[rescue] Vaxen?

[Scott Newell]

At 04:07 PM 4/27/2002 -0400, Joshua D Boyd wrote:
>
>Well, yes, but not as bad a 30 pin stuff.  I was just thinking that 72pins
>might be something I could do (maybe), but 168pins would definately require
>a lot more skill than I could make up on the spot.

Aren't most 168 pin simms actually sdram?  From what I've seen, sdram
interfacing is a little more involved than plain old dram.  Might not be
too bad--I'll have to dig up that issue of CCI...


>> Circuit design wouldn't be the problem--I'd be more concerned about the
>> firmware required to handle all the SCSI commands and transactions.  And do
>> it quickly!
>
>As I believe Dave pointed out, chips are available that take care of that
>for you.

Just read the NatSemi datasheets and app notes--the chip mentioned appears
to handle handshaking, and it will do DMA, but that's about it.  You've
still got to have a buffer.  And let's not forget you'd like this box to
look like a drive.


Actually, this whole SCSI target thing is interesting...I've whined before
about the inability to get a handful of fast discrete digital I/O lines
from my sparcs (something like the parallel printer port on a PC can be
_very_ handy for testing embedded hardware projects).  Maybe SCSI targets
are the way to go--build a box that's got a SCSI address and send commands
to flip and read bits.  Hmm.


newell