RAM explained in byte-sized chunks

JPCT 150713 Alan Stainer. Photo by Derek Martin
JPCT 150713 Alan Stainer. Photo by Derek Martin

Alan Stainer runs an IT company specialising in technical advice and support and website design, based in the Horsham District. In each column he’ll look at issues affecting computer use.

Have you ever wondered what a mega whatsit is, or a tera thingamy?

It is something that us computer experts talk about all the time. In fact, we happily throw around jargon like there is no tomorrow. It could be a completely different language to the untrained ear.

Time to dispel some of the mystery then.

Let’s start with RAM (Random Access Memory). It is the part of the computer (or smartphone/tablet) that holds information ready to be processed by the CPU (Central Processing Unit). We measure RAM in bytes, but the smallest measurement is actually a bit. Computers are binary devices and a bit represents either on or off (1 or 0 in binary). A byte is equivalent to 8 bits. We measure hard disk capacity in the same way.

What about mega doodad whatsits? I am getting to that. Bytes scale up very fast, so we abbreviate things. Kilo in this case is not 1000 as it is using the decimal system, but 1024. Here is a quick summary.

l 8 bits = 1 byte

l 1024 bytes = 1 kilobyte (KB)

l 1024 kilobytes = 1 megabyte (MB)

l 1024 megabytes = 1 gigabyte (GB)

l 1024 gigabytes = 1 terabyte (TB)

l 1024 terabytes = 1 petabyte (PB)

What does it actually mean?

This column is around 20 Kbs in size, while a reasonable definition photo can be 4 or 5 MBs. A DVD can usually store a maximum of 4.7 GBs, while a music CD can only store 700 MBs.

Now, I want to RAM this home as it does get confusing. RAM is not the same as hard disk space. RAM does not store anything while the computer is switched off, a hard disk does. RAM is used for processing data, a hard disk stores data. Your PC needs both.

Alan Stainer