Flip flop:
Flip flop is a one bit memory cell. It is used to strore either 0 or 1. To increase the storage capacity we need to use group of flip flops. It is also known to be latch.
Figure: RS Flip flop
History:
The first electronic flip flop was invented in 1918 by the british physicists William Eccles and F.W. Jordan. It was initially called the Eccies-Jordan trigger circuit and considered of two active elements. The design was used in the 1943 british colossus codebreaking computer. Though flip flops made from logic gates are common now.
Storing:
Figure: Group of flip flops to store 0s and 1s
Here, the clock will govern the flip flops to store the values in the each flip flop. And Synchronous means the clock and load will gradually increases, while asynchronous means only the load of the flip flop will increase.
Implementation:
Flip flops can be either asynchronous (simple) or synchronous (clocked). The asynchronous type can be described as latches, while the clocked ones are described as flip flops.
- Simple or asynchronous type flip flops can be built around a single pair of cross-coupled inverting elements like bipolar transistors, field effect transistors and inverters.
- Clocked or synchronous type flip flops are specially designed for ignoring their inputs except at the transition of a dedicated clock signal (known to be clocking or pulsing).
Register:
Using group of flip flops to store more data is known to be Register. Registers are locations where data or control information is temporarily stored.
Figure: Computer memory hierarchy
Figure: Registers in CPU
Program Counter:
A program counter is a register in a computer processor that contains the address of the instruction being executed at the current time. As each instruction gets fetched, the program counter increased its stored value by 1.
Figure: Program counter
Figure: Next instruction is stored in Program Counter
Shift Register:
Shift Registers are type of sequential logic circuits mainly for storage of digital data. The word shift means the device which shift the data from right or left i.e., calculator.
Figure: Shift Register
Figure: Different types of shift registers