1. READ-ONLY MEMORY (rom)
RANDOM ACCESS MEMORY (RAM)
and
READ-ONLY MEMORY (rom)

2. Definition of ram
 a computer memory on which data can be both read and written and on which the location of data does not affect the speed of its retrieval.
 RAM that acts as the main storage available to the user for programs and data

3. DYNAMIC RANDOM ACCESS MEMORY (dram) STATIC RANDOM ACCESS MEMORY (srAM)
To memory where any piece of data can be accessed almost instantly
Power supply must be constantly refreshed for it to work
Larger capacities because it is much more space- efficient and thus cheaper
MORE…..
Expensive
Faster
Power efficient
internal structure also makes it less dense
Types of ram

4. Has higher bandwidth, meaning greater speed
Synchronous dynamic random access memory (sdram)
Double data rate synchronous dynamic RAM (ddr sdram)
Most of the time the data needed by the CPU will be in sequence
Five percent faster than EDO RAM and is the most common form in desktops today
Maximum transfer rate to L2 cache is approximately 528 MBps
Just like SDRAM
Has higher bandwidth, meaning greater speed
Maximum transfer rate to L2 cache is approximately 1,064 MBps (for DDR SDRAM 133 MHZ)

5. How ram works?!
Similar to a microprocessor, a memory chip is an integrated circuit(IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data.

6. How much ram do you need?!
If you are running Windows XP, Microsoft recommends 128MB as the minimum RAM requirement.
For optimal performance with standard desktop applications, 256MB is recommended.
The amount of RAM listed for each system above is estimated for normal usage -- accessing the Internet, word processing, standard home/office applications and light entertainment.

7. How to manage virtual memory?!
Here below is a brief explanation of how to manage virtual memory .  The aim is simply increase the size of the paging file in order to have a larger sector of your hard disk acting like RAM on your PC. 

8. Steps Open your control panel and click on the System icon
Select the Advanced Tab 
Select the Performance Options Tab 

10. Select the Change Option found in the Virtual memory sub menu

11. Read-only memory (ROM)
Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. Because data stored in ROM cannot be modified (at least not very quickly or easily), it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to require frequent updates)

12. Different rom type memories
BIOS - is a programme for controlling the system's main input-output interfaces, hence the nameBIOS ROM which is sometimes given to the read-only memory chip of the mother board which hosts it.

13. bios

14. bootstrap loader
A programme for loading (random access) memory into the operating system and launching it.
This generally seeks the operating system on the floppy drive then on the hard disk, which allows the operating system to be launched from a system floppy disk in the event of malfunction of the system installed on the hard disk.

15. CMOS SETUP
Is the screen displayed when the computer starts up and which is used to amend the system parameters (often wrongly referred to as BIOS)

16. Power-On Self Test (POST)
Programme that runs automatically when the system is booted, thus allowing the system to be tested (this is why the system "counts" the RAM at start-up)

17. 1st STAGE of POST

18. 2nd stage of POST

19. Types of rom
PROM –(Programmable Read Only Memory) memories were developed at the end of the 70s by a company called Texas Instruments. These memories are chips comprising thousands of fuses (or diodes) that can be "burnt" using a device called a " ROM programmer", applying high voltage (12V) to the memory boxes to be marked. The fuses thus burnt correspond to 0 and the others to 1.

20. eprom
(Erasable Programmable Read Only Memory) memories are PROMs that can be deleted. These chips have a glass panel that lets ultra-violet rays through. When the chip is subjected to ultra-violet rays with a certain wavelength, the fuses are reconstituted, meaning that all the memory bits return to 1. This is why this type of PROM is called erasable.

21. EEPROM
(Electrically Erasable Read Only Memory memories are also erasable PROMs, but unlike EPROMs, they can be erased by a simple electric current, meaning that they can be erased even when they are in position in the computer.

22. Flash memory
Flash memory is denser, meaning that chips containing several hundred mega octets can be produced. EEPROMs are thus used preferably to memorize configuration data and the Flash memory is used for programmable code (IT programmers).

23. Examples of flash memory
Your computer's BIOS chip
Compact Flash (most often found in digital cameras)
Smart Media (most often found in digital cameras)
Memory Stick (most often found in digital cameras)
PCMCIA Type I and Type II memory cards (used as solid-state disks in laptops)
Memory cards for video game consoles

24. RAM vs. rom
RAM is Random Access Memory. It is a volatile type of memory that needs electricity to flow to retain information. It is the type of memory that computers use to process programs. ROM is Read Only Memory. Essentially it is a piece of permanently written information stored as memory. There are versions of this memory that can be rewritten but it is then called EPROM (Erasable Programmable Read Only Memory) and generally takes ultraviolet light to clear. The easiest way to understand the difference is to think of this as a blackboard. When memory is being used as RAM, it's a blackboard that is constantly being rewritten and then washed and rewritten, thousands of times per minute. If it was ROM, the writing would be in acrylic paint, that can't be removed. EPROM would be the same paint but it can be removed by very special and specific means.