CHAPTER 2 - COMPUTER ORGANIZATION Flashcards
Computer system
Hardware and software components that follow input, process, output, and storage model
CPU
Hardware component that performs basic arithmetic, logical and input/output operations in order to process data from input devices into useful information
4 components of CPU
CONTROL UNIT
ARITHMETIC LOGIC UNIT
MEMORY ADRESS REGISTER
MEMORY DATA REGISTER
CONTROL UNIT
Responsible for all operation in CPU; it controls retrieval of information from the primary memory and the sequence of their execution
MDR
It holds the data to be used by the ALU and saved to the RAM. To communicate with the primary memory, it is connected to the memory data bus.
Primary memory
the only memory directly accessible by the CPU. It may hold both data and instructions that are currently running on the computer system in binary machine code
ALU
Performs all the basic arithmetic, logical, input/output operations using instructions provided by the CU
MAR
It contains memory addresses of data to be used by ALU and processed data to be stored. To communicate with the RAM, it is connected to the memory address bus
Data bus
delivers data from the primary memory to the ALU and from ALU to the MDR and then to memory
RAM
A general purpose storage area meaning that data stored can be overwritten. This allows data ad instructions to be loaded for execution and used anytime necessary. However, it is volatile, meaning that if power is lost, the contents of the memory is lost as well. (E.g.: an open document with unsaved changes, when power is lost, all changes with be lost)
ROM
It is used to store data and instructions that cannot be overwritten. This means that data embedded in the ROM cannot be changed even when power is lost, therefore is non-volatile memory. It is also used to store data/instructions that does not need to be updated. (Ex: start up instructions of an OS)
Differences of RAM and ROM
- ROM cannot be written to, but RAM can written to
- ROM is non-volatile (permanent) while RAM is volatile
- ROM is much smaller than RAM
- ROM contains BIOS while RAM holds the programs running and data used
Cache memory
holds information from the RAM that is most actively used, and accessed frequently by the CPU; the computer system will run faster as the slower main memory will need to be accessed less frequently
How does cache memory work
When the processor needs to read from the main memory, it first checks if the copy of the data is available in the cache. If so, the processor would not have to access the slower main memory and reads from the cache, speeding up the process.
2 main types of RAM
- Dynamic RAM (DRAM)
- Static RAM (SRAM)
Differences between Cache memory and RAM
- Cache memory is near to CPU than RAM
- C.M more faster than RAM
- C.M more expensive than RAM
- C.M is separated in L1 and L2
Machine instruction cycle
It is a basic operation cycle of a computer, taking place in a definite time period, in which one instruction is fetched from the main memory and executed. It consists of 4 stages: fetch, decode, execute, and store.
Secondary memory
(auxiliary storage) is a relatively slow memory that may be written to like RAM but non-volatile like ROM; meaning contents are not lost if power is lost. Therefore, secondary memory is also called as persistent storage. It has a relatively high capacity to hold data compared to primary memory.
Types of secondary memory devices
- Flashdrives
- Hard disk drives
- Bluray disks
- CDS
- DVDS
- Magnetic tape
- Floppy disk
- Zip disk
Differences between primary and secondary memory
- P.M more expensive
- P.M faster than S.M
- P.M directly accessible by CPU
- S.M not directly accessible
- S.M non-volatile (retains data when power is lost)
- P.M volatile (doesn’t retain data when power is lost)
Operating System
It is a set of software that controls computer’s hardware resources and provide services for computer programs. It also acts as an intermediary between computer’s hardware and software applications.
Main services of OS
- Memory management
- Peripheral communication
- Resource monitoring and multitasking
- Networking
- Security
- Disk access and data management
Types of software application
- Word processors
- Spreadsheets
- Database management systems
- Web browsers
- Computer Aided Design (CAD)
- Graphic processing software
Difference between Spreadsheet software application and Database management System
- DTBM preserves data integrity easier
- SS can hold limited info
- SS can be used to produce charts/graphs using automated software tools
- DTBM used for various data associations that cannot be created with SS
Advantages and disadvantages of CLI and GUI
pros of CLI:
- easier to implement by a programmer
- requires less memory to run
cons of CLI:
- users need to remember specific commands = hard for new users to use
pros of GUI:
- users do not need to remember specific commands
- users use icons to remember commands; grouped in menus and toolbars
cons of GUI:
- requires more memory
- requires a graphical monitor and a pointing device