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74181
The 74181 is a 4-bit slice arithmetic logic unit (ALU), implemented as a 7400 series TTL integrated circuit. The first complete ALU on a single chip, it was used as the arithmetic/logic core in the CPUs of many historically significant minicomputers and other devices. The 74181 represents an evolutionary step between the CPUs of the 1960s, which were constructed using discrete logic gates, and today's single-chip microprocessor CPUs. Although no longer used in commercial products, the 74181 is still referenced in computer organization textbooks and technical papers. It is also sometimes used in "hands-on" college courses to train future computer architects. Specifications The 74181 is a 7400 series medium-scale integration (MSI) TTL integrated circuit, containing the equivalent of 75 logic gates and most commonly packaged as a 24-pin DIP. The 4-bit wide ALU can perform all the traditional add / subtract / decrement operations with or without carry, as well as AND / NAND ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data General Nova
The Data General Nova is a series of 16-bit minicomputers released by the American company Data General. The Nova family was very popular in the 1970s and ultimately sold tens of thousands of units. The first model, known simply as "Nova", was released in 1969. The Nova was packaged into a single 3U rack-mount case and had enough computing power to handle most simple tasks. The Nova became popular in science laboratories around the world. It was followed the next year by the SuperNOVA, which ran roughly four times as fast. Introduced during a period of rapid progress in integrated circuit (or "microchip") design, the line went through several upgrades over the next five years, introducing the 800 and 1200, the Nova 2, Nova 3, and ultimately the Nova 4. A single-chip implementation was also introduced as the microNOVA in 1977, but did not see widespread use as the market moved to new microprocessor designs. Fairchild Semiconductor also introduced a microprocessor version of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arithmetic Logic Unit
In computing, an arithmetic logic unit (ALU) is a combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on floating point numbers. It is a fundamental building block of many types of computing circuits, including the central processing unit (CPU) of computers, FPUs, and graphics processing units (GPUs). The inputs to an ALU are the data to be operated on, called operands, and a code indicating the operation to be performed; the ALU's output is the result of the performed operation. In many designs, the ALU also has status inputs or outputs, or both, which convey information about a previous operation or the current operation, respectively, between the ALU and external status registers. Signals An ALU has a variety of input and output nets, which are the electrical conductors used to convey digital signals between the ALU and external circuitry. When an ALU i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
16-bit Computing
16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two most common representations, the range is 0 through 65,535 (216 − 1) for representation as an ( unsigned) binary number, and −32,768 (−1 × 215) through 32,767 (215 − 1) for representation as two's complement. Since 216 is 65,536, a processor with 16-bit memory addresses can directly access 64 KB (65,536 bytes) of byte-addressable memory. If a system uses segmentation with 16-bit segment offsets, more can be accessed. 16-bit architecture The MIT Whirlwind ( 1951) was quite possibly the first-ever 16-bit computer. It was an unusual word size for the era; most systems used six-bit character code and used a word length of some multiple of 6-bits. This changed with the effort to introduce ASCII, which used a 7-bit code and naturall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bit Slicing
Bit slicing is a technique for constructing a processor from modules of processors of smaller bit width, for the purpose of increasing the word length; in theory to make an arbitrary ''n''-bit central processing unit (CPU). Each of these component modules processes one bit field or "slice" of an operand. The grouped processing components would then have the capability to process the chosen full word-length of a given software design. Bit slicing more or less died out due to the advent of the microprocessor. Recently it has been used in arithmetic logic units (ALUs) for quantum computers and as a software technique, e.g. for cryptography in x86 CPUs. Operational details Bit-slice processors (BSPs) usually include 1-, 2-, 4-, 8- or 16-bit arithmetic logic unit (ALU) and control lines (including carry or overflow signals that are internal to the processor in non-bitsliced CPU designs). For example, two 4-bit ALU chips could be arranged side by side, with control lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
7400 Series
The 7400 series of integrated circuits (ICs) are a popular logic family of transistor–transistor logic (TTL) logic chips. In 1964, Texas Instruments introduced the SN5400 series of logic chips, in a ceramic semiconductor package. A low-cost plastic package SN7400 series was introduced in 1966 which quickly gained over 50% of the logic chip market, and eventually becoming ''de facto'' standardized electronic components. Over the decades, many generations of pin-compatible descendant families evolved to include support for low power CMOS technology, lower supply voltages, and surface mount packages. Overview The 7400 series contains hundreds of devices that provide everything from basic logic gates, flip-flops, and counters, to special purpose bus transceivers and arithmetic logic units (ALU). Specific functions are described in a list of 7400 series integrated circuits. Some TTL logic parts were made with an extended military-specification temperature range. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-bit Computing
In computer architecture, 4-bit integers, or other data units are those that are 4 bits wide. Also, 4-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, or data buses of that size. Memory addresses (and thus address buses) for 4-bit CPUs are generally much larger than 4-bit (since only 16 memory locations would be very restrictive), such as 12-bit or more, while they could in theory be 8-bit. A group of four bits is also called a nibble and has 24 = 16 possible values. Some of the first microprocessors had a 4-bit word length and were developed around 1970. Traditional (non-quantum) 4-bit computers are by now obsolete, while recent quantum computers are 4-bit, but also based on qubits, such as the IBM Q Experience. See also: Bit slicing#Bit-sliced quantum computers. The first commercial microprocessor was the binary-coded decimal (BCD-based) Intel 4004, developed for calculator applications in 1971; it had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carry-lookahead Adder
A carry-lookahead adder (CLA) or fast adder is a type of electronics adder used in digital logic. A carry-lookahead adder improves speed by reducing the amount of time required to determine carry bits. It can be contrasted with the simpler, but usually slower, ripple-carry adder (RCA), for which the carry bit is calculated alongside the sum bit, and each stage must wait until the previous carry bit has been calculated to begin calculating its own sum bit and carry bit. The carry-lookahead adder calculates one or more carry bits before the sum, which reduces the wait time to calculate the result of the larger-value bits of the adder. Already in the mid 1800s, Charles Babbage recognized the performance penalty imposed by the ripple-carry used in his Difference Engine, and subsequently designed mechanisms for ''anticipating carriage'' for his (never-built) Analytical Engine. Konrad Zuse is thought to have implemented the first carry-lookahead adder in his 1930s binary mechanical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
64-bit Computing
In computer architecture, 64-bit integers, memory addresses, or other data units are those that are 64 bits wide. Also, 64-bit CPUs and ALUs are those that are based on processor registers, address buses, or data buses of that size. A computer that uses such a processor is a 64-bit computer. From the software perspective, 64-bit computing means the use of machine code with 64-bit virtual memory addresses. However, not all 64-bit instruction sets support full 64-bit virtual memory addresses; x86-64 and ARMv8, for example, support only 48 bits of virtual address, with the remaining 16 bits of the virtual address required to be all 0's or all 1's, and several 64-bit instruction sets support fewer than 64 bits of physical memory address. The term ''64-bit'' also describes a generation of computers in which 64-bit processors are the norm. 64 bits is a word size that defines certain classes of computer architecture, buses, memory, and CPUs and, by extension, the software t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic Level
In digital circuits, a logic level is one of a finite number of states that a digital signal can inhabit. Logic levels are usually represented by the voltage difference between the signal and ground, although other standards exist. The range of voltage levels that represent each state depends on the logic family being used. A '' logic-level shifter'' can be used to allow compatibility between different circuits. 2-level logic In binary logic the two levels are logical high and logical low, which generally correspond to binary numbers 1 and 0 respectively. Signals with one of these two levels can be used in boolean algebra for digital circuit design or analysis. Active state The use of either the higher or the lower voltage level to represent either logic state is arbitrary. The two options are active high and active low. Active-high and active-low states can be mixed at will: for example, a read only memory integrated circuit may have a chip-select signal that is active-low ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Texas Instruments
Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog chips and embedded processors, which account for more than 80% of its revenue. TI also produces TI digital light processing technology and education technology products including calculators, microcontrollers, and multi-core processors. The company holds 45,000 patents worldwide as of 2016. Texas Instruments emerged in 1951 after a reorganization of Geophysical Service Incorporated, a company founded in 1930 that manufactured equipment for use in the seismic industry, as well as defense electronics. TI produced the world's first commercial silicon transistor in 1954, and the same year designed and manufac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
