Arithmetic and Logic Unit

Computer — A device capable of accepting information, applying prescribed processes to the information, and supplying the results of these processes. It usually consists of input and output devices, storage, arithmetic, and logical units, and a control unit. (Computer Dictionary, Sippl and Sippl)... 

A single processor system, depicted in Fig. 19.1 is usually composed of a controller, a data path, a memory, and an input/output unit. The functions of these units can be combined, and there are many names for each unit. The combined controller and data path are sometimes called the central processing unit (CPU). The data path is also called an arithmetic and logical unit (ALU). 

Arithmetic and logic unit (ALU) Primarily it performs the arithmetic and logical operations. It is tegulated by an instmction decoder. 

Datapath The components of the datapath may include registers, arithmetic and logic unit (ALU), shifter, bus. 

The computer s central processing unit (CPU) is the portion of a computer that retrieves and executes instructions. The CPU is essentially the brain of a CAD system. It consists of an arithmetic and logic unit (ALU), a control unit, and various registers. The CPU is often simply referred to as the processor. The ALU performs arithmetic operations, logic operations, and related operations, according to the program instructions. 

The CENTRAL PROCESSING UNIT (CPU) decodes and executes the instructions of a computer program. It has circuits that can perform arithmetic and logical operations, e.g., add two numbers or compare them for equality. 

On average, a typical computational process can keep four of the arithmetic functional units plus several memory and I/O units busy concurrently, allowing a single AFP to achieve an average computational rate of about 200 to 250 million 16-bit arithmetic and logical operations per second. 

The physical components of a computer form the hardware. Hardware includes the disk and hard drives, clocks, memory units, and registers for arithmetic and logical operations. Programs and instructions for the computer, including the tapes and disks for their storage, represent the software. 

ALU (arithmetic/logic unit) The part of the central processor of a computer in which simple arithmetic and logical operations are performed electronically. For example, the ALU can add, subtract, multiply, or compare two numbers, or negate a number. 

The arithmetic logic unit, or Al,l,i, of a CPU is made up of a series of registers, or accumulators, in which the intermediate results of binary arithmetic and logic operations are accumulated. The Intel Pentium 4 processor coniains nearly 50 million transistors and is capable of operating al clock speeds greater than 5.5 GHz. The Intel tianium processor contains 22 million transistors (the Itanium 2 processor has410 million transistors I. The fastest computers can execute nearly 1 billion instructions per second. 

Operation to functional unit binding All arithmetic and logic operations are bound to specific functional units using a functional partitioning method. 

Computer A functional unit that can perform substantial computations, including numerous arithmetic operations and logical operations without human intervention. 

Here is an example of a parameterized jV-bit arithmetic-logic-unit that performs an exclusive-or, less than, and an increment-by-1 operation. 

Here is a model of a different simple arithmetic-logic-unit. This logic unit performs four functions add, nand, greater-than and exclusive-or. A continuous assignment statement with a conditional expression is used to model the arithmetic-logic-unit. 

Chapter 3 describes how Verilog HDL constructs are collectively used to model hardware elements. While Chapter 2 describes the mapping of Verilog HDL to logic gates, this chapter describes the opposite scenario, which is, how to model a hardware element in Verilog HDL for synthesis. Elaborate examples are provided for many common hardware elements, such as multiplexers, counters, decoders and arithmetic-logic-units. 

Figure 1. Schematic diagram of the rocket-borne NfR spectrometer. Key A, amplifier S/H, sample and hold A/DC, analog-to-digital converter D/A, digital-to-analog converter and ALU, arithmetical logic unit. (Reproduced with permission from Ref. 3. Copyright 1981, American Institute of Physics.)...

The central processing unit (CPU) controls the overall operation of the computer. It is made up of electronic registers and logic circuits that execute the simple logical and arithmetic operations of which the computer is capable. When these operations are executed in appropriate sequences, the computer can accomplish complex mathematical or data-processing functions. Moreover, if one provides the appropriate electronic interface, these simple operations can be used to control experimental systems, acquire data, or print results on a teletype printer, line printer, oscilloscope, or other peripheral device. 

Design of a self-assembling, repairing and reconfiguring Arithmetic Logic Unit... 

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