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From: jdb@mordor.ARPA (John Bruner)
Newsgroups: comp.sys.mac
Subject: Re: Mac+ DTR upside down?
Message-ID: <17182@mordor.ARPA>
Date: Wed, 26-Nov-86 12:46:06 EST
Article-I.D.: mordor.17182
Posted: Wed Nov 26 12:46:06 1986
Date-Received: Wed, 26-Nov-86 20:32:28 EST
References: <1372@umd5> <6440@ut-sally.UUCP>
Reply-To: jdb@mordor.UUCP (John Bruner)
Distribution: net
Organization: S-1 Project, LLNL
Lines: 28

>						...  Uw tries to survive in a
>world where the SERD may or may not be present.  Therefore, uw probably makes
>ROM calls and gets to use the new SERD if 128K ROMs are present, but doesn't
>mind using the 64K ROMs if you don't have the new ROMs.

Well, almost.  UW tries to use the SERD driver.  It calls RAMSDOpen
first, and only if that fails does it use OpenDriver.  Just before
it exits, it calls RAMSDClose and then OpenDriver.  As Brian Powell
said, *Inside Macintosh* warns against closing the ROM serial driver
because mouse interrupts can be lost.  According to a comment in the
code, I added the call to OpenDriver after RAMSDClose because when I
left out this call, the mouse froze.  (This is Megamax's RAMSDClose,
which is (1) over a year old and (2) was outdated when I received it.)
UW v3.4 does make the hold-DTR Control call to ensure that there is no
glitch on the DTR line between the RAMSDClose and the OpenDriver, because
it is intended that users be able to exit UW, restart it, and resume a
modem-connected terminal session.

BTW, UW is in a holding pattern right now.  I've just purchased
Lightspeed C and I'm thinking seriously about MPW C.  I'm going to
convert it to one of those (I'd like to use both -- LSC for
prototyping and MPW C for final code quality, but C implementations
on the Mac don't seem to be very compatible).  I don't plan to make
any additional major changes to the Megamax version.
-- 
  John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
  MILNET: jdb@mordor [jdb@s1-c.ARPA]	(415) 422-0758
  UUCP: ...!ucbvax!decwrl!mordor!jdb 	...!seismo!mordor!jdb