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Old 14 December 2008, 17:30   #6
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Join Date: Jan 2004
Location: Oxford
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Originally Posted by Andymiga View Post
Now, about the MaxTransfer value ... I've read the following: 0x1fe0, 0x1fe00, 0x1fe000, 0x1fe0000 (among others, but the ones with "1fe" are the most common on the forum). What is the correct value?
AFAIK there is no true correct values but IDE devices, particularly CF cards, are susceptible to corruption if the value is set too high.

The most regularly supported maximum transfer sizes in IDE are either : 128Kbytes or 64Kbytes. By specifying a max transfer just below either of these two almost guarantees compatibility. The lower it is, the less data is transferred in a single command. Not that big a deal from a performance point of view.

128K-1 = 0x1FFFF
64K-1 = 0xFFFF

So people have been recommending 0x1FE00 and 0xFE00 as being close to these magic 128k and 64k limits. Why they don't recommend the limits I dunno. Where the other strange values came from, again I dunno (they didn't work for me, 0xFFFE was the largest I could use).

You have to try one and see what works well for you. You know fairly soon on if you have the wrong values. You get CRC errors all the time.
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