Chapter 1 Flashcards
What is computer architecture
This is the design and organization of computer systems, including hardware and how they interact with software.
What are the basic hardware units
They are
1. input units
2. output devices
3. CPU
4. Main Memory
5. ROM
6. Secondary storage
- Input units
This devices allows the useer to communicate with the computer.
for example: Pointing devices, scanner, digital camera, microphone, optical character recognition (OCR), optical mark reader (OMR), Barcode scanner.
- Output devices
Monitors and displays and printers.
- CPU
This is the brain of the computer, it interprets the instructions in the program and executes one by one. It is implement on a single silicon device known as the computer chip.
It performs the following:
- Transmission of data from input devices to memory.
- It process the data held in main memory
- Controls the transmission of information from main memory to output devices.
It contains the control unit and the arithmetic/ logical unit (ALU)
The control unit (CU)
it coordinates and controls all the operations carried by the computer.
it performs 3 operations repeadtedly
i. Fetch: fetches the next instruction from memory
ii. Decode: translate the program instructions into commands that the computer can understand.
iii. Execute: causes the instruction to be executed.
Arithmetic/logical units (ALU)
It performs two main operations
i. Arithmetic operations
ii. Logical operations (>,<,>=,<=,==).
- Main memory
The cycle (input-processing-output) would not be possible without a holding place for the instructions and data that the process can easily reach. this holding place is the main memory RAM and possibly ROM
What is RAM and their Types
- RAM:
. It holds instructions while the computer is in use
. It supports read/write operations
. Data in RAM can be accessed in any random format. that’s why the name random.
. Volatice memory
Type os RAM
i. Static RAM:
No refresh is needed, like the case of dynamic RAM. Expensive too. Dynamic RAM needs to be refreshed a thousands time every second. Both RAMS are volatile.
AS the speeds of computers increases, faster RAM chips are needed.
ii. SDRAM (Synchronous DRAM) Divides RAM into 2 separate memory banks. Increase speed too.
But SDRAM still have some limitations that the following computing technologies wants to resolve.
iii. RDRAM (Rmbus RAM)
Have a new memory design but expensive to implement.
iv. DDRSDRAM (Double Data Rate SDRAM). can transfer data twice as fast as SDRAM
ROM (Read Only Memory)
It is randomly access but read only
it is non volatile
Types of ROM
- ROM
It is read only and can only be produced by the mamnufacturer. - Programmable ROM (PROM)
Can be programmed using a PROM programmer. can be written to but only once. - Erasa le PROM (EPROM)
Can be erased and reprogrammed. - Electrically alterable ROM:
Can be modified a bit at a time. writing is slow. - EEPROM: most flexible, can be erased by a software. its used to hold BIOS programs.
Cache
It is a fast memory that is used to improve the speed of the computer some times doubling it.
it acts as an intermediate store between the CPU and the main memory.
it stores most frequently or recently accessed files.
[check fig 1.0]
Secondary Storage
These are devices used to store large amounts of data.
for example: Harddrive, Floppy disk, CD ROM, CD-R, CD-RW
Computer units interaction diagram [check fig 1.1]
