Moment 0 - Chapter 1 Flashcards
Computers process data under the control of sequences of instructions called?
computer programs.
Software programs guide the computer through ordered actions specified by people called?
computer programmers
A computer consists of various devices referred to as hardware, example?
the keyboard screen mouse hard disk memory DVD drives processing units
What is Moore’s Law?
Every year or two, the capacities of computers have approximately doubled inexpensively.
Moore’s Law and related observations apply especially to the amount of memory that computers have for programs, the amount of secondary storage (such as solid-state drive storage) they have to hold programs and data over longer periods of time, and their processor speeds—the speeds at which they execute their programs (i.e., do their work).
What are Input unit?
This “receiving” section obtains information (data and computer programs) from input devices and places it at the disposal of the other units for processing.
Most user input is entered into computers through keyboards, touch screens and mouse devices. Other forms of input include receiving voice commands, scanning images and bar codes.
What are Output unit?
This “shipping” section takes information the computer has processed and places it on various output devices to make it available for use outside the computer.
What are Memory unit?
This rapid-access, relatively low-capacity “warehouse” section retains information that has been entered through the input unit, making it immediately available for processing when needed. The memory unit also retains processed information until it can be placed on output devices by the output unit. Information in the memory unit is volatile—it’s typically lost when the computer’s power is turned off.
What are Arithmetic and logic unit (ALU)?
This “manufacturing” section performs calculations, such as addition, subtraction, multiplication and division. It also contains the decision mechanisms that allow the computer, for example, to compare two items from the memory unit to determine whether they’re equal. In today’s systems, the ALU is implemented as part of the next logical unit, the CPU.
What are Central processing unit (CPU)?
This “administrative” section coordinates and supervises the operation of the other sections. The CPU tells the input unit when information should be read into the memory unit, tells the ALU when information from the memory unit should be used in calculations and tells the output unit when to send information from the memory unit to certain output devices.
What are Secondary storage unit?
This is the long-term, high-capacity “warehousing” section. Programs or data not actively being used by the other units normally are placed on secondary storage devices (e.g., your hard drive) until they’re again needed, possibly hours, days, months or even years later. Information on secondary storage devices is persistent—it’s preserved even when the computer’s power is turned off.
Example of Secondary storage unit?
solid-state drives (SSDs)
hard drives
DVD drives
USB flash drives
What are Bits?
The smallest data item in a computer can assume the value 0 or the value 1.
What is Bits short for?
binary digit — a digit that can assume one of two values.
Digits, letters and special symbols are known as?
Characters
Computers process only 1s and 0s, so a computer’s character set represents every character as a pattern of 1s and 0s.
What dose ASCII stand for?
American Standard Code for Information Interchange
What is a Field?
A field is a group of characters or bytes that conveys meaning. For example, a field consisting of uppercase and lowercase letters can be used to represent a person’s name, and a field consisting of decimal digits could represent a person’s age.
Just as characters are composed of bits, fields are composed of?
characters or bytes
Several related fields can be used to compose a?
record (implemented as a class in Java).
Give an example of a record.
- Employee identification number (a whole number)
- Name (a string of characters)
- Address (a string of characters)
- Hourly pay rate (a number with a decimal point)
- Year-to-date earnings (a number with a decimal point)
- Amount of taxes withheld (a number with a decimal point)
Thus, a record is a group of related fields. In the preceding example, all the fields belong to the same employee.
A file is a group of?
related records
A database is a collection of?
Data organized for easy access and manipulation. The most popular model is the relational database, in which data is stored in simple tables. A table includes records and fields.
Big data applications deal with?
Massive amounts of data and this field is growing quickly, creating lots of opportunity for software developers. Millions of IT jobs globally already are supporting big data applications.
Programmers write instructions in various programming languages, some directly understandable by computers and others requiring intermediate translation steps. Hundreds of such languages are in use today. These may be divided into three general types:
- Machine languages
- Assembly languages
- High-level languages
What are Machine Languages?
Machine languages generally consist of strings of numbers (ultimately reduced to 1s and 0s) that instruct computers to perform their most elementary operations one at a time.
Any computer can directly understand only its own machine language, defined by its hardware design.
Machine languages are machine dependent (a particular machine language can be used on only one type of computer).
Translator programs called assemblers were developed to?
Convert early assembly-language programs to machine language at computer speeds.
What are Assembly Languages and Assemblers?
Instead of using the strings of numbers that computers could directly understand, programmers began using English-like abbreviations to represent elementary operations. These abbreviations formed the basis of assembly languages.
Why was high-level languages developed?
To speed the programming process, high-level languages were developed in which single statements could be written to accomplish substantial tasks. Translator programs called compilers convert high-level language programs into machine language.
High-level languages allow you to write instructions that look …
… almost like everyday English and contain commonly used mathematical notations.
What are Objects?
more precisely, the classes objects come from, are essentially reusable software components. There are date objects, time objects, audio objects, video objects, automobile objects, people objects, etc.
Performing a task in a program requires a?
Metod
The method houses the?
program statements that perform its tasks. The method hides these statements from its user; just as the accelerator pedal of a car hides from the driver the mechanisms of making the car go faster.
In Java, we create a program unit called a class to house the?
set of methods that perform the class’s tasks. For example, a bank-account class might contain one method to deposit money to an account, another to withdraw money from an account and a third to inquire what the account’s current balance is.
What is Instantiation?
Just as someone has to build a car from its engineering drawings before you can actually drive a car, you must build an object of a class before a program can perform the tasks that the class’s methods define.
The process of doing this is called instantiation.
An object is then referred to as an instance of its class.
Why reuse classes?
it saves time and effort. Reuse also helps you build more reliable and effective systems, because existing classes and components often have undergone extensive testing, debugging and performance tuning.
