- Arithmetic Logic Unit (ALU)
- Control Unit (CU)
- Memory Unit
1. Arithmetic Logic Unit (ALU):
Used to perform following operations.
- Arithmetic operation: +, -, *, %
- Logical operation: >, <, >=, <=, <>
2. Control Unit (CU):
- used to provide the necessary resources to complete the processing.
- also used to keep an accounting information about the available resources. Resources can be both hardware and software.
3. Memory Unit:
used to hold an instruction / information with security for the future puspose. On the basis of the working principle of memory devices, we can divide it into 2 different subunits. They are:
- Primary memory unit
- Secondary memory unit
Primary Memory Unit:
- used to hold the booting information
- booting makes a computer ready to do a work. During the booting, all the necessary system files are loaded into the memory. for eg. autoexec, exe, io.sys, config.sys etc.
- There are two differnet types of primary memory unit. They are ROM and RAM
ROM:
- Read only memory, also known as permanent memory.
- Naturally it is non-volatile.
- Manufacturer already provided an information to the ROM.
- 3 different subtypes: PROM, EPROM and EEPROM
PROM:
- Programmable read only memory.
- A software and hardware drive is used to add a content once. It is uneditable.
EPROM:
- Erasable PROM
- we can edit the content frequently but unable to overwrite.
EEPROM:
- Electronic EPROM
- easily add and remove the content according to our requirements.
RAM:
- Randam access memory.
- easily add and remove the content.
- naturally volatile, so we are unable to store our information for longer period of time.
- so it is also known as temporary memory.
- it is expensive.
- there are two types or RAM: SRAM and DRAM.
SRAM:
- Static Ram
- used to keep an information for the longest period of time. So it is fatser
DRAM:
- Dynamic Ram
- in a regular time frame it is used to flush the memory.
- so it is slower and cheaper than SRAM
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