Flip-flops
Chapter4
Register
Registers,formed from a collection of
flip-flops,are used to store or manipulate
data or both.
Input and output function associated with
registers include
Parallel input / Parallel output
Serial input / Serial output
Parallel input / Serial output
Serial input / parallel output
Flip-flops have
two stable
state,can
store binary
code.
One flip-flop
can only store
one binary bit,D Q’
QC
Di
Qi Qi’
Store
Read
Clear
RD
Receive
Simple 1-bit register
Shift Register
Serial input / Serial output Shift register
Universal Shift Register
SN74LS194
Parallel input / parallel output
Four Parallel data inputs permit parallel loading
of external data.
Two serial input,one for left-shift,and the
other for right-shift,
Serial output data are taken from either
QA(LSB) or QD(MSB) depending on shift
direction.
Figure 5.104 (page 302)
Positive edge triggered
Two serial input,S0,S1
CLR can clear the data freely
Combined with clock pulse
S0S1=11,load the external data
S0S1=10,shift right,
(QAQBQCQD)n+1=(SRQAQBQC)n
S0S1=10,shift left,
(QAQBQCQD)n+1=(QBQCQDSL)n
S0S1=00,inhibit
SR A B C D SL
CLK
QA QB QC QD
CLR S0
S1
Homework
5,6
19
33,35,39