### Computing & Informatics - short answer type questions from AMIE exams

What is the purpose of the exit () command?
To quit a program

What is a global variable? How long does a global variable remain alive?
Global variables are those variables that are visible to all functions. Any function can read/modify them. Global variables remain till the program terminates.

What do you mean by a pointer variable in C programming? Give an example.
A pointer is a variable that stores the address of another variable. Unlike other variables that hold values of a certain type, a pointer holds the address of a variable. For example, an integer variable holds (or you can say stores) an integer value, however, an integer pointer holds the address of an integer variable.
Syntax:
datatype *var_name;
int *ptr;   //ptr can point to an address which holds int data

Explain how one can recall a previously used DOS command by pressing some key.
Using F9 key

What happens when the following command is used?
chmod u = rwx,go=r-x foo
The access mode of the file is changed, the user is given read, write and execute permission. group members and others are given only read and execute (r & x) permission.

Transform (37.24)₈ into its equivalent binary form.
The output will be 11111.0101
Steps:
You enter the number: 37.248 in the Octal number system and want to translate it into Binary.
To do this, at first translate it to decimal here so :

37.248 = 3∙81+ 7∙80+ 2∙8-1+ 4∙8-2 = 24 + 7 + 0.25 + 0.0625 = 31.312510

Converting 31.312510 in Binary system here so:

The whole part of a number is obtained by dividing on the basis of new

Hence 0.312510 = 0.01012

Add up together whole and fractional part here so:

111112 + 0.01012 = 11111.01012

Result of converting:
37.248 = 11111.01012

What do you mean by secondary memory? Give an example.
Secondary memory is where programs and data are kept on a long-term basis. Common secondary storage devices are hard disk and optical disks. The hard disk has enormous storage capacity compared to the main memory.

What is an electronic data interchange? Give one of its applications.
Electronic Data Interchange (EDI) is the electronic interchange of business information using a standardized format; a process that allows one company to send information to another company electronically rather than with paper. Business entities conducting business electronically are called trading partners.

List different types of computer networks.
LAN (Local Area Network), WAN (Wide Area Network), MAN (Metropolitan  Area Networks)

What is sequential logic? Give an example.
In digital circuit theory, sequential logic is a type of logic circuit whose output depends not only on the present value of its input signals but on the sequence of past inputs, the input history. This is in contrast to combinational logic, whose output is a function of only the present input.