Appeal No. 1996-3193
Application 08/160,112
The examiner relies on the following prior art
references:
Taniguchi 5,373,459 December
13, 1994
(filed April 17, 1992)
Hill, Fredrick J., and Peterson, Gerald R., Digital
Systems: Hardware Organization and Design 596-99(2d ed.,
John Wiley & Sons 1978)(hereinafter "Hill").
Taniguchi, figure 6, discloses a circuit whose function
"is to output the absolute value of the difference between the
inputted two data" (col. 14, lines 26-27). The value of (X-Y)
is formed in circuit 602 along with an overflow signal 609.
The value of {X-(Y+1)} is formed in circuit 603 and the
inverse {X&-&(&Y&+&1&)&} is formed in circuit 604, where {X&-&(&Y&+&1&)&}
= -(X-Y) = the two's complement of (X-Y) (col. 12, equations
14 and 15). If the overflow is 0, the result of the
subtraction (X-Y) is positive and the selection circuit 605
outputs the value of (X-Y), whereas if the overflow is 1, the
result of the subtraction (X-Y) is negative and the selection
circuit 605 outputs {X&-&(&Y&+&1&)&} = -(X-Y) (col. 12,
lines 51-57).
Hill describes multiplication with carry-save addition.
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