Last updated on August 10th, 2023 at 06:53 pm
Primary memory is also known as main memory or primary storage. Do not confuse this with secondary storage, where we talk about devices such as hard disk drives, CD-ROM drives, or flash drives.
What is primary memory exactly?
Main memory, primary memory, or primary storage is the memory that is accessed directly by the processor via a data bus. As a result, the processor is able to access information stored in primary memory much faster than that stored in secondary memory.
Keep reading to learn more about:
- The types of memory;
- The purpose of each type of memory;
- The types of RAM; and
- The types of ROM.
Types of primary memory
There are two main types of primary memory. These are:
- Random access memory (RAM); and
- Read-only memory (ROM).
What is random access memory?
Random access memory is that part of the computer where programs are stored when in use. Additionally, when information is being worked on, it is placed in primary memory or RAM. The processor accesses information directly from RAM. As a result, ram is the fastest, most expensive type of memory. Today it is not unusual to buy computers with 8 gigabytes of RAM. Undoubtedly this will continue to grow as technology evolves.
To explain this further, when a computer is turned on, the operating system software is loaded into RAM. When a user opens an application software, this is also loaded into the random access memory. Additionally, let’s suppose you have opened Microsoft Word to do some typing. The information that you are typing is stored in the random access memory throughout the period you are working on it. So if there is a blackout while you are preparing your document and you did not save it, when the computer is turned on again, you will find that the information is no longer there. So what is the cause of this?
When the computer is turned off, all the information stored in the random access memory is lost. This is because RAM is volatile – it only retains the information while the computer is turned on.
What is read-only memory? A definition of ROM
Read-only memory, as the name suggests, is a type of memory that cannot be changed. The processor is able to read the information stored on ROM, but it cannot be changed. No new information can be added to it.
Unlike RAM, ROM memory is non-volatile. As such, the data stored on it remains the same even when the computer is turned off.
You may be asking yourself, if ROM can only be read, how can it possibly have information stored on it? When ROM is created, data is also written to it. However, it cannot be changed or updated later. Some information stored on ROM includes booting code. This is information about how to start the computer when it is turned on.
So, what type of information is stored on RAM exactly? ROM contains information on how to complete different tasks. For instance, let’s say a user wishes to scan a document. The user indicates their desire to scan a document. The CPU checks RAM and finds the request to scan a document. The CPU then goes to ROM to retrieve the information on how to scan a document. The CPU then executes the task and returns the results. The user sends another request. The CPU then goes to RAM to grab the next task. Let’s say the user now wishes to print a document. The CPU will go to ROM to find out how to print. The CPU then prints the information. This process is constantly repeated throughout the period when the computer is in use. So the function of ROM is to store information about how to execute different tasks.
So what types of ROM are available today? There are three types of ROM available today. These are:
- Programmable read-only memory (PROM);
- Erasable and programmable read-only memory (EPROM); and
- Electrically erasable programmable read-only memory (EEPROM)