SCSI to IDE
Alexandre Souza - Listas
pu1bzz.listas at gmail.com
Sat Dec 4 14:50:26 CST 2010
> If reading speed was an issue, one could employ the faster 4-bit
> access to SD rather than the simpler and much slower SPI mode that's
> usually used for slow embedded applications.
Hey people, c'mon?!
SD Card speeds:
Speed Class Rating
The Speed Class Rating is the official unit of speed measurement for SD
Cards, defined by the SD Association. The Class number represents a multiple
of 8 Mb/s (1 MB/s), and meets the least sustained write speeds for a card in
a fragmented state.
These are the ratings of some currently available cards:
a.. Class 0 cards do not specify performance, which includes all legacy
cards prior to class specifications.
b.. Class 2, 2 MB/s, slowest for SDHC cards.
c.. Class 4, 4 MB/s.
d.. Class 6, 6 MB/s.
e.. Class 10, 10 MB/s.
Ok, now to SCSI specs
Fast SCSI: 10MB/s
Fast-Wide SCSI: 10MB/s
Ultra SCSI: 20MB/s
Ultra-Wide SCSI: 40MB/s
- I hope I can develop a SCSI bridge that can move 10MB/s, because I
doubt a normal Atmel XMega will be capable of that.
- If I can design a fast enough circuit, I can use a Class 10 card and
will have 10MB/s.
- Since it will be a hard disk emulator, and not a SD Card reader, I can
have TWO interleaved cards on the bridge, so making 20MB/s easy
- We are talking old computers here. What do you use about CLASSIC
computing that goes beyond Fast-Wide SCSI?
- Not all people are capable of begin big.
- Maybe with ARM microcontrollers, Ultra2Wide can be achived. Who knows?
Time to define DOWN TO EARTH specs and begin working :)
Greetings from Brazil,
More information about the cctalk