is positive, it is passed unchanged. If there is a carry from this stage of the 2’s complement
operation, it is passed to the next stage.
This instruction is implemented for the Rabbit and is not available for the Z180.
Examples:
LD BC, 0FFFFh
;BC gets -1
LD DE, 0FFFFh
;DE gets -1
MUL
;HL|BC = 1, HL gets 0000h, BC gets 0001h
In the above example, the 2’s complement of FFFFh is 0001h.
LD BC, 0FFFFh
;BC gets -1
LD DE, 00001h
;DE gets 1
MUL
;HL|BC = -1, HL gets FFFFh, BC gets FFFFh
MUL
Opcode
Instruction
Clocks
Operation
F7
MUL
12 (2,10)
HL:BC = BC • DE
Flags
ALTD
I/O
S
Z
L/V
C
F
R
SP
S
D
-
-
-
-
Summary of Contents for 2000
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