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From: nparker@cie.uoregon.edu (Neil Parker)
Newsgroups: comp.sys.apple2
Subject: Re: How does Eject work on an Apple 3.5 drive?
Date: 8 Jan 1993 04:09:40 GMT
Organization: The Universal Society for the Prevention of Reality
Lines: 34
Message-ID: <1iiuq4INNhne@pith.uoregon.edu>
References: <1993Jan2.061850.8141@cs.uow.edu.au>
NNTP-Posting-Host: cie.uoregon.edu
In article <1993Jan2.061850.8141@cs.uow.edu.au> david@cs.uow.edu.au (David E A Wilson) writes:
>I have looked at the IWM pinout description in tn-misc-006 and read
>descriptions of the 5.25" disk drive, Unidisk 3.5 Smartport and everything
>else I could find but have never been able to find out what the controller
>does to cause an Apple 3.5 to eject. The only additional signal the 3.5
>has over the 5.25 is the head select. How then can the drive be told to
>eject the disk?
As a previous poster noted, it's done by setting the phase lines to a weird
combination. Here are the exact instructions:
Get the byte at $C031. Turn bit 6 ON, and bit 7 OFF. Don't change
any other bits. Write the modified byte back to $C031.
Turn on the drive by accessing $C0E9.
Select the eject function by accessing $C0E1, $C0E3, and $C0E5.
Perform the eject function by accessing $C0E7 and then $C0E6.
When the disk is ejected (it takes about 1 second), turn the drive off
by accessing $C0E8.
Clear the control lines by accessing $C0E0, $C0E2, and $C0E4.
Finally, get the byte at $C031, turn off bit 6, and write it back.
Note: Just in case there are any typos in the above, DON'T try it with a
non-expendable disk in the drive.
The full details of this trick and many others can be obtained by anonymous
FTP from cco.caltech.edu. Cd to /pub/apple2/info and get the file
"iwmstuff". If you can't do anonymous FTP, I can provide copies by
e-mail.
- Neil Parker
--
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