# FLOW CONTROL

An overflow condition can be detected by observing the carry into the sign bit position and the carry out of the sign bit position. If these two carries are not equal, an overflow condition is produced. This is indicated in the examples where the two carries are explicitly shown. If the two carries are applied to an exclusive-OR gate, an overflow will be detected when the output of the gate is equal to 1.

**Frequently Asked Questions**

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Ans: When two numbers of n digits each are added and the sum occupies n + 1
digits, we say that an overflow occurred. When the addition is performed with
paper and pencil, an overflow is not a problem since there is no limit to the width of the page to write down the sum. view more..

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Ans: Subtraction of two signed binary numbers when negative numbers are in 2' s
complement form is very simple and can be stated as follows: Take the 2's
complement of the subtrahend (including the sign bit) and add it to the
minuend (including the sign bit). A carry out of the sign bit position is discarded. view more..

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Ans: The addition of two numbers in the signed-magnitude system follows the rules
of ordinary arithmetic. If the signs are the same, we add the two magnitudes
and give the sum the common sign. If the signs are different, we subtract the
smaller magnitude from the larger and give the result the sign of the larger magnitude. view more..

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Ans: An overflow condition can be detected by observing the carry into the
sign bit position and the carry out of the sign bit position. If these two carries are not equal, an overflow condition is produced. view more..

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Ans: The representation of decimal numbers in registers is a function of the binary
code used to represent a decimal digit. A 4-bit decimal code requires four flip-flops for each decimal digit. view more..

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Ans: The floating-point representation of a number has two parts. The first part represents a signed, fixed-point number called the mantissa. The second part designates the position of the decimal (or binary) point and is called the exponent. The fixed-point mantissa may be a fraction or an integer. For exam ple, the decimal number +6132.789 is represented in floating-point with a fraction and an exponent as follows: view more..

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Ans: A floating-point number is said to be normalized if the most significant
digit of the mantissa is nonzero. For example, the decimal number 350 is
normalized but 00035 is not. Regardless of where the position of the radix point
is assumed to be in the mantissa, the number is normalized only if its leftmost digit is nonzero. view more..

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Ans: In previous sections we introduced the most common types of binary-coded
data found in digital computers. Other binary codes for decimal numbers and
alphanumeric characters are sometimes used. Digital computers also employ
other binary codes for special applications. A few additional binary codes
encountered in digital computers are presented in this section. view more..

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Ans: Binary codes for decimal digits require a minimum of four bits. Numerous
different codes can be formulated by arranging four or more bits in 10 distinct
possible combinations. A few possibilities are shown in Table 3-6. view more..

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Ans: The ASCII code (Table 3-4) is the standard code commonly used for the
transmission of binary information. Each character is represented by a 7-bit
code and usually an eighth bit is inserted for parity (see Sec. 3-6). The code
consists of 128 characters. Ninety-five characters represent graphic symbols that
include upper- and lowercase letters, numerals zero to nine, punctuation marks, and special symbols view more..

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Ans: Binary information transmitted through some form of communication medium
is subject to external noise that could change bits from 1 to 0, and vice versa.
An error detection code is a binary code that detects digital errors during
transmission. The detected errors cannot be corrected but their presence is
indicated. The usual procedure is to observe the frequency of errors. If errors
occur infrequently at random, the particular erroneous information is transmitted
again. If the error occurs too often, the system is checked for malfunction view more..

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Ans: Parity generator and checker networl<s are logic circuits constructed with
exclusive-OR functions. This is because, as mentioned in Sec. 1·2, the exclusive-OR
function of three or more varia.bles is by definition an odd function.
An odd function is a logic function whose value is binary 1 if, and only if, an
odd
function
number of variables are equal to 1. According to this definition, the P( even)
is the exclusive-OR of x, y, and l because it is equal to 1 when either
one or all three of the variables are equal to I (Table 3-7). The P(odd) function is the complement of the P(even) function. view more..

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Ans: A digital system Is an interconnection of digital hardware module. that at'ClOinpl.lsh
a specific Wormation-proceaslna taslc. Digital systems vary in size and
complexi.ty
interacting digital
&om a few integrated circuits to a complex of interconnected and
computers. Digital system design invariably UBeS a modular
approach. The modules are constructed &om such digital components as
ules
registet&,
are in
decoders,
terconnected
arithmetic
with common elements
data and control paths
, and control logic. The
to fonn
various moda digital computer system. view more..

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Ans: The symbolic notation used to describe the microoperation transfers
among registers is called a register transfer language. The term "register
transfer" implies the availability of hardware logic circuits that can perform a
stated microoperation and transfer the result of the operation to the same or
another register. view more..

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Ans: Computer registers are designated by capital letters (sometimes followed by
numerals) to denote the function of the register. For example, the register that
holds an address for the memory unit is usually called a memory address
register and is designated by the name MAR. view more..

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Ans: where P is a control signal generated in the control section. It is sometimes
convenient to separate the control variables from the register transfer operation
by specifying a control function. view more..

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Ans: A typical digital computer has many registers, and paths must be provided to
transfer information from one register to another. The number of wires will be
excessive if separate lines are used between each register and all other registers
in the system. view more..

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Ans: The two selection lines S1 and S0 are connected to the selection inputs of
all four multiplexers. The selection lines choose the four bits of one register and
transfer them into the four-line common bus. When S1S0 = 00, the 0 data
inputs of all four multiplexers are selected and applied to the outputs that form
the bus view more..

## Recommended Posts:

- DATA TYPES
- NUMBER SYSTEM
- CONVERSION - INTRODUCTION
- OCTAL AND HEXADECIMAL NUMBER CONVERSION
- OCTAL AND HEXADECIMAL NUMBER CONVERSION -2
- Introduction to Decimal Representation
- ALPHANUMERIC REPRESENTATION
- Complements
- Complements -2
- Subtraction of Unsigned Numbers
- Subtraction of Unsigned Numbers-2
- Fixed-Point Representation
- Integer Representation
- Memory Transfer
- Binary Adder

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