dld lecture module 04 01
TRANSCRIPT
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Digital Logic & Design
Dr. Sajjad Ahmed Nadeem
Department of Computer Science & IT University of Azad Jammu & Kashmir
Muzaffarabad
Module-04 � Registers. � Register Transfer. � Binary Logic. � Gates.
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Register Transfer � The CU uses Registers to keep track of
various computer sequences. � Every input or output device must have at
least one register to store the information transferred to or from the device. � An inter-register transfer operation, a
basic operation in digital system, consists of a transfer of the information stored in one register to another.
Register Transfer
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Register Transfer � The input unit is assumed to have a
keyboard, a control unit, and an input register. � Each time a key is struck, the control
enters into the input register an equivalent 8 bit alphanumeric character code (assume code is ASCII). � The information from the input register is
transferred into the eight least significant cells of a processor register.
Register Transfer � After every transfer, the input register is cleared
to enable the control to insert a new 8 bit code when the keyboard is struck again. � Each 8 bit character transferred to the
processor register is preceded by a shift of the previous character to the next 8 cells on its left. � When the transfer of characters is completed,
the processor register is full, and its contents are transferred into a memory register.
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Register Transfer � To process discrete quantities of information in
binary form, a computer must be provided with, i. Devices that hold the data to be processed. ii. Circuit elements that manipulate individual bits of information. � The device most commonly used for holding
data is register. � Manipulation of binary variables is done by
means of digital logic circuits.
Register Transfer
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Register Transfer � Process of adding two 10 bit binary numbers. � Memory unit, which normally consists of
thousands of registers, is shown with only 3 of its registers. � Processor is shown with 3 registers, R1,R2,R3,
together with Digital Logic Circuit that manipulate the bits of R1 and R2 and transfer into R3, their sum.
Register Transfer � Information stored in memory can be
transferred to processor registers, and Results obtained in processor registers can be transferred back into a memory register for storage. � The registers of a system are the basic elements
for storing and holding the binary information. � The Digital Logic Circuits process the
information.
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Binary Logic
� Binary Logic deals with variable that take on two discrete values and with operations that assume logical meaning. � Binary logic is used to describe in a
mathematical way, the manipulation and processing of binary information. � It is particularly suited for the analysis and
design of digital systems. � It is also termed as Boolean Algebra.
Boolean Algebra
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Operator Precedence
Binary logic � Binary logic deals with variables that take on two
discrete values and operations that assume logical meaning.
� Logic gates: electronic circuits that operate on one or more input signals to produce an output signal.
� Example x y x AND y 0 0 0 0 1 0 1 0 0 1 1 1
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