The Skinny on UDMA Cards & Speeds (Memory Cards)

[Princess-Kaveshla]

Forum Storage and Media
Subject The Skinny on UDMA Cards and Speeds
Posted by matchoo5050
Date/Time 14:58:07, 14 February 2008 (GMT)


Guys there is mass-confusion in the market regarding what is and what is not a UDMA memory card and the speeds at which they are rated at.
I am going to help explain it so you don't get bamboozled.

Ok the X = 150KB/sec as most of you know this is supposed to represent the Write Speed of the card but in many cases manufacturers (I will not name names) are using the read speeds only or a combination of the read speed + write speed / 2. Ok knowing this you must ask or look for the Read and Write Speed in MB/sec in the specs if they are not listed beware and if they are you can determine the real X speed by taking the MB/sec Write * 1000 / 150.

What is UDMA? UDMA stands for Ultra Direct Memory Access and in essence it is twice as fast as DMA mode. There are different modes and speeds of UDMA. UDMA mode 4 has been described as the mode adopted by most camera manufacturers this allows for a maximum transfer rate of 45/MBsec or 300X Write and 60MB/sec or 400X Read.

What is a UDMA card? A UDMA card is a card that offers Ultra DMA on both read and write side of the flash. Many companies are claiming to offer UDMA memory cards when in fact they are only offering UDMA enabled memory cards these cards allow UDMA operation on the read side. This is very important for the photographers that are now buying memory for the new UDMA cameras. If the write side of the card is not UDMA then your new UDMA camera will not work any faster than your old one did writing images to the flash.
What to look for when buying a true UDMA memory card?

#1 High price any UDMA card that is not 2-3 times the price of a DMA/UDMA enabled equivalent MB/GB size card is not true UDMA. One of the least expensive true UDMA memory cards on the market is the Transcend 266X line and in my testing is actually faster than the Lexar 300X UDMA cards on my test machine. For reference an 8GB Transcend UDMA 266X memory card runs around $125 while you can find many UDMA Enabled 8GB cards on the market for around $50.

#2 All true UDMA cards that I know of are SLC (single layer cell) flash. So ask for SLC.

Now knowing what a true UDMA card is and how to spot one what is a UDMA Enabled card good for?

If all you care about is getting the information from the card to your computer super fast then it is for you but, you will have to upgrade to a UDMA Compact Flash card reader. While there are not many choices at this time and cost seems to be high you can find great quality UDMA USB2.0 card readers in Single Slot and All-in-1 formats for a very good price. I have a test located at the link below that outlines a few of them.
http://www.mydigitaldiscount.com/WSWrapper.jsp?mypage=StoreProductTesting.htm

I hope this helps many of you out that are kinda new and looking for a flash card that will work with the standards you need.
Matt Dawson
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