Question For All You Pro Tools Hd Users Out There Options

[slowintrepid]

k so I fully understand everything about PT LE and other DAW's but HD rigs really boggle my mind, mainly the whole DSP/Interface part. so here goes.

so I know to get started with a HD riig you need two things

1. the DSP Core and an Interface (96 I/O and 192 I/O)
and
2. a Ton of money.

but here are a few things I dont understand.

1. how does Digi guarantee support for up to like 192 and 96 channels of I/O (HD|3 Accel of course) and does it guarantee that in other programs that support TDM like Digital Performer, Nuendo and Logic? or is it just plug-in DSP in those programs?

2. on the interfaces there is the 96 I/O and the 192 I/O but on the 192 I/O I don't see any typical TRS inputs I just see tiny hole that says 1a 1b through 8a 8b
I can't see that well in the picture http://www.digidesign.com/products/hd/syst.../192enlarge.jpg does that mean there is a separate I/O box or somthing for that unit.

3. whats the deal with the "Sync I/O" box, no idea what that thing does.

4. on the "system diagram" they them using an external scsi drive, is that nessecary for the high track counts, or can you get by with just a fast firewire drive.

is there a difference between using HD gear with Pro Tools, than with Digital Performer, Logic and Nuendo or do you get the same performance and everything?

and finally.

are there any other companys that make DSP cards and I/O interfaces similar to an HD rig? (like RME or Metric Halo I don't know if they're similar)

thanks alot
SIntrepid