Building a parity block with a parity byte

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. When building a parity block, what is added to each data byte first?

A A row parity bit on the end of each byte

B One parity bit for the whole block

2. How is each bit of the parity byte worked out?

A From the bits in one row, going across a single byte

B From the bits in one column, going down all the bytes

3. Even parity: a column holds 1, 0, 1, 1. What is that column's parity bit?

A 1

B 0

4. Odd parity: a column holds 1, 1, 0, 0. What is that column's parity bit?

A 0

B 1

5. Even parity: what row parity bit goes on the end of the byte 01101011?

A 1

B 0

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
11010001 -> 10100011		A0110000 -> 01100000
2Column 3: 1, 1, 1 -> 1		BRow parity bits 1, 0, 0 -> corner bit 1
3Row parity bits are added first, one at the end of each byte (even parity)		CThis column has three 1s, so the parity byte holds a 1 for this column to make the count even.
4The corner bit is the parity bit of the row parity bits, so it checks in both directions		DA row parity bit is added to the byte. There are three 1s, so the even parity bit is 1.
51111000 -> 11110001		EThe column has one 1, which is odd, so the even parity bit should be 1, not 0.
6Column 4: 0, 0, 1 -> parity bit 0		FThe byte already has four 1s, which is even, so the even parity bit should be 0, not 1.

Definitions

parity block

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Row 1: 1011001 + parity bit _ = 10110010

Row 2: 0110100 + parity bit _ = 01101001

Column 4 holds 1, 0, 0 so its bit is _

Row parity bits are added first. Column parity bits make the parity ____.

Parity bits down the last column: 0, 1, 0 Corner bit (even parity) = _

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A even parity block

B 1011001 0

C 0110100 0

D 1100110 0

E 0001011 1

Question 2

A 1 Make the parity byte first

B 2 Column parities form a byte

C 3 Corner bit checks both ways

Question 3

A Even parity, 3 rows

B Column 4 bits: 1 1 0

C Count of 1s: one

D Parity byte bit 4 is 1

Question 4

A even parity block

B 1010111 1

C 0111010 0

D 1101101 0

Question 5

A odd parity block

B 0110101 1

C 1000001 0

D 1110000 0

E 1111011 1

Answer Key

Building a parity block with a parity byte

Section A: Quick Questions

A — A row parity bit on the end of each byte

B — From the bits in one column, going down all the bytes

A — 1

B — 1

A — 1

Section B: Match the Pairs

1010001 -> 10100011 → A row parity bit is added to the byte. There are three 1s, so the even parity bit is 1.

Column 3: 1, 1, 1 -> 1 → This column has three 1s, so the parity byte holds a 1 for this column to make the count even.

Row parity bits are added first, one at the end of each byte (even parity) → 0110000 -> 01100000

The corner bit is the parity bit of the row parity bits, so it checks in both directions → Row parity bits 1, 0, 0 -> corner bit 1

1111000 -> 11110001 → The byte already has four 1s, which is even, so the even parity bit should be 0, not 1.

Column 4: 0, 0, 1 -> parity bit 0 → The column has one 1, which is odd, so the even parity bit should be 1, not 0.

Section C: Definitions

parity block — Each byte gets a row parity bit, then a final parity byte holds the parity bit for each column. The corner bit is the parity bit of the parity bits, so it checks in both directions.

Section D: Fill in the Blanks

Row 1: 1011001 + parity bit 0 = 10110010

Row 2: 0110100 + parity bit 1 = 01101001

Column 4 holds 1, 0, 0 so its bit is 1

Row parity bits are added first.
Column parity bits make the parity byte.

Parity bits down the last column: 0, 1, 0
Corner bit (even parity) = 1

Section E: Spot the Error

C — 0110100 has three 1s. With even parity the row parity bit must make the total even, so it should be 1, not 0. The row should read 0110100 1.

A — The row parity bits come first. Each byte gets its own parity bit, and only then are the column parity bits worked out to make the parity byte. Step 1 should be: Give each byte a parity bit.

B — The column bits are 1 0 0, which contain one 1. That is why the next line says one, and the parity byte bit 4 must be 1 to make the total even. The broken line shows two 1s.

D — The corner bit is the parity bit of the parity byte's other bits. 1101101 has five 1s, so with even parity the corner bit must be 1, not 0. The last line should be 1101101 1.

C — 1000001 has two 1s. With odd parity the whole byte must have an odd number of 1s, so the parity bit must be 1, not 0. The row should be 1000001 1.