W dniu 2011-01-26 12:04, Michoo pisze:
> W dniu 25.01.2011 15:53, Andgro pisze:
>> Jeśli na karcie jest napisane class 6, to znaczy że MINIMALNY transfer w
>> dowolną stronę na całej przestrzeni karty nie może być mniejszy niż
>> 6MB/s. Bo to właśnie dokładnie oznacza "class 6".
> SD Physical Layer Simplified Specification Version 2.00
>
> 4.13.6 Speed Class Definition
>
> Tam jest taka ładna krzywa dla %RU zajętych w AU. Starczy zaaplikować ją
> dla %RU zajętych na całej karcie i już twój usecase zaczyna "być
> prawidłowy".

"
Class ratings measure the minimum sustained speed required for recording
an even rate of video onto the card. The class rating number corresponds
to the transfer rate measured in megabytes per second. Class 2 cards are
designed for a minimum sustained transfer rate of 2 megabytes per second
(MB/s)1, while Class 10 cards are designed for a minimum sustained
transfer rate of 10MB/s2.

Speed Class is a minimum speed based on a worst case scenario test. The
Speed Class is important for video mode or camcorders, where the device
is actually saving a steady stream of data. The resolution and format of
the video determines the amount of steady stream data. This translates
to a minimum speed you need to guarantee that the video captured on the
cards is recorded at an even, sustained rate with no dropped frames
(which typically results in lost data and choppy playback).
"

Źródło: sandisk.com (SanDisk obok Toshiby i Panasonica jest członkiem
założycielskim SD Card Association)

"
3.4 Speed Class
Four Speed Classes are defined and indicate minimum performance of the cards
o Class 0 - These class cards do not specify performance. It includes
all the legacy cards prior to
this specification, regardless of its performance
o Class 2 - Are more than or equal to 2 MB/sec performance.
o Class 4 - Are more than or equal to 4 MB/sec performance.
o Class 6 - Are more than or equal to 6 MB/sec performance.
High Capacity SD Memory Cards shall support Speed Class Specification
and have performance more
than or equal to Class 2.
Note that the unit of performance [MB/sec] indicates 1000x1000
[Byte/sec] while the unit of data size
[MB] indicates 1024x1024 [Byte]. This is because the maximum SD Bus
speed is specified by the
maximum SD clock frequency (25 [MB/sec] = 25000000 [Byte/sec] at 50 MHz)
and data size is based
on memory boundary (power of 2).
"

Źródło: Physical Layer Simplified Specification Version 2.00

Krzywa o której mówisz nie dotyczy moich "pretensji". Program testujący
robi zapis do konkretnego adresu a reszta pamięci karty jest wolna. Więc
program pokazuje transfer do danego adresu dla r=0.

Tu sa wyniki testów kart Adata:
[url=http://agrotronik.wrzuta.pl/obraz/9Spadds9w5V/a
data_16resultrange][img=http://c13.wrzuta.pl/wm2765/
ca671df1000c6d2b4d408215/adata_16resultrange?][/url]
[url=http://agrotronik.wrzuta.pl/obraz/3LIJ88WPPb9/a
data_8resultrange][img=http://c4.wrzuta.pl/wm4862/3e
22fe15001ce6af4d408216/adata_8resultrange?][/url]

--

Pozdrawiam,

A. Grodecki

"Wszystkie zwierzęta są równe.
Ale te, które mają futerko w trójkolorowe pasy, są równiejsze."