Memory vs RAM
 

I use the command free -mt because I want to know the amount of RAM that I have.

However, it only shows me my memory. What is the difference between memory and RAM as I need my RAM.

Its the same.
free -m, shows the memory is MB, you can use -g option also for GB.
Also, you can check /proc/meminfo for more information about your memory.

RAM is memory. ;)

The reason why you normally have less 'memory' than RAM is because some RAM can be used for onboard devices (video uses the most, but even networking, sound, etc. will use some RAM) and there is normally some reserved for 'system' use.

To see how much physical RAM is installed, I either check the hardware, or use lshw. BTW, if you use lshw, make sure you run it as su/sudo, it returns less information if run as a normal user.

This is my lshw output (edited to only the 'memory' output)-

So I have 2 x 2GB sticks for 4GB in total.

In that case, why is there the term random access memory instead of just memory ?

what the hell is this ?

c@c-laptop:~/bash_folder$ lshw | grep memory
WARNING: you should run this program as super-user.
*-memory
description: System memory
resources: irq:16 memory:58280000-582fffff ioport:60f0(size=8) memory:40000000-4fffffff(prefetchable) memory:58300000-5833ffff
resources: memory:58200000-5827ffff
resources: irq:16 memory:58340000-58343fff
resources: irq:24 ioport:5000(size=4096) memory:57100000-581fffff ioport:50000000(size=16777216)
resources: irq:16 memory:57100000-5710ffff
resources: irq:25 ioport:4000(size=4096) memory:56100000-570fffff ioport:51000000(size=16777216)
resources: irq:26 ioport:2000(size=8192) memory:55000000-560fffff ioport:52000000(size=16777216)
resources: irq:29 memory:55000000-5503ffff ioport:2000(size=128)
resources: irq:27 ioport:1000(size=4096) memory:54000000-54ffffff ioport:53000000(size=16777216)
resources: irq:16 memory:58344400-583447ff
resources: irq:28 ioport:60d8(size=8) ioport:60fc(size=4) ioport:60d0(size=8) ioport:60f8(size=4) ioport:6020(size=16) memory:58344000-583443ff

I got another question.

If I type lshw | grep memory , the lshw will run all over again whenever I reenter the command. How do I prevent the "all over" from occuring again?

Because there is also ROM (read only memory).

Just use lshw.

There is some way to remove the rest of the output from lshw and only get the memory section, but I dont know the command offhand.

Its not that hard to just scroll though the info you dont want to get the memory bit. ;)

In that case, how do I know if it is RAM or ROM if I see memory?

If its in the lshw output, its RAM.

ROM is used in lots of places, but it shouldnt show up as 'memory' in lshw.

http://en.wikipedia.org/wiki/Read-only_memory

There can be many different hardware devices that are considered memory i.e. system memory, Hard drive, tape drive, CDROM/DVD etc. Typically when one talks about RAM it means system memory.

In a nutshell devices like the ethernet controller or video adapter use resources i.e IRQ - interrupt request, I/O port addresses and Memory Address. This is how the processor talks to the device.

BTW RAM - Random Access Memory is a type of integrated circuit. There are two main types of RAM dynamic and static. The type used in most PCs is dynamic RAM.

http://duartes.org/gustavo/blog/post...ets-memory-map

Errr can anyone explain the garbage I am seeing?

you are looking at irqs as well as hexadecimal representations of physical 'memory' addresses that are accessed by hardware drivers when talking to devices.