What is the Basic purpose of RAM

[harmonSmith]

He guys, I am a beginner in computer science. My question is about RAM. I think the main purpose of RAM is to temporally save running programs. What are the other purpose of RAM. Can it increases the functionality of Graphic cards.

[chitrangda]

http://en.wikipedia.org/wiki/Random-access_memory

[insane_alien]

Some graphics cards use the system RAM but those are generally the less powerful and integrated graphics chips rather than a seperate card.

 

but the only purpose it serves across all PC's is as a fast cache so it doesn't have to read/write from the really really slow harddrive.

 

Bookworm: try being helpful and interact with other users not just fob them off on a link to wikipedia.

[chitrangda]

Some graphics cards use the system RAM but those are generally the less powerful and integrated graphics chips rather than a seperate card.

 

but the only purpose it serves across all PC's is as a fast cache so it doesn't have to read/write from the really really slow harddrive.

 

Bookworm: try being helpful and interact with other users not just fob them off on a link to wikipedia.

i will try my best to do so from now.

[bascule]

RAM is where every program that's running on your computer (including the operating system kernel) lives

[Pangloss]

That's the best straight-up definition, above. It's not so much that programs are "temporarily saved" there, as it is that programs reside in that space as they are being called for instructions by the CPU, because it's faster than calling for those instructions off the hard drive. Of course, many programs are too large to fit entirely in RAM, so often programs are modularized and only the module you're working on is loaded into RAM at a given time, and then when another module is needed it's loaded from the HD into the RAM.

[Dudde]

some of the processes that video card RAM takes over really helps take the strain off the generic system ram, so it doesn't take forever to run it's regular tasks mixed in with the graphics algorithms. That's why I've always hated integrated graphics

 

I like insane_aliens definition of RAM for the question defined, with a good finish by pangloss!

[big314mp]

To throw in one more point, increasing the video RAM increases the amount of data that the video card can work with. In the most straight forward sense, you can run a higher resolution as there is more space for the increased data.

 

In the real world this can be seen in products such as the 9800GTX vs the 8800GTX. At ultra high resolutions (2560x1600), the 8800 will beat the 9800 because the 8800 has 50% more RAM. In a real sense, frames that large don't fit in the 9800's memory, causing it to have to access system memory, which is painfully slow.

[insane_alien]

A 2560x1600 frame in 32 bit colour is 16.384MB.

 

are you seriously telling me that a modern graphics card does not have 16.384MB of RAM?

 

here is the calculation to back me up here.

 

2560x1600 = 4096000 pixels *32 bit per pixel = 131072000 bits /8 = 16384000byte / 1000000 byte/MB = 16.384MB

 

although RAM is one of those things that still uses a binary mega byte. so i suppose it should really be 15.625 MiB

[Dudde]

Well, when you overload the graphics card and force it to access the system memory somehow, say - by building a jiggly ball in 3D-Studio max! It doesn't matter how you do it, just that you do it. Once that happens, even the system memory should be able to help it out, but the BUS that the information travels across is usually the bottlenecking point.

[big314mp]

you can't just take the size of the actual frame, as you have to take into account the amount of math and data used to generate said frame.

 

There is a lot of data that the gfx card has to process to produce even one frame. The primary RAM hog is texture data. Virtually all of the video game textures need to be stored on the card, so data that isn't even being displayed is being stored on the card for fast access.

 

And then you have to throw in effects such as anti aliasing which cause the frame that is rendered to be 2-16 times as large (albeit unoptimized, but AA causes HUGE performance hits in video games).

 

The amount of memory that is used quickly spirals upward. Granted, high end video cards with 512MB+ video RAM rarely run into problems such as this, but the effect can be shown (I'm looking for the video card review that I saw it best in, if I find it, I'll post it).

 

http://enthusiast.hardocp.com/article.html?art=MTQ4OSw5LCxoZW50aHVzaWFzdA==

 

The CoD4 section relates to what I was referring to.

 

http://enthusiast.hardocp.com/article.html?art=MTQ4OSw0LCxoZW50aHVzaWFzdA==

 

The specific page.

Edited August 30, 2008 by big314mp
grammar/clarity