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Addition and Subtraction (足し算・引き算)



Unsigned base 2 adder: xm-1...x0 + ym-1...y0 + c0(see Figure 4.1)


  
Figure 4.1: An unsigned base 2 adder
\includegraphics[width=12cm]{/home/david/courses/comparch/lectures/arith/figs/usadder.eps}



2's Complement subtracter

\includegraphics[width=5cm]{/home/david/courses/comparch/lectures/arith/figs/2scompsub.eps}

2's Complement adder/subtracter

\includegraphics[width=14cm]{/home/david/courses/comparch/lectures/arith/figs/2scompas.eps}

Fast addition by carry lookahead (桁上げ先見)

8-bit carry lookahead adder


\includegraphics[width=15cm]{/home/david/courses/comparch/lectures/arith/figs/lookahead.eps}




next up previous contents
Next: Multiplication (掛け算) Up: Fixed-Point Arithmetic (固定小数点) Previous: Fixed-Point Arithmetic (固定小数点)
David Asano
2001-05-29