>Well, the cables work fine for printers, MIDI interfaces, etc.  I tried
>booting the PowerBook into MacOS, using FreePPP to connect to the MkLinux
>box and its stats reported bad frames, too, though I tested FreePPP at
>57,600, so the results were more dramatic (like 30+ seconds to connect to
>the computer at the other end of the link by telnet....)
>
>So that pretty much means that it's not the NetBSD driver, or at least
>that it's not _just_ the NetBSD driver.  I assume the MacOS serial driver
>_does_ tell the other end to wait....  :-)  So it looks like Linux ignores
>it even when it does.  Hmmm.

David,

It's been a couple of years since I looked at some of this, but as I 
recall InterSLIP on MacOS only used CTS for flow control (in-bound to the 
Mac I think), and all variants of PPP at the time used RTS for flow 
control (out-bound from the Mac).  Someplace I've got a memo from Amanda 
Walker (InterSLIP author at Intercon) on this subject.  That's the reason 
that most modems need to be configured to not use DTR for hangup control 
under PPP but can use it under SLIP. Recall that most (not all) hardware 
handshake modem cables sold nowdays have RTS tied to DTR.  If all this is 
still true then it might be that your problem is you're only getting flow 
control in one direction.

-bob