Write out the vertical horizontal parity code that transmits word , where the even check is used!

Parity is a very simple and widely used check method.

This method adds a parity bit to each byte and transmits it, i.e. nine bits of data are sent per byte.

Before data transmission, it is common to determine whether it is an odd or even check to ensure that the sender and receiver use the same check method for data validation.

If the check digits do not match, the transmission is considered to be wrong.

The odd check is to add an additional bit after each byte so that the total number of "1s" is an odd number.

When the odd check is done, the check digit is set according to the following rules: if the number of "1" in the data bits per byte is an odd number, the check bit is "0"; If it is an even number, the check digit is "1".

Odd checksums are often used for synchronous transmissions.

The evenness check adds an additional bit after each byte so that the total number of "1s" is even.

In the case of even check, the check digit is set according to the following rules: if the number of "1" in each byte of data bits is an odd number, the check bit is "1"; If it is an even number, the check digit is "0".

Even checks are often used for asynchronous or low-speed transfers.

The principle of verification is: if the odd check is used, the number of "1" must be odd in a character encoding (including check digit) sent by the sender, and the number of "1" in the binary bits of the receiving character is counted at the receiving end, if the number of "1" is counted as an even number, it means that there is an error of 1 bit (or odd bit) in the transmission process.

In fact, there is the most chance of occasional bit errors in transmission, so parity is often used.

However, parity is not a safe method of error detection and has a low ability to identify errors.

If the number of digits in which the error occurred is an odd number, then the error can be identified, but when the number of digits in which the error occurred is an even number, the error cannot be identified because the errors cancel each other out.

Digit-bit errors, and most errors involving an even number of bits, can go undetected.

The disadvantage is that when one or more digits in a data segment are corrupted, and the corresponding bits with opposite values in the next data segment are also corrupted, the sum of these columns will not change, so it is impossible for the receiver to detect the error.

Commonly used parity methods are vertical parity, horizontal parity, and horizontal vertical parity.

Horizontal parity is the addition of a check bit in the form of a row in the horizontal direction.

Figure 3 Data format and sending order during horizontal parity.

Figure 4 An example of a horizontal parity method.

where m is the number of digits of the codeword, and n is the number of codewords.

Let the encoding efficiency of horizontal parity be r, then:

Horizontal parity, also known as horizontal parity, can not only detect the odd number of errors that occur on the same bit in each segment, but also detect all burst errors of burst length m, and its missed detection rate is lower than that of the vertical parity method, but when implementing horizontal parity, data buffers must be used.

Parity check code belongs to error detection coding, which can only detect errors and cannot correct them, nor can they detect double-digit errors, and CRC is also yes, and it does not have error correction function, but Hemming code has error correction function. Parity is a general term for odd check code and even check code, and the odd check code (or even check code) with code length n consists of (n) 1 bit of information and a check element. In practical applications, it is divided into vertical parity code, horizontal parity code and horizontal and vertical check code.

Parity: It is an encoding method that increases redundant bits to make the number of "1" in a character always odd or even.

For example: odd check: In all transmitted digits (including each digit of characters and check digits), the number of "1" is always an odd number, such as:

Even check: The number of "1" is always an even number in all transmitted digits (including each digit of characters and check digits), for example:

In addition, the parity encoding method can only detect part of the error in the process of information transmission (1-bit error can be detected, 2-bit or more error cannot be detected), and after the error is found, it can only be required to be retransmitted, but the error cannot be corrected.

Parity is a way to make a codeword by adding redundant bits"1"The number of numbers is always odd or even, and it is an error detection code. In actual use, it can be divided into vertical parity, horizontal parity and horizontal vertical parity.

Parity is the verification of the correctness of the data, there are 8 bits in each byte in memory, and the parity code is the check that the 1 in each byte is odd or even.

Due to interference, it is possible to change the bit to 1, which is called a "bit error". We call how to find errors in transmission "error detection". After discovering an error, how to eliminate the error is called "error correction".

The simplest method of error detection is "parity", which means that one additional bit of parity is passed in addition to the characters being transmitted. Odd or even checks can be used.

Parity can detect some bit errors in the process of information transmission (1-bit bit error can be detected, 2-bit or more bit error can not be detected), and at the same time, it cannot correct errors. After discovering an error, you can only ask for a retransmission. However, due to its simple implementation, it is still widely used.

There are some error detection methods that have the ability to automatically correct errors. Such as cyclic redundancy code (CRC) error detection.

This question chooses d, because the first place of the character code is the check digit, because the true value of d has three 1s, so the check digit is written as 1 to make up an even number, which is also called even check. Although the question does not specify whether it is an odd check or an even check, because it is a multiple-choice question, it can be deduced that only the even check will have the only correct one.

Parity check is a method of verifying the correctness of a transmission. According to the set of binary ** digits that are transmitted"1"The number of is odd or even. The odd number is called the odd check, and the opposite is called the even check.

Odd parity: The number of 1s in the transmitted data (including the check digits) is an odd number. That is, if the number of 1s in the transmitted byte is an even number, the check digit is "1" and the odd number is reversed.

Even parity: The number of 1s in the transmitted data (including check digits) is even. That is, if the number of 1s in the transmitted byte is an even number, the check digit is "0", and the odd number is reversed.

Parity codes are divided into odd check digits and even check digits.

You can't see it if you look at it like this, you have to agree in advance whether it is an odd check or an even check, and the odd check is as the name suggests, that is, when the binary data has an odd number of 1s, the odd check code is 1, otherwise, when the odd check code is 0 when there are even 1s

The reverse is true for even checksums, which means that when the binary data has an even number of 1s, the even check digit is 1, otherwise the odd check digit is 0 when there is an odd number of 1s

This should be a binary ASCII code, binary ASCII code only the first seven bits are valid bits, the highest bit is 0, so the highest bit is usually used for parity.

In the case of the couple check, the number of all bits of 1 is even.

Then the check encoding of the data you said should be 10100101, that is, write 1 as the even check digit in the highest bit, so that when the data is transmitted, the total number of 1 is an even number to achieve the purpose of check.

If the number of the first seven digits of your data is an even number, you should write 0 in the highest digit for even verification, that is, you can achieve the purpose of verification without changing the highest digit, because the highest digit of the ASCII code is originally 0.

If you are originally passing a 7-bit data, you can also understand it in this way, I hope you can understand it when I say this, I hope it will help you.

1000110 (0) must be added 0, so that there are 3 1s that are already odd numbers, so after adding 0, the number of 1s is still an odd number.

Odd and even check (ECC) is a way to correct data errors when data is transmitted, which is divided into two types: odd check and even check.

If odd check is employed, an extra bit is added as the check bit for each byte transmitted. When the number of "1" in the actual data is even, the check digit is "1"; Otherwise, the check digit is "0" to ensure that the transmitted data meets the odd check requirements.

After receiving the data, the receiver checks the number of "1s" in the data according to the requirements of odd number verification. If it is an odd number, the transmission is correct; Otherwise, it means a transmission error.

The so-called parity is to implement the set rules, and after the set, there is only one way to check, so your problem is actually two problems.

If it is set beforehandOdd check(The.)Validation principlesYes: Checks whether the number of 1 in the received data is 1Odd numberIf it is, it is correct, and if it is not, the CPU is judged to be a bit error).0 plus odd check digit is0--- say a word more to aid in understanding that under this condition if your data is0, then adding the odd check digit is 0

The same goes for the same thing, if it is set in advancePuppet checks(The.)Validation principlesYes: Checks whether the number of 1 in the received data is 1Even numberedIf it is, it is correct, and if it is not, the CPU is judged to be a bit error).0 plusEven check digitsIt's 0

So with parity, what kind of data is received by the data receiver (assuming there are no bit errors) is thisThe two points are jointly decided：1.Verification method; 2.The number of 1 pieces of data to be transferred.

The first question should be about the setting of the parity bit during the sending process, right?

In the MCS51 MCU seriesFor odd checks, if the data to be sent in a(acc) is to be sent before sending, this is the case.

11010010, we just need to negate the binary value in p() and put it into tb8 (i.e., the parity bit here).

For this question, the number of "1s" in the data to be sent is an even number of 4, so p is 0,So the value in the parity bit should be set to 1

In addition, for odd checks, when we receive them, we should do the "1" of the data bit and the parity bitThe sum of the numbersIf it is an odd number of "1s", it means that the data transmission is correct.

Parity is a method of verifying the correctness of a transmission. The verification is performed based on whether the number of "1s" in the number of digits in the transmitted binary ** is odd or even. The odd number is called the odd check, and the opposite is called the even check.

The type of calibration to be used is predetermined. Usually a parity bit is set up specifically to make the number of "1s" in this group of ** odd or even. If the odd check is used, when the receiver receives this group of **, check whether the number of "1" is an odd number, so as to determine the correctness of the transmission **.

Generally, the check position is placed at the front, and the odd check is 111010010

0, the total number of check digits for odd checks should be odd.

0。Because there are already odd numbers of 1s.