IS 310 Chapter 5

What is an unsigned integer?

A positive whole number represented without a sign.

What is BCD?

Binary-Coded Decimal, where each decimal digit is represented separately in binary.

How many bits does BCD use for each decimal digit?

4 bits.

How does BCD differ from conventional binary?

BCD represents each decimal digit separately, while binary represents the entire number in binary.

Which has a greater range for the same number of bits: BCD or binary?

Conventional binary.

Why is conventional binary generally preferred?

It provides a greater range of values and makes calculations easier.

Why can BCD be useful for business applications?

It maintains decimal rounding and decimal precision.

What are the three signed-integer representations in the slides?

Sign-and-magnitude, 1's complement, and 2's complement.

Which signed-integer representation is the most common?

2's complement.

How does sign-and-magnitude represent the sign?

The left-most bit represents the sign: 0 is positive and 1 is negative.

What is the range of an 8-bit sign-and-magnitude number?

-127 to +127.

How many representations of zero does sign-and-magnitude have?

Two: +0 and -0.

What is 1's complement?

A signed-number representation that uses inversion to represent negative numbers.

How do you find the 1's complement of a binary number?

Change every 1 to 0 and every 0 to 1.

In 1's complement, what does a number beginning with 0 mean?

The number is positive.

In 1's complement, what does a number beginning with 1 mean?

The number is negative.

What is the range of an 8-bit 1's complement number?

-127 to +127.

How many representations of zero exist in 1's complement?

Two.

What is 2's complement used for?

Representing signed positive and negative binary numbers.

What is the range of an 8-bit 2's complement number?

-128 to +127.

How many representations of zero exist in 2's complement?

One.

What is overflow?

A result that is outside the range that can be represented by the fixed number of bits.

How can overflow be detected when adding signed numbers?

If both inputs have the same sign but the result has a different sign.

What is a carry flag?

It is set when an addition or subtraction result exceeds the fixed number of allocated bits.

What is end-around carry in 1's complement?

A carry beyond the fixed word size is added back into the result.

How is subtraction performed using 1's complement?

Subtraction is treated as adding a negative number.

What is a modulus in the 2's complement slide?

A base-2 1 followed by the specified number of 0s

What modulus is shown for 8 bits?

1000 0000.

What two methods does the slide give for finding the 2's complement

Subtract the value from the modulus or invert.