What are the Different Types of Computer Memory

Are you up for looking different types of computer memory? You are on the right spot to know the answer of this question.

If you are wondering about the types of memory in a computer, the truth is that there are several. The memory hierarchy is not only made up of one type of memory.

Here you can learn what those types of memory are, their advantages and disadvantages, and the differences between all of them.

Different Types of Computer Memory

The types of memory in a computer are diverse, and have a well-defined hierarchy. That goes from the registers of the processors, to the secondary or massive storage media, through the cache memory, buffers, ROM memories, or the main memory or RAM. But what types are all of them?

See Also: What is the Main Memory of the Computer

Non-Volatile

Non-volatile memory is used to store microcode, BIOS firmware, and other code that should not be tampered with, software, user data, settings, etc.

However, the most modern computers have replaced these ROM memories with subtypes of it that allow them to be altered to support updates.

Here are some types of ROM memory and examples of use:

1. ROM (Read Only Memory)

This type of read-only memory can be implemented in various ways, such as integrated circuits, recording from the time of manufacture, as well as optical media such as a CD/DVD/BD.

Once recorded it is a non-volatile memory, so if it is disconnected from the power source it will remain intact, and cannot be erased in any way. That is why it is a good memory to store codes that have to remain unchanged.

2. PROM (Programmable ROM)

It is a ROM that can be programmed only once by a programmer. It uses a high voltage to destroy or create internal permanent links to record memory.

Like fuses that are blown or left intact to define the content. They can be used on some chips with microcode’s or routines that must remain intact.

3. EPROM (Erasable PROM)

Now goes one step further than the previous one, since it can be erased to be reprogrammed. It is performed using a UV light source that is generally exposed for 10 min or more.

These types of chips are easily recognizable, since they have a kind of window and are exposed to subject them to ultraviolet light.

See Also: What is STT RAM Memory and What is it for

These chips can be erased and reprogrammed for about 1000 cycles, and were used in old computers, now in disuse.

4. EEPROM (Electrically EPROM)

EEPROM is a type of EPROM memory that can be electrically erased and reprogrammed, without the need for UV exposure.

This type of memory has advanced over time, and is currently widely used in its flash version. It is used from buffers to SSDs, BIOS / UEFI with the ability to update, etc.

The great advantage of this is that by means of a superior current it can be erased and written hundreds and thousands of times.

On the other hand, there are also memories that can be considered programmable ROMs and are not based on semiconductor media like the previous ones:

5. Magnetic Memory

Like that of HDD hard drives, which is capable of storing binary data by magnetizing a platter or surface, depending on the N/S magnetic field used, zeros and ones can be represented.

They are not lost if power is stopped, they will remain and can be erased and recorded as many times as needed.

6. Optical Media

Such as CD/DVD/BD, which are polymer discs with reflective layers. A series of patterns (pits and lands) are recorded by laser or by molds to record information content permanently.

However, there are variations of these discs that are RW, that is, rewritable and rewritable and can be erased and rewritten up to 1000 times.

There is also another variant such as DVD-RAM that is similar to RW, but it is not necessary to erase the entire disc to be able to record other data.

Volatile or RAM

Volatile memory is a type of memory that will be erased when the power source stops supplying electricity.

All data inside will be lost. It is the memory type RAM (Random Access Memory). The random access memory is the main memory of the computer.

See Also: How to change RAM memory on PC

It is used to load data and instructions that make up the processes, so that the CPU can extract them from there for processing. Within this type of memory there are some subtypes.

1. DRAM (Dynamic RAM)

Dynamic RAM memory is a type of memory based on capacitors, which lose their charge progressively.

For this they need a dynamic refresh circuit that charge them while they are in use so as not to lose data.

• SDRAM (Aynchronous DRAM): It is a type of dynamic and synchronous memory that has generated a series of subtypes used mainly as main memory of the computer:

SDR SDRAM: Single Data Rate is a type of RAM memory with access times between 25 and 10ns and that has been used since the late 90s.

Rambus: It comes in RIMM modules and was used for Pentium 4s. The difference was that it was faster back then, but it was quite a bit more expensive. In addition, despite the slight advantage over the DDR, the latter ended up imposing itself.

Unlike SDRAM, its word size is smaller, only 16-bit compared to 64-bit SDRAM. But it works at a much higher speed, working with positive and negative edges, increasing bandwidth.

DDR SDRAM: Dual Data Rate is a synchronous, dynamic memory that is capable of sending data twice per clock cycle, compared to a single data in SDR.

In this way, it works at twice the speed of the system bus, increasing performance considerably without the need to increase the clock frequency.

See Also: In-Memory Vs Near Memory Computing

Currently, numerous improved versions of it have emerged, such as DDR2, DDR3, DDR4, and DDR5.

2. SRAM (Static RAM)

Unlike DRAM, this static memory is based on transistors instead of capacitors, and as long as it continues to be powered, it will keep the data, without the need for refreshing.

• NVRAM: is a type of non-volatile SRAM that preserves data even when power is interrupted. Generally, they can have a flash memory along with the RAM to store the data it contains and thus be able to retrieve it.
• Asynchronous SRAM: This type of memory does not usually have generous sizes due to its high cost, but it can range from a few Kb to tens of Mb. Its access time is very fast, and it can be used in many applications where speed is vital. They are used in some parts like switches, routers, etc.
• Synchronous SRAM: The difference with the previous ones is that they are not independent of the clock frequency, but are controlled by it. For example, they can be those of a processor’s cache, or the registers.

Now you know a little more about the types of memory in a computer, and you will understand a little better the hierarchy and the uses that are given to them. Don’t forget to comment!