flipper wrote:
On Mon, 27 Aug 2007 19:47:27 -0600, Donald
wrote:


macarty wrote:

hi, join as solder or use some kind board where i can use two micro sd
memory for my mp3 player or phone.

Ok, lets think this through.


Two chips are now in the "same socket as one".

A command is issued to the "one" chip.

Which chip should respond ?

Both will try to respond, both will be in the same address space.

So, no you can _not_ solder two chips together and expect the device to
know what you have done.

I am not sure why this is not obvious to the casual observer.


Are you basing the 'obviousness' of your conclusion on your intimate
knowledge of the SD interface? Because, if so, that obviates the

Yes, I would agree with your statement in principle.

However, I did ask twice as to the nature of this "joining".

And the Op did state above,"join as solder or use some kind board where
i can use two micro sd memory for my mp3 player or phone."

So, your assertion is not correct.

The OP wants to push two devices into one slot.

This is the obvious I was trying to get at.

So, if the OP is still reading any of this, I hope he did learn
something and will be willing to do a little more homework as to
understanding this brave new world.

donald

Flipper: Good response, got me thinking on how to answer the OP.

generic 'obviousness' of it and, in the generic, what he describes as
the basic goal is done every day; it's called "chip select." And, in
fact, SD supports SPI which, surprise, has chip select.

Chip select is, of course, how multiple memory sticks are addressed in
multiple slots in your everyday PC (and often on the memory stick
itself) but, to his notion of 'combining', I have some very old boards
that were once used to hold multiple sticks so they could be plugged
into one PC slot.

And, btw, there were chips made with inverted chip select lines so you
could, literally, "solder two chips together" and have it work.

That doesn't mean the idea will work with his MP3 player because, as
the saying goes, the devil is in the details but it's by no means
"obvious to the casual observer" that the general idea could never
work.


donald