The memory of a computer is usually specified in GB (Giga Bytes) which is 1 billion bytes. A byte of memory consists of 8 bits of information. A bit is the smallest piece of information that can be stored in a computer. A bit has a value of either 0 or 1. In computer terms, it is a binary number which means it can have two possible values, 0 or 1. All information is stored in a binary format in the computer. For example, the number 2 is stored as 00000010 in a byte (8 bits) of information, and number 3 is stored as 00000011, etc.

 

Just as refresher to understand why memory is important, let revisit how a computer works.

 

The way the computer works is that when you start up the computer, the computer reads some critical information from the BIOS regarding the attached devices, boot sequence of devices such as CD ROM, Hard drive, etc. The CPU then reads information from your disk storage, specifically the operating system such as Windows 10 or MacOS, and loads it into memory. Therefore, it is important that the disk is fast to allow fast reading of this information and loading into the memory, more often called RAM (Random Access Memory). The RAM generally can be 100 times faster than the Hard Disk Drive (HDD), also known as hard disk or hard drive, so it is the hard drive that can slow this process. The reason the computer loads information into memory is that it can communicate 100s of times faster with memory as compared to hard disk. The more information stored in the memory, the better it is so that the CPU can get the information quickly from the memory and execute the instructions, i.e., the operating system instructions as well as applications. The memory is usually much smaller than the hard drive by 50 times or so, therefore the computer can only load a small portion of the hard drive contents into memory. Therefore, the size of the memory is very important. The larger the memory, the faster the CPU will be able to obtain the information and hence the computer will run faster. IN today’s world, 4 GB is minimum, but 8 GB or higher is recommended for a Windows 10 or MacOS machine.

 

In spite of the RAM being very fast, the CPU has its own little memory called the Cache which is even faster than RAM. As the cache is part of the CPU, it cannot be very large, but is critical. It stored the most frequently used items from the RAM in the cache so it can access the most frequently used data very quickly.

 

Commonly used RAM in today’s machines is DDR4 which is an abbreviation for Double Data Rate 4 RAM. This is faster than the previous generation DDR3 RAM. DDR3 RAM had clock cycles of 1066 MHz to 1866 MHz; the MHz represents the speed of the RAM. The higher the speed, that faster will be transfer of information between the CPU and the RAM. DDR4 RAM has clock cycles up to 3200 MHz and possibly higher. This implies that DDR4 RAM is much faster than the DDR3 RAM. However, the RAM to be used in a machine will depend on the motherboard design. Motherboard manufactures will provide information as to which memory type it supports, and which sizes of memory it supports.

 

It is important to note that when we refer to memory, specifically RAM, that is actually physical memory. On the other hand, there is something called virtual memory. Virtually memory actually is space allocated on a storage device such as HDD (hard disk drive) or SSD (Solid State Drive) to store information that the Operating System wanted to store in the RAM, but when the RAM is full, it stores some information in the virtual memory space allocated on the storage device. The more RAM a computer has, the less the need for virtual memory. Conversely, the less the RAM a computer has, the more the need to use virtual memory. As the virtual memory is on the storage device, it is not as fast as the RAM and hence the more the shortage of RAM, the more chances of virtual memory being used, the slower will be computer.

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