Computer Hard Drives

A hard drive is the hardware component that stores all of your digital content. Your documents, pictures, music, videos, programs, application preferences, and operating system represent digital content stored on a hard drive. Hard drives can be external or internal.

Everything stored on a hard drive is measured in terms of its file size. Documents (text) are generally very small whereas pictures are large, music is even larger, and videos are the largest. Digital files are measured in terms of megabytes (MB), gigabytes (GB), and terabytes (TB).

Do not confuse your Hard Drive with RAM (Ramdom Access Memory). RAM is Working Memory used by the Processor and is not used for storing files.

The Hard Disk is a small, sealed box that has been built into your computer and is not visible from the outside. There are three main features that distinguish the features of a Hard Disk: (1) Capacity, measured in Gigabytes and Terabytes. (2) The type of cable connecton: IDE or SATA (3) The newer Solid State Hard Drives.

IDE is a Parallel connection to the hard drive and SATA is a Serial connection. The main difference readily apparent is the cable that connects the drive to the mother board. One Important item to remember IDE and SATA Drives are NOT interchangeable, except by using a very special adaptor.

Hard Drive sata

Two IDE Drives on the Left and a Close up view of a SATA Drives Connectors on the Right

On the IDE hard drives, you will notice three sets of Pins on the rear of the Drive. The larger set on the left is the IDE connector. To the right of the IDE connector is the Jumper Setting pins then the four pin plug on the right is for the power supply cable.

The SATA Hard Drive on the Right has two sets of connectors, one for data and one for power, there are no jumper settings on a SATA Drive.


connector Sata

This is a picture of the IDE 80 Wire IDE Ribbon Cable on the Left. You will notice that there are three connectors. The Blue connector plugs into the motherboard and the other two are for Hard Drives.  Motherboards usually have two IDE connectors allowing for four devices.  The CD/DVD drive also connects to the motherboard with this cable. The hard drive will be Master and the DVD drive will be Slave and connect to the same cable.

On the Right is the SATA Drive with cables attached. Notice the data cable is much smaller than the IDE Ribbon cable.


IDE Jumper Settings

IDE Drives must be designated Master and Slave. Look at the Hard Drive for a table that shows the settings.



Remember: you can not have two masters or two slaves on the same cable.




SATA or Serial ATA drives are more straight forward that IDE drives, one drive per data cable. CD/DVD can also be SATA. Serial provides for a faster transfer of data then the parallel IDE cable. There are no jumper settings on a SATA hard drive


Sata Hard Drive close up of the connectors.



SATA Motherboard connectors.



SATA Data cable and the power supply cable connected to hard drive.


The other feature of a hard drive is the capacity,

Hard Drive capacity is measured in Bytes.

KB = Kilobyte = 1024 bytes

MB = Megabyte = 1,048,576 bytes

GB = Gigabyte = 1,073,741,824 bytes

Anything under 40GB is two small for the modern computer. IF you are purchasing a new PC, get the biggest one you can afford.  IF you have an older computer you will find in the instruction manual the maximum size hard drive the computer will support.

Older PC's have a hard drive barrier that they will not exceed.   512 MB, 2.1GB, 4.2GB, 8.4GB etc...

By today's standards 20-30 GB is considered small.  A drive of around 120GB will allow for plenty of capacity for everyday use.

IF you have a lot of pictures or other files you want to save, you can opt for an external hard drive.


These drives connect to the pc via the USB ports and you can have as many as you need. They can be plugged in and unplugged while the PC is turned on.

Solid State Hard Drives - SSD


This is a picture ↑of a Mechanical Drive (Left) and a Solid State Drive (Right). The Solid State Drive has no moving parts.


This is a picture ↑of a M2 type Solid State Hard Drive that connects directly to the Motherboard.


This is a picture ↑of a M2 type Solid State Hard Drive mounted on the Motherboard.

2.5 SSD

This is a picture ↑of a 2.5 inch laptop Solid State Hard Drive.

History SSD

Expected Life of an SSD. (Youtube Video)


HTML5 CSS - This page last updated on 27 Dec 2018.