Path: utzoo!mnetor!uunet!husc6!rutgers!meccts!meccsd!rms
From: rms@meccsd.MECC.MN.ORG (Roger M. Shimada)
Newsgroups: comp.sys.apple
Subject: Re: Unidisk 3.5/Apple 3.5
Message-ID: <814@meccsd.MECC.MN.ORG>
Date: 13 Dec 87 22:59:57 GMT
References: <8712100517.AA04037@crash.cts.com> <17275@bu-cs.BU.EDU> <486@PT.CS.CMU.EDU>
Reply-To: rms@meccsd.UUCP (Roger M. Shimada)
Organization: Minn. Educ. Comp. Corp.
Lines: 26

In article <486@PT.CS.CMU.EDU> ralphw@IUS2.CS.CMU.EDU (Ralph Hyre) writes:
>...
>Has anybody hacked their LIRON card to make it possible to daisy chain any
>Apple drive (both the 5.25 and 'dumb' 3.5's, in particular) to the back of
>a //e-based UniDisk 3.5?  I'm not excited about disassembling the ROM and
>figuring out how to uncripple it and make it look like the //c protocol
>converter code, particularly. And of course, just replacing the EPROM is
>hard because Apple didn't use a socket. Grrh!

You can daisy chain a 5.25 drive off a Liron card right now.  I tried
it.  The problem is using it; you can if you're running DOS 3.3, but
then you can't normally use the 3.5.  Alternatively, under ProDOS you
can use the 3.5 normally but would have to rig some patch to use the
daisy chained 5.25.

I don't think it's possible to do an EPROM that could talk to both a
Unidisk 3.5 and a Disk 3.5.  Not enough space for the code, much less
for the data area needed.  (The Disk 3.5 is not much different than
a 5.25.  For instance, you would need the disk byte lookup tables from
the 5.25 device driver, as well as its data buffer.)

Any //c reference manual won't help you with talking to a Disk 3.5;
the only // series machine that talks to them is the gs.

--
Roger M. Shimada		ihnp4!meccts!rms	rms@MECC.MN.ORG