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Numbering Systems and Coding Techniques
Published in David G. Johnson, Programmable Controllers for Factory Automation, 2020
ASCII is an acronym for the American Standard Code for Information Interchange and is pronounced “ask-ee.” This code is used for the communication for both letters and numbers, and is commonly found in use with a peripheral device like a CRT or printer. The ASCII code can be 6-, 7-, or 8-bits of length for each number, letter, or symbol. Even though it may appear that there are only 26 letters and the decimal numbers 0 through 9 to represent, there are actually many more. We must accommodate the upper and lower case of each letter, and also provide for the encoding of a number of control characters used in setting up communication with the external device. In spite of this newly expanded task, seven of the eight bits in each of our defined bytes are enough to delineate our code requirement. We can see this by recalling that 2 to the the 1th power equals 128. The eighth bit in the byte is sometimes used to define communication parity for error checking purposes. Note that two 8-bit byte encoded ASCII representations can be compacted in one 16-bit (two byte) word of the programmable controller memory. A partial ASCII table is shown in Table 3.4, a complete table is included as Appendix C.
Semiconductors and Digital Logic
Published in Syed R. Rizvi, Microcontroller Programming, 2016
The ASCII code for letter A is 100 0001. Since this word has two 1s, an even parity, the XOR gate will have an output of 0. Additionally, there is a NOT gate in addition to the ASCII code A at the output. Therefore, the overall output of the circuit is the 8-bit word 1100 0001. The point to note here is that this word has an odd parity. Now let us take the example of the letter C. The ASCII code for letter C is 100 0011. Since this word has three 1’s, an odd parity, the XOR gate will have an output of 1. Again, there is an inverter in addition to the ASCII code C at the output. Therefore, the overall output of the circuit is the 8-bit word 0100 0011. Again, the point to note here is that this word also has an odd parity. The circuit is called an odd-parity generator because it produces an 8-bit output word with odd parity. If the register word has even parity, 0 is the output of the XOR gate, and the odd-parity bit is 1. In the other case, when the register word has odd parity, the XOR gate has a 1 output, and the odd-parity bit is set to 0. Irrespective of the register contents, the odd-parity bit and the register bits form a new 8-bit word that will always have odd parity.
Data Types and Data Storage
Published in Julio Sanchez, Maria P. Canton, Microcontroller Programming, 2018
Julio Sanchez, Maria P. Canton
ASCII is a character encoding based on the English alphabet. ASCII was first published as a standard in 1967 and was last updated in 1986. The first 33 codes, referred to as non-printing codes, are mostly obsolete control characters. The remaining 95 printable characters (starting with the space character) include the common characters found in a standard keyboard, the decimal digits, and the upper- and lower-case characters of the English alphabet. Table 3.1 lists the ASCII characters in decimal, hexadecimal, and binary.
Adaptive synchronisation of memristor-based neural networks with leakage delays and applications in chaotic masking secure communication
Published in International Journal of Systems Science, 2018
ASCII (short for American Standard Code for Information Interchange) is a character encoding standard. ASCII codes represent text in telecommunication equipments, computers, execution routine and other devices. ASCII encodes 128 specified characters into 7-bit integers.