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Unlocking Prodos 800K floppies on Mac OS9.1

HyperGuy

New Member
Joined
Apr 9, 2013
Messages
7
Location
Ingham County Michigan
Hello All,

I have archived some Basic programs from 800K Prodos discs to my Mac Performa running OS 9.1.
The copying went OK. But, I cannot write to, erase, initialize nor reformat the 800K disc while in the
Mac performa. The message is that the disk is Locked. There is no visible check box when "Getting Info".
The notch in the corner is closed. No asterisk appears before any file when 'CAT" is typed while the disc
is in the IIGS.
How can I "Unlock" the 800K Prodos disc to write data to it using the Mac? Can anyone help solve this
dilemma?

Thank you.
The HyperGuy
 
I'm not sure I understand completely how you got this disk in the first place. Did the Performa, running OS 9.1, write this disk originally? [Working theory: Mac OS 9.1 can't write to ProDOS filesytems; untested by me]
 
I don't think Apple removed the ability to write to ProDOS disks in OS9. I know that turning on personal file sharing interferes with the ability to mount the disks, but it sounds like they are mounting ok. PowerPC Macs tend to be a crapshot at using 800k disks. The Mitsubishi drives they came with were lousy compared to the Sonys.
 
That's true about the quality of the drives. I rely on DiskDup+ as the only thing that can reliably work the drive in a classic Mac.
 
I have read and wrote file-by-file and diskcopy imaged ProDOS 800k, MS-DOS 720k/1.44m, and Mac 800k/1.44m all on my Beige G3 all with no problems, however I am running 9.0.4. So I can tell you some versions of OS9 are compatible, but maybe support was removed in 9.1, I can't speak to that.

EDIT: I did forget to mention ProDOS/MS-DOS translator will NOT run/work if you have "File Sharing" enabled, so maybe you are hitting that limitation, but I kind of doubt it, because a big dialog will pop up telling you such if you insert a disk when its enabled.
 
Last edited:
David,
The 800K discs were formatted and written to using the IIGS (ROM 3). This was my teaching machine for Physics
and Physical Science classes. Interfacing temperature, timer, sound frequency, etc. written in BASIC.
Yes, the Power PC Mac reads the disk and allows copying the files, but cannot write to this disc. A lock icon appears
when the disk is opened to display its files. At a loss as to how to go about unlocking it.
 
Is the disk WP tab slid to the locked position? Or is it possible the WP detect switch is broken in your drive? Have you been able to write any other disks on that Mac?
 
It's very unlikely but possible that the disk's SOFTWARE write-protect flag has somehow gotten set — assuming, of course, that the ProDOS disk format included such a thing. I know HFS has always had one, and utilities to set and clear it existed back in the day. (The only software name I can recall off the top of my head was SoftLock, which worked great as far as I could tell — but I never tried it with anything but straight HFS.) So, how about it, IIGS experts — did ProDOS disks have a software write-protect bit stashed anywhere?
 
Very likely that this switch malfunction is the cause. I'm looking into the software write-protect flag mentioned by "gsteemso".
In the meantime I did slove the file transfer problem by connecting an Apple ADB printer cable from the OS 9.1 Mac to my Mac SE (Probably could have done this with the IIGS), and set up file sharing on both. Transfer went very efficiently. I can now place the files onto a 800 K disk on the SE and move the files to the IIGS.
Thanks for all of the tips on this forum.
 
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