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From: ford@crash.CTS.COM (Michael Ditto)
Newsgroups: comp.sys.amiga
Subject: Re: 80 track 5.25" drive help needed!
Message-ID: <1307@crash.CTS.COM>
Date: Tue, 30-Jun-87 12:45:48 EDT
Article-I.D.: crash.1307
Posted: Tue Jun 30 12:45:48 1987
Date-Received: Thu, 2-Jul-87 00:45:38 EDT
References: <383@esunix.UUCP>
Reply-To: ford@crash.CTS.COM (Michael Ditto)
Organization: Crash TS, El Cajon, CA
Lines: 42
Keywords: df2: 80 track 5.25 SOS

In article <383@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes:
>I need help with getting a 5.25" drive to format to 80 tracks under
>AmigaDOS.
>
>I've successfully adapted a Teac FD-55-FV (DS-DD, 80 track) to my Amiga
>using information previously posted here and elsewhere, But I still have
>some problems.
>
>1) I cannot format to 80 tracks.  [...]

Changing the devs:MountList to have HighCyl=79 should fix this.

>2) The diskchange signal is not being read by the Amiga.  [...]
>
>3) The head load solenoid on the Teac loads and unloads with every track
>   change.  [...]

On an Amiga external disk drive (3 or 5") there is a small extra circuit
board, usually done with two pals.  This circuit performs three functions:

1)	It supports an "ID Mode" in which it indicates that a drive is
	present, and its type.  This is done serially with the MTRX and
	READY lines.

2)	It latches the motor status and remembers it when the drive is not
	selected.  This allows the Amiga to control each drive's motor
	independently.

3)	It latches the disk-change signal, resetting it only on a motor
	step pulse.  This allows the Amiga to always find out about disk
	changes even if they happen when that drive was not selected.  It
	also is the reason for the "clicking" of empty drives.

All of this information is documented in the "Schematics and Expantion
specifications" document available from Commodore.  You will need this
information in order to build the needed circuit.  It may be possible to
order the small circuit board from Commodore.
-- 

Michael "Ford" Ditto				-=] Ford [=-
P.O. Box 1721					ford@crash.CTS.COM
Bonita, CA 92002				ford%oz@prep.mit.ai.edu