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New Technology and the Future
Published in Ervan Garrison, A History of Engineering and Technology Artful Methods, 2018
In this system a Binary digiT is a “bit.” Eight bits equal a byte (which corresponds to the number of data pins and lines of a data bus). One-half a byte is a nibble (“nybble”). Typically, one byte binary values are expressed in sets of nibbles like our number 141 is more correctly written 1000 1101.7 Inherent in the use of the binary system in computers is the obvious increase in steps necessary to represent number in binary form. For instance, to multiply two ten-decimal digits requires 1 — individual products plus additions. The same numbers require 32 binary digits to represent them and 1000 individual steps. In the economy of speed, the 10-fold increase in the number of computing steps is offset by the 1000-fold decrease in time necessary to accomplish them. Herein lay the triumph of the electronic digital computer. An interesting footnote to this discussion is the mode of operation for the computer. With the first machines like ENIAC, the computer operated in a serial mode as compared to parallel mode. In serial mode an operation like addition all corresponding pairs of digits are added serially in time. The difference lies with the parallel mode of operation adding corresponding pairs of digits simultaneously. Ultimately, the parallel mode of operation on binary numbers prevailed in modern computers. The serial mode has been maintained in the modern machines such as microcomputers in that one instruction at a time is inspected and executed by the device.
Number Systems, Operations, and Codes
Published in Syed R. Rizvi, Microcontroller Programming, 2016
Before we go further, it is important to define terms such as bit, nibble, byte, and octet. We will be using these terms frequently from now onward. A binary digit, abbreviated as bit, is the smallest unit of information in digital computing. In the binary world, a single bit can hold only one of two values: 0 or 1. More meaningful information is obtained by combining consecutive bits into larger units. For example, a nibble is composed of 4 consecutive bits. Since a nibble contains 4 bits, there are sixteen (24) possible values, so a nibble corresponds to a single hexadecimal digit. For example, F16 = 11112. A byte is also an ordered collection of bits. The size of a byte is typically hardware dependent, but the modern de facto standard is 8 bits, as this is a convenient power of 2. The term octet explicitly denotes a sequence of 8 bits because of the ambiguity associated with the term byte, and is widely used in digital computing. In short, a nibble is half a byte (octet). A byte (octet) is represented by two hexadecimal digits; therefore, it is common to display a byte of information as two nibbles. Thus, patterns like 3E and D2 are possible in a hexadecimal system, and a number like BF might not even look like a number at all. However, this system of writing binary numbers where every 8-bit byte becomes a two-digit hexadecimal (base 16) code only takes two print characters to write. This is a more compact way of writing the binary contents of a computer memory. In the hexadecimal system, 16 keys are needed for a keyboard, but the striking rate is only one-fourth of that required with a binary keyboard. Group Discussion: Why is the striking rate with hexadecimal keyboard only one-fourth of that required with a binary keyboard?
Performance Analysis of Multipliers Using Modified Gate Diffused Input Technology
Published in IETE Journal of Research, 2022
Y. G. Praveen Kumar, B. S. Kariyappa, S. M. Shashank, C. N. Bharath
Adder-2 is also a 8-bit adder, which adds the MSB nibble of first 4-bit multiplier’s output and sum output of Adder-1. This is realized using 3 FAs and 5 HAs rather than using 8 full adders for optimization. This adder would have required 80 transistors if implemented using 8 full adders in m-GDI but optimized adder-2 entails only 60 transistors. Schematic of Adder-2 is given in Figure 10. CMOS-based Adder-2 entails 184 transistors and this count has been reduced to 60 in the m-GDI technology. Higher nibble of Adder-2 output along with lower nibble of first 4-bit Vedic multiplier forms the lower byte of 16-bit final product.