Andrew Rossmann said:
[This followup was posted to alt.comp.periphs.videocards.ati and a copy
was sent to the cited author.]
Hello,
I am just looking for some advice. I am looking for a new directx9
compatible card, yet I am seeing that a lot of cards on the market are
'DDR'. Am I right to assume that DDR means that the video card is
slaving system resources from the computer, i.e. it doesn't have it's
own ram?
I don't like this idea, and would prefer to avoid this. Can anyone
recommend a card that has it's own memory and is DX9 compatible?
Is the ATI Radeon 9600 Pro 128MG a card I should be looking at?
Add-in video cards do NOT use your system RAM. The only video that uses
system RAM are those that are built into chipsets.
DDR is just the type of RAM used by the video card. DDR is one of the
fastest right now. Before, they used to use SDRAM, plain RAM, VRAM, WRAM,
and all sorts of oddball variations.
DDR = SDRAM!!!
The proper terminology is DDR SDRAM or SDR SDRAM.
The terms mean respectivly:
Double Data Rate Synchronous Dynamic Random Access Memory and
Single Data Rate Synchronous Dynamic Random Access Memory
SDR SDRAM is also refered to as PC66, PC100 and PC133 memory. Whereby the
last two were the most popular. DDR is commonly refered to as PC2100, PC2700
and PC3200 memory. Further explanation can be found on the web as far as
these PC-numbers is concerned.
What is 'plain RAM'? Perhaps you are refering to various forms of DRAM like
EDO DRAM or do you mean SRAM (whereby DRAM=Dynamic Random Access Memory and
SRAM=Static Random Access Memory)
VRAM is special VIDEO RAM designed to work with graphic processors
(videocards) and has nothing to do with system memory (although sometimes
DRAM has been used instead of the faster and more expensive VRAM). WRAM
(Windows RAM) is very similar as VRAM and is also developped for video
cards.
Anyway to the original poster. As been said above add-in videocards have
their own memory chips soldered onto the cards. Although the AGP
specifications allow videocards to use system memory for its use (e.g. as
texture buffers etc.) this is not used as modern video cards have more than
sufficient memory onboard to keep all GFX-intensive calculations and memory
manipulations on the card itself. Nowadays VGA-cards don't use VRAM chips
anymore but more conventional SDRAM-chips. The DDR means that they use
Double Data rate memory chips instead of the Single Data Rate variant.
I guess what the original poster meant with video-chips that also use a part
of the system memory as its frame buffer is: Shared Memory Buffer
Architecture (SMBA) or Unified Memory Architecture (UMA). Especially SGI
uses the latter term. Intel nowadays refers to SMBA with a new term called
Dynamic Video Memory Technology (DVMT). These use whatever memory types are
on the mainboard (nowadays SDR or DDR SDRAM) hence the confusion.
Hope this helps,
Regards,
Manu T
