A) Read & translate the text.

The Arithmetic Logic Unit

(1) ALU (Arithmetic Logic Unit) is the high-speed CPU circuit that does calculating and comparing. Numbers are transferred from memory into the ALU for calculation, and the results are sent back into memory. Alphanumeric data is sent from memory into the ALU for comparing.

(2) The arithmetic logic unit is known to be the section of a computer where arithmetic or logical operations are performed on information. This unit often consists of three registers and associated control circuits. The first two registers receive the numbers to be operated upon and they are often called the A and В registers. The third register is often called the accumulator or the result register, and is the register where the results of arithmetic or logical operations are first produced. The results are tested by GOTOs; for example, IF ITEM A EQUALS ITEM B GOTO UPDATE ROUTINE.

(3) Arithmetic operations of a computer include addition, subtraction, multiplication and division, but also include shifting, complementing and fixed-point and floating-point operations. Shifting means multiplying or dividing a number by the power of the base of notation. For example, 1010 shifted two places to the left gives 101000. Shifting is regularly performed as a special rapid operation much faster than the usual multiplication or division. The complement of a number in decimal notation is the number obtained by replacing each decimal digit by nine minus that digit. For example, the complement of 734 is 265.

(4) Fixed-point operation in a computer is the operation assuming a fixed or constant location of the decimal point or the binary point, in each register of the machine, some computers operating in this way for reasons of simplicity of hardware. The dictionary Glossary defines the fixed point as a method for storing and calculating numbers in which the decimal point is always in the same location. It contrasts with floating point.

(5) Floating-point operation is the operation using a variable location of the decimal point or binary point. It consists of writing each number by specifying separately its coefficient, its exponent and its sign. For example, in floating-point operation, the number 6.04 x 10²³ might be written in a ten-place register as +6040000023 or +2360400000. In modern electronic computers, arithmetic operations are carried out at very high speeds. The dictionary Glossary defines the floating point as a method for storing and calculating numbers in which the decimal points do not line up as in fixed point numbers. The significant digits are stored as a unit called the mantissa, and the location of the radix point (decimal point in base 10) is stored in a separate unit called the exponent. Floating point methods are used for calculating a large range of numbers quickly.

Mantissa	Exponent	Value
6508	0	6508
6508	1	65080
6508	-1	650.8

(6) Floating point operations can be implemented in hardware (math coprocessor), or they can be done in software. In large systems, they can also be performed in a separate floating point processor that is connected to the main processor via a channel.

b) Complete the sentences according to the text.

1.thе arithmetic unit of a computer is the unit where… 2.The accumulator is... 3.Computers perform the following arithmetic operations… 4.A fixed-point operation in a computer is… 5.A floating-point operation is…

c) Give definitions to: an arithmetic unit /arithmetic operations /shifting /fixed-point operation /floating-point operation.

5.36 Give all possible derivatives to the verbs: to sum /to subtract /to multiply /to divide & translate them as in the given example.

E.g. Add складывать: addendum (pl. addenda) приложение, addition сложение, additional добавочный, additive добавка, added добавленный, additionally дополнительно.