Digital I/O•The microprocessor performs arithmetic operations, store data, communiicateswith the outside world, etc.CPUKeyboard Disk Drive I/OSerial/parallel/usb/ etcRAM(CMOS)memoryClock Power SupplyALUarithmeticROMprogramAddress BusDAQDataAquisitionMotherboard•Three state logic is important in microprocessor design so the many parts can be selectively addressed without affecting the other parts. •The unused devices on the address bus are plced in disable states anddo not respond to address bus signals.Binary Addition A B Carry Sum0 + 0 = 0 01 + 0 = 0 00 + 1 = 0 01 + 1 = 1 0 63 = 0 011111 1111111+5 = + 0000 010168 0100 010068! "# $#ABXORANDcarry bitsum• Binary addition closely follows the XOR function. A ! B = A " B + 1Two' sComplement!Binary Subtraction by Two's Complement 63 = 0011 1111!5 = + 1111 1011 " 0000 0101 + 158 1drop! 0011 101058" # $ % $ • Binary subtraction is most efficiently accomplished by Two's ComplementAddition.Chapter 13 pg 304Chapter 13 pg
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