About Cache memory

Cache memory is a temporary memory and usually has a small size than main memory ( RAM ) because it doesn't need to be with bigger capacity to perform well, cache memory is a fast memory that the processor uses for information it is likely to need again in the very near future. A computer processor is very fast and is constantly reading information from main memory, which means it often has to wait for information to arrive, because the main memory access times are slower than the CPU speed. Cache memory works on principles by copying frequently used data into the cache rather than requiring an access to the main memory to retrieve the data. 

Virtual memory

The purpose of virtual memory is to use the hard disk as an extension of RAM, thus increasing the available address space a process can use. Most personal computers have a relatively small amount ( typically less than 512 MB ) of main memory. This is usually not enough memory to hold multiple applications concurrently, such as word processing application, an e-mail program, and a graphics program, in addition to the operating system itself. Using virtual memory , your computer addresses more main memory on the hard driver.

Operating Systems, main task and types - Computer components

Operating system normally is common operating systems such as Windows, Linux and Mac OS, however. Operating system is a program that enables users to communicate with computers easily by providing interface and means of inputting data and present output on the other out put devices like screen. The interface of early operating system like DOS and CP/M were based on text and commands which needed to be typed in following precise rules, but today most operating systems provide graphical user interface ( GUI ).

Volatile and non-volatile - Types of memory to store data in computers

The computer has two types of memory of Storing files and data. You may have heard about RAM which means Random Access Memory or the main memory where the data and instructions are held to move from main memory to into registers , or to store programs instructions. RAM is considered as volatile because all data will be lost when is switched off. There is another type called non-volatile such as hard disk and ROM ( Read Only Memory ), hard disk also contains file storage memory which is used to store large amounts of data in the computer enable to keep data stored in. 

Types of magnetic and optical storage devices

 Compact Disk Read Only Memory ( CD-ROM ) which has two types of CDs that the computer uses, CD-R, ( Recordable ) and CD-RW, ( Rewritable ). This type uses a laser-based  optical form of storage. Data in CD-R disk cannot be changed afterwards, but in CD-RW users can rewrite or remove data. Also these types have a limit of storage size up to 800 MB or less, they are vary in their capacity. Digital Versatile Disk ( DVD ) it has the same way to read data, but DVDs have more than one layer of data because a signal data layer can have up to 4.2 GB at the highest quality for instance if data is audio or video. 

Express numbers in Scientific notation

Scientific notation is a kind of shorthand method to express numbers always used in computer science to represent large numbers. For example if we want to express any number in scientific notation we first divide the number by 10, then divide the result by 10 and so, until you get number less than 10. We want to represent 1673 in scientific notation, get the calculator and, 1673 / 10 = 167.3, 167.3 / 10 = 16.73, 16.73 / 10 = 1.673. Final result is 1.673 in scientific notation = 1673. This is quite simple as we see we divided it by 10 until it reduced to a number less than 10. 

How to convert binary to decimal and decimal to binary

This is the way to how to convert binary string to its decimal representation after we learned how to convert binary to hexadecimal and octal. We use the same way to do this and by all these steps from the previous post and this you will be able to convert binary number or string to all the other number representations. Assume we have this binary string 110010011101,  don't need to group them just add numbers as the rule of base 2 that after number 1 comes 2 and multiply by 2 to give us 4, then 4 multiply by 2 to give us 8 and so, put them on the top of binary string then add the values that have the truth value ( the truth value is 1 and false value is 0 ). 

How to convert binary to hexadecimal and octal in easy steps

In computer sciences during studying, programmers must know how to convert number for example from binary to decimal or hexadecimal and octal. It is in easy way we must know hexadecimal consists of 16 values, numbers and letters. Letters A, B, C , D, E, F , and 10 numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.You may want to know in hexadecimal we use 4 bits to represent one value, but in octal only 3 bits. Let's assume we have this binary string 110010011101, separate them as groups of bits as we said, 4 bits if we want hexadecimal and 3 if octal. 

Note: In hexadecimal A = 10, B = 11, C = 12, D = 13, E = 14, F = 15.

Signed integer representations, magnitude one's complement and two's complement

Using signed integer representations, signed magnitude, one's complement and two's complement. Signed magnitude its main purpose to use the remaining bits to clarify magnitude of numbers and always the positive numbers take the the same representation in one's or two's complement. In negative number the case is different and easy add or subtract two negative numbers and so. For example let's represent number 10 in binary. 10 in binary = 1010 we have four bits and you can imagine which limit you want like 8 bits that will contain the 10 representation, it will be 00001010 , all zeros on the left mean this number is a positive number.

What about -10 ?

In easy way, keep in mind negative number carries (1s) instead of zeros as the same with the above example for 00001010. which these zeros in the bit string 1111 you can call this high-order bit , the remained 1010 should be changed each bit to the negative. Watch this.

CPU Components , Control unit and Registers

Two parts of central processing unit ( CPU ) that make up all the CPU components. First part is the datapath or registers that thier tasks store data with the responsible for the basic arithmetic and logic unit ( ALU ). Second part is Control unit ( CU ) to control all instructions and make sure they will be delivered to the right place. Also control unit especially  is specialized as a responsible for fetching instructions from memory, decode them and transfer information or data to the arithmetic logic unit about type of information with the right register .

Logic Universal Gates - NAND gate

We discussed in previous post ( Digital computer circuits and Gates ) about that logical operators implemented by the gates like AND, OR and NOT. NAND gate is a universal gate because any function of electronic circuits can be done by using this gate, combination of AND, OR, NOT gates. NAND is easy to built because it is cheaper than the other gates in addition to that more complex integrated circuits can be built by using NAND gates instead of the other common gates.

Digital computer circuits and Gates - Basics of Boolean functions

Gates that can be found in digital computer circuits, actually they are numbers of transistors 1 to 6, but it is known as a one completed unit. The main task of gates is to implement Boolean functions such comparative between two things or more, this is also can be done with multiple input or output values. Gates for instance like ( And ) or ( OR ) and ( NOT ) which their values will be as the binary numbers 0s and 1s in machine language based on logically comparatives (true) and (false) that we have studied in mathematics class.This is example for the true table.

Introduction to Machine Language - definition - binary numbers and bits

Machine language is the only way that the processor's family understand which consists of binary numbers called bits or digits, only 1s and 0s , so each signal of instruction is a long stream these numbers or bits (1-0). Machine language is considered as a low level language even though these simple numbers 1s and 0s to write and also without interpreter or translator to translate the numbers to machine language, but it considered slower language to write a program and more difficult because to do simple instruction may transfer data or content of specific location in the main memory into the CPU, we have to provide many instructions to carry out simple task.