Apple iic, IIc+ boot from external drive; also Unidisk 5.25"?

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Joined: Dec 2 2006
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A couple of years ago I fulfilled a bit of nostalgia & computer lust and finally got myself an Apple IIc computer! (Well, one thing lead to another and I also bought a IIc+!)

I had two questions:

1) How does one boot from an external drive?

I believe I figured this out 2 years ago, but have forgotten how! I'm wondering about it in case the internal drive fails. I tried PR#7 on the IIc and that didn't work.

2) Is there something special about the Unidisk 5.25"?

I'm asking about that because I ended up with one of them also (along with the regular Apple 5.25" drive--M0107), and have the vague recollection that I got it so that I could use it to boot externally or to daisy chain a 3.5" or some such.

Hope you vintage Apple II veterans/gurus will have some insights!

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gsmcten's picture
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Joined: Oct 4 2005
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From What I remember....

Juggler,

It has been a while since I pulled out my IIc, but all I had to do was hook up the external drive and place a disk in it. Upon startup the IIc will try the internal drive first and then go to the external looking for a disk.

Good Luck. Smile

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Steven (gsmcten)

"Apple ][.....It's ALIVE!!!!!"

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Thanks for replying-- and tes

Thanks for replying-- and testing your system! My Apple IIc doesn't work that way! It doesn't look at the external drive, but simply puts "Check Disk Drive" on the monitor.

The usual PR#7 command doesn't work either (puts one checker square and hangs).

It doesn't seem to matter which type of drive I hook up either (5.25" Apple or Unidisk or Apple 3.5"). I wonder if certain IIcs didn't do the external drive check routine--although that sounds like weird behavior for Apple IIs.

Some IIcs, the early ones, did not work with Unidisk 3.5". Here's a blurb about that: http://support.apple.com/kb/TA27890?viewlocale=en_US However, my IIc has the Revision 3 ROM and motherboard, which is a later one and can take expansion memory and work with the Unidisk 3.5". PRINT PEEK (64447) returns a 3. But that should be unrelated to external booting.

Ah, but I did find this: http://myoldmac.net/FAQ/appleIIcexisting.htm but that also implies it should boot!

Now, the controller works fine because if I boot up with WordPerfect in the internal drive and its /Work diskette in the external drive, it reads and writes to that without any problem! And knows its there! Weird, eh?

resman's picture
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Joined: Feb 9 2006
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Are you sure you have a UniDi

Are you sure you have a UniDisk 3.5 and not just a Platinum Apple 3.5 drive? A Unidisk 3.5 drive should show up in slot #5, drive #1 on the IIc, IIRC. A Platinum 3.5 won't work on a IIc. As for the UniDisk 5.25, it should show up in Slot #6, drive #2. I'm not sure you will be able to boot from an external 5.25 on a IIc. As for the IIc+, its internal 3.5 is in slot #5, drive #1 and an external 5.25 will be in slot #6, drive #1 so it can boot from an external 5.25 drive.

Dave...

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Steven, are you sure you don'

Steven, are you sure you don't have a IIc+?

I just dug up the original Apple IIc manual http://www.scribd.com/doc/200852/Apple-IIc-Reference-Manual-Volume-1-1984Apple0300814A and it implies a command is needed to do an external drive startup! See page 126 of that manual. It says that going into the Monitor via CALL -151 and then issuing 7 Control-P should work. But I can't figure out how to issue 7 Control-P! I tried sequentially, but no dice.

Dave, you've explained something well for me! The reason my IIc+ boots from the external drive so easily-- it's S6, D1!!

I also think you're right about the IIc-- that it CANNOT boot from an external drive. Hope Steven can shed some light on his success!

My 3.5" disk drive is an Apple 3.5", not a Unidisk. The model number is A9M0106.

Dave, would you happen to know what distinguishes the Unidisk 5.25" from other 5.25"? I found this http://www.vintagemacworld.com/drives.html which suggests that the only real difference is that the Unidisk doesn't work with the Macintosh LC IIe emulation card! Not a problem for my configurations!

I do get a kick out of these golden oldie computers; lots of memories and I appreciate the helpful and knowledgeable responses around here!

gsmcten's picture
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IIc External Drive Startup.....

Looks like it's a good thing I came back up this afternoon. lol

I believe that I said that I was not sure as it's been a while since I've had my c out to play with.

You may in fact be right and you have to either go in through the monitor program, dos, or the utilities program to get to the external drive.

I will have to dig out my manuals and do some research on this.

I've put all my Apple II projects on hold lately and have been working with older ( can anyone remember the Pentium 1 ) PC's. I have an XT type computer torn down to parade rest right now and I am starting to rebuid it from the motherboard up. The case wieghs a ton and there is no hard drive. Just two 5.25 floppy drives, but I digress from the topic at hand.

I will go through the books and see if I can find something useful for you. Smile

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Steven (gsmcten)

"Apple ][.....It's ALIVE!!!!!"

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Hold On To Your Hat!..........

Juggler,

OK... Here we go.

1: 1000bit.net has the Apple IIc Reference Manuals, Volumes 1 and 2
online. The address is www.1000bit.net.

You may have to jump through some hoops to get to the manuals,
but they are there.

2: Volume 1, Page 125 and 126 have what you are looking for, but in a nutshell here it is:

6.2 External Drive Startup

"The PRODOS operating system (but NOT the DOS or PASCAL operating
systems) supports startup using the external disk drive. This
PRODOS feature makes it possible to start the Apple IIc with a
diagnostic program in the event that the built in drive does
not work."

"To restart using the external drive, insert a PRODOS disk in
the external drive, then invoke the Monitor (CALL-151) and
issue 7, CONTROL-P."

That should get you where you want to go.

Whew! I knew you could do it, I just had to remember how. lol

Good Luck! Smile

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Steven (gsmcten)

"Apple ][.....It's ALIVE!!!!!"

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Steven, much thanks for the e

Steven, much thanks for the extra digging!

I mis-read your first reply in this thread... I thought that you were saying that it had been a while since you used it, but that you had tried it!

Alas, unless I don't know how to enter the command 7 control-p, it doesn't work. I think the problem is that the manuals referred to the original IIc, with the original ROM. That one you could start from an external drive by typing PR#7, but any IIc thereafter (and Apple upgraded many ROMs for free) could NOT do that. Mine is revision 3 of the motherboard and ROM and so there is no external drive startup.

Being 3 is a good thing because it means it can take memory expansion, but a downside is that they stopped the external drive startup-- pretty silly if you ask me!

In any event, I appreciate your taking the time and chiming in!

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Re: Apple iic, IIc+ boot from external drive; also Unidisk ...

It is possible to boot from an external drive also on later ROM revisions. You just have to type the routine called by PR#7 in the original ROM. This is listed in the technical reference manual.
Go to the Monitor by typing CALL-151
then type
300:FF A9 E0 A0 01 A2 60 4C 0B C6
300G

I tested it on my Rev 0 machine and worked perfectly. Remember that this works with ProDOS disks only.

sm3
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Re: Apple iic, IIc+ boot from external drive; also Unidisk ...

I have a IIc ROM 4. I'm able to boot with the Unidisk 3.5 with no disk in the 5.25 drive, no special key press etc. I guess it's just a matter of the right ROM version.

Also, my IIc+ will do the same thing with its 3.5 drive version (using external drive only).

For those that don't know, drkenb sells the ROM 4 upgrade for $12+ shipping. You supposedly need some basic soldering skill as well.

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Posts: 792
Re: Apple iic, IIc+ boot from external drive; also Unidisk ...

What sort of nonsense! Needing a special ROM just to boot from a second drive?

Needing special commands that only work for ProDOS disks?

What was Apple thinking???

Why could they not invent a special command like "PR#ED1", "PR#ED2" ???

Word Juggler wrote:

Dave, would you happen to know what distinguishes the Unidisk 5.25" from other 5.25"? I found this http://www.vintagemacworld.com/drives.html which suggests that the only real difference is that the Unidisk doesn't work with the Macintosh LC IIe emulation card!

Quote:

There are MANY differences.

Here are some:

The model number for the Unidisk 5.25 is A9M0104, as opposed to the other one which is A9M0107.

Cosmetically, there are two striking differences - the rubber feet at the bottom of an A9M0104 drive are black, while the other drive has tan colored feet. The A9M0104 is tan colored on the outside as well like the original Apple iie, and the ii+, while the other drive has that "platinum" color. The other cosmetic difference is that the A9M0107 has an extra piece of plastic in the back to attach to something.

The analog cards inside the A9M0104 appear to be of older construction.

I suspect that electronically, there are the most significant differences. The mechanical mechanisms for all of these drives including the duodisk are probably compatible. They are robust. According to my experience, if you have a problem with a 5.25 disk drive, then it's probably the analog card or the head needs to be cleaned and the drive speed adjusted.

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Re: Apple iic, IIc+ boot from external drive; also Unidisk ...

The Unidisk 3.5" Drive will boot without any additional command with any ROM Version newer than Version 255. The suggested monitor command is only required for the external non Unidisk 5.25" drive.
Originally with ROM 255, PR#7 would have done the trick. Apple removed this feature to make place for a never released AppleTalk interface. After the interface was cancelled the original code was never restored.