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- Laptop Internal SD Reader is SLOOOOW???
July 28, 2006, 2:28 am
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When I plug in an 80X SD card, it reads at 700KB/S.
And it kicks up the speedstep to max so you can dry
your hair from the hot air coming out of the fan.
If I constrain the Processor speed to 600MHz, the
read performance is the same.
IF I plug the same card into a USB2 card reader into
the same machine, the read speed is 8000KB/S with
little processor load.
Write speeds are similarly affected, though I've not
done careful measurements on writes.
I loaded the drivers that came with the machine.
WBSD.sys is v2.0.2003.320.
Couldn't find anything newer on the web.
Guessing from the idstring, looks like a Winbond
W83L518 chip. The datasheet doesn't have ANY
timing info at all.
Can't use a Cardbus adapter, cause the took out
the second cardbus slot to put in the SD slot.
Any way I can get acceptable performance out of the
internal SD slot?
Re: Laptop Internal SD Reader is SLOOOOW???
Sounds like a braindead driver that sits there busy-waiting for
transfers to finish, coupled with slow firmware in the card-reader IC
[these parts are typically an 8051 microcontroller with some custom
firmware in them]. Having designed Winbond parts into many applications
and dealt with their technical documentation, application notes and
other developer support, I wouldn't hold out a lot of hope that this
will get fixed :)
Just out of interest, how is the card-reader connected to the mainboard
- is it an internally connected USB1.1 device, by any chance? If so,
you'll never see USB2 performance out of it.