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From: dgold@apple.UUCP
Newsgroups: comp.sys.mac
Subject: Re: Serial drivers question and ROM differences
Message-ID: <913@apple.UUCP>
Date: Wed, 3-Jun-87 12:26:21 EDT
Article-I.D.: apple.913
Posted: Wed Jun  3 12:26:21 1987
Date-Received: Sat, 6-Jun-87 04:04:04 EDT
References: <56@sickkids.UUCP>
Reply-To: dgold@apple.UUCP (David Goldsmith)
Organization: Apple Computer Inc., Cupertino, USA
Lines: 35

In article <56@sickkids.UUCP> daniel@sickkids.UUCP (Daniel Guerin ) writes:
>1) IM (the original edition) says that the ROM serial driver does not support
>handshake;  however, on both a 512E and an SE the ROM driver *does* Xon/Xoff
>handshaking (I can see it on my breakout box) on at least the modem port (I
>have not tried with the printer port).  Of course I do enable Xon/Xoff
>with a SerHShake call.  I looked through the documentation, and although TN #57
>says that SERD 0 is in the 128K ROMs, it does not say that the ROM and the
>RAM serial drivers are the same.  Is RAMSDOpen just a no-op with the 128K and
>SE ROMs?  Should it still be called for compatibility with the 64K ROMs?
>
>2) When I close a serial driver with CloseDriver, DTR (Handshake out, pin 1 on
>the mini-8 connector) drops on an SE, but *remains asserted* on a 512E.  Is
>this behaviour normal?  Is there a way to keep DTR asserted on the SE other
>than by not closing the driver?  I also tried to call RAMSDOpen/RAMSDClose,
>and the behaviour is the same: RAMSDClose causes DTR to drop on the SE only.

On everything except the 64K ROMs, the RAM and ROM serial drivers are the
same, and RAMSDOpen does nothing.  You should still call RAMSDOpen if you
want your application to be compatible with the 64K ROMs.  You should
also call RAMSDClose if you call RAMSDOpen.

For information on all of this, and how to keep DTR asserted (I believe the
difference between the 512E and the SE is related to the serial port
hardware; I think the Plus works the same as the SE), read the Serial
Driver chapter of Inside Mac volume 4.

-- 
David Goldsmith
Apple Computer, Inc.
MacApp Group

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