Page 57 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

A B C D a b c d e f g

0 0 0 0 1 1 1 1 1 1 0

0 0 0 1 0 1 1 0 0 0 0
0 0 1 0 1 1 0 1 1 0 1
0 0 1 1 1 1 1 1 0 0 1
0 1 0 0 0 1 1 0 0 1 1
0 1 0 1 1 0 1 1 0 1 1
0 1 1 0 1 0 1 1 1 1 1
0 1 1 1 1 1 1 0 0 0 0
1 0 0 1 1 1 1 1 0 1 1

Note
• For Common Anode type seven segment LED display, we only have to interchange all ‘0s’ and
‘1s’ in the output side i.e., (for a, b, c, d, e, f, and g replace all ‘1’ by ‘0’ and vice versa) and solve
using K-map.
• Output for first combination of inputs (A, B, C and D) in Truth Table corresponds to ‘0’ and last
combination corresponds to ‘9’. Similarly rest corresponds from 2 to 8 from top to bottom.

• BCD numbers only range from 0 to 9,thus rest inputs from 10-F are invalid inputs.

Registers
Flip flops can be used to store a single bit of binary data (1 or 0). However, in order to store multiple bits of data,
we need multiple flip-flops. N flip flops are to be connected in order to store n bits of data. A Register is a device
that is used to store such information. It is a group of flip-flops connected in series used to store multiple bits of
data. The information stored within these registers can be transferred with the help of shift registers.
Shift Register is a group of flip flops used to store multiple bits of data. The bits stored in such registers can be
made to move within the registers and in/out of the registers by applying clock pulses. An n-bit shift register can
be formed by connecting n flip-flops where each flip-flop stores a single bit of data. The registers which will shift
the bits to the left are called “Shift left registers”. The registers which will shift the bits to the right are called “Shift
right registers”. Shift registers are basically of following types.
Types of Shift Registers
• Serial In Serial Out shift register

• Serial In parallel Out shift register
• Parallel In Serial Out shift register
• Parallel In parallel Out shift register
• Shift Register Counter
Serial-In Serial-Out Shift Register (SISO)
The shift register, which allows serial input (one bit after the other through a single data line) and produces a se-
rial output is known as a Serial-In Serial-Out shift register. Since there is only one output, the data leaves the shift
register one bit at a time in a serial pattern, thus the name Serial-In Serial-Out Shift Register. The logic circuit
given below shows a serial-in serial-out shift register. The circuit consists of four D flip-flops which are connected
in a serial manner. All these flip-flops are synchronous with each other since the same clock signal is applied to
each flip-flop.
The above circuit is an example of a shift right register, taking the serial data input from the left side of the flip flop.
The main use of a SISO is to act as a delay element.
Serial-In Parallel-Out Shift Register (SIPO)

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CITS : E & H - Electronics Mechanic - Lesson 9 - 29