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From: fiddler%concertina@Sun.COM (Steve Hix)
Newsgroups: comp.sys.apple
Subject: Re: upgrading an old rom //c
Message-ID: <32632@sun.uucp>
Date: Mon, 2-Nov-87 14:20:02 EST
Article-I.D.: sun.32632
Posted: Mon Nov  2 14:20:02 1987
Date-Received: Thu, 5-Nov-87 23:41:45 EST
References: <3038@husc6.UUCP> <282@n8emr.UUCP> <174@dalcsug.UUCP>
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In article <174@dalcsug.UUCP>, mackay@dalcsug.UUCP (Daniel MacKay) writes:
> 
> If you press control-reset on a //c with the new ROM, to get to ROM 
> BASIC, then type PR#7<ret>, you get a message "Appletalk Offline".
> 
> This is sort of interesting, because, of course, PR#7 normally means
> "Boot from the device found in slot 7".  Disregarding the fact that the
> //c has no slots whatsoever, it indicates that the guys who put the
> new ROM together were thinking of AppleTalk.
> 
> Incidentally, if you do this on a //c with the OLD ROM, the machine
> will boot from the external drive instead of the internal drive-
> can come in handy if your internal drive dies one day.
> 
> Anyone know what the message means?

Yes.  (Some of this is a little fuzzy in my mind, it's been a
while.)  Early in '85, some bug fixes and enhancements to the
//c ROM were made.  Most important was code to support use of
external drives other than the disk//c, specifically the UniDisk3.5
(a dumb name, I thought at the time, and still do).  Support
for daisy-chaining  drives though a "protocol converter" was
added, and one of the programmers involved in this saw that they
could also fit the required foundation to suport AppleTalk.

So they put it in.  Nobody (least of all Apple) has ever built
the required hardware (a converter box) to connect any AppleTalk
devices to the //c, but the ROM code to support it is there.

Because they never expected to officially support such a device,
I was told to not document the feature in the "Apple //c Techinical
Reference Manual" that was published in late 1985.  I always
expected that someone (lots of 'em) would notice this interesting
message and get curious.  If you get the //c tech ref., you can
look at the ROM listing in it and see what the code does.

I think that there is now another way to boot off an external
drive, but I can't remember what it is now.  Should be in the
manual.

	seh