Computer Architecture and Organization: L02: Logic design Review By: A. H. Abdul Hafez Abdul.hafez@hku.edu.tr, ah.abdulhafez@gmail.com CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Outlines Combinational circuits Sequential circuits Gates Multiplexers Encoders/decoders D – Latches SR, JK flip flops Sequential circuits Registers Registers with parallel load Shift registers Serial communications Counters Binary counters BCD counters Synchronous counters CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Combinational Circuits: Gates The most elementary specification of the function of a Digital Logic Circuit is the Truth Table Table that describes the Output Values for all the combinations of the Input Values, called MINTERMS n input variables  2n minterms CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Combinational Circuits: Multiplexers CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Combinational Circuits: Encoder/ Decoder CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Latches: SR CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

D - Latches CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

D and JK Flip flops CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

T Flip flops CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Registers A register is a group of flip flops, each of which is capable of storing one bit of information. Clock inputs triggers all flip flops at the positive (rising) edge of each pulse. Clear input (low active) reset the all outputs to 0s. It must be 1 in normal operation. Four bits register CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Register with parallel load Transferring new information into the register is called loading the register. If all the bits of register are loaded simultaneously with a common clock pulse, the loading is called parallel load. To leave the content of the register unchanged, the input must held constant or the clock should be prohibited. The additional circuits play the role of MUX whose outputs drive data to the register either from the data bus or from the output of the register it self. CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Shift register A register that is capable of shifting the binary data from its current cell to a neighbor cell. The logical configuration is a chain of flip flops. The output of one flip flop is connected to the input of the next flip flop. All flip flops are connected to a common clock. CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Serial transfer CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Counters Counter is a register that goes through a prescribed sequence of states upon the application of input pulses. The input pulses may be a clock pulses, or they may originate from some external source. In general they either occur at fixed regular interval of time or at random. A counter that follows the binary number sequence is called a binary counter. An n-bit binary counter consists of n flip flops and can count in binary from 0 to 2n -1. CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Binary ripple Counters A binary ripple counter consists of a series of complementing flip-flops with output of each flip-flop connected to the C input of the next higher order flip-flop. The flip-flop holding the least significant bit receives the incoming count pulses. CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

BCD ripple counter CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

Synchronous counters CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018

The end of the Lecture Thanks for your time Questions are welcome CAO, by Dr. A.H. Abdul Hafez, CE Dept. HKU December 31, 2018