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Now I spend some mental energy considering the controversial
topic of shifting. I want a fast barrel shifter, that will be
able to shift by any number of bits. This must be done in stages,
but using what TTL chips? To try to work out the best
configuration, I consider designs including
cascaded stages consisting of a number of the following TTL chips:
o 74LS151: Single 8-1 line multiplexer
o 74LS153: Dual 4-1 line multiplexer
o 74LS157: Quad 2-1 line multiplexer
