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Apple IIe DuoDisk only uses drive 1

iie duodisk

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#1 d_a_parker OFFLINE  

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Posted Sun Jan 27, 2019 10:53 PM

Hello!

I recently acquired an Apple IIe with a DuoDisk. The computer seems to work fine, but something weird is going on with the disk drives. It reads from and writes to Drive 1, even when Drive 2 is specified.

For example, both CATALOG,D1 and CATALOG,D2 both read the disk in Drive 1 and list its contents.

With the DOS 3.3 system disk in Drive 1, I tried running COPYA. I put a blank disk in Drive 2, specified Drive 1 as the source and Drive 2 as the destination. The reading step went fine, but then it tried to format the destination disk and failed because the system disk in Drive 1 is write-protected.

I have verified that the I/O card for the DuoDisk is in slot 6 and all of the connections seem fine.

Any advice or ideas are greatly appreciated. Thanks!

#2 BassGuitari OFFLINE  

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Posted Thu Jan 31, 2019 12:40 PM

To piggyback on this, I run into this same problem when I try to boot DOS from CP/M (Softcard //e) in DuoDisk Drive 2.  "BOOT D2," or whatever the command is, would only boot from Drive 1.

 

Once in DOS, I'm golden--I can do anything I want with Drive 2. But CP/M is giving me static for some reason.



#3 d_a_parker OFFLINE  

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Posted Tue Feb 5, 2019 10:46 AM

Just a quick update: I tried copying a disk using both Copy II Plus and ADTPro.  The issue persists.  These programs say they are reading/writing Drive 2, but actually use Drive 1.

 

If anyone has any advice on next steps for troubleshooting, it will be appreciated.  Thanks!



#4 Aunty Entity OFFLINE  

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Posted Tue Feb 5, 2019 5:48 PM

Sounds like a device select line isn't pulling its weight.  If its not throwing any other errors... I don't have any hard and fast idea where to start though, it'd have to originate on the controller and run all the way through to the interface inside the duo.  Might require some schematic looking.

 

A



#5 Aunty Entity OFFLINE  

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Posted Wed Feb 6, 2019 1:14 AM

There's supposedly a tech note that covers this.  Apparently it was a "thing"...

Haven't found it though



#6 Aunty Entity OFFLINE  

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Posted Sun Feb 10, 2019 6:15 AM

Never did find the tech note, but check there's no shorts in the cable from card to drive. That might pull drive select permanently up or down depending whats happening.



#7 d_a_parker OFFLINE  

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Posted Tue Feb 12, 2019 9:13 PM

Thanks for the info.  I found the 590-0114 cable pinout online, and tested the voltages on the ENBL A and ENBL B lines (DB-25 pins 11 and 8, respectively).  I assume ENBL A is Drive 1 and ENBL B is Drive 2.  Anyway, I got very consistent results:

 

At Rest (baseline state):

ENBL A = 4.44 volts

ENBL B = 0.24 volts

 

Reading Drive 1:

ENBL A = 0.09 volts

ENBL B = 0.89 volts

 

Reading Drive 2:

ENBL A = 0.09 volts

ENBL B = 0.87 volts

 

I tried reading from each drive using both CATALOG and Copy II Plus.  It seems that the voltage drops significantly on A and nudges upward on B in either case.  There doesn't seem to be any dramatic difference calling one drive or the other.  Is it possible the controller card is messed up?  Or maybe the cable?

 

If anyone happens to know the expected results for those lines when reading from each drive, that would be  very helpful.

 

Thanks!

Dave



#8 Aunty Entity OFFLINE  

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Posted Tue Feb 12, 2019 9:37 PM

If the state of the two lines is the same reading either drive, that could be your smoking gun right there... I'm sorry I don't have the tech details to help a lot more. You could try checking the signal states on the card itself without the drive attached.  It might help rule the card out.  I'll see if I can find something more useful



#9 d_a_parker OFFLINE  

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Posted Wed Feb 13, 2019 12:12 PM

Thanks, I will test directly from the DB-19 on the controller card when I have time and post my results.  I was testing the pins on the DB-25 end while it was disconnected from the DuoDisk, so in theory those should be the values coming from the card, unless something is seriously wrong inside the cable.
 
I was poking around for more information and I found the AppleService Technical Procedures document for the DuoDisk:
 
 
It provides fixes for several problems but not this one.  However, it refers to the Apple 5.25-Inch Disk Drive Diagnostic diskette, which I can't find much information about but seems like it might be handy.  Does anyone happen to know if there's an image of this disk available for download?
 
Thanks!
Dave


#10 Aunty Entity OFFLINE  

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Posted Wed Feb 13, 2019 5:42 PM

It provides fixes for several problems but not this one.  However, it refers to the Apple 5.25-Inch Disk Drive Diagnostic diskette, which I can't find much information about but seems like it might be handy.  Does anyone happen to know if there's an image of this disk available for download?

 

Not off hand, that'd be another whole search :)  I have a duodisk "guide" in the winds, I'm just awaiting access too, once I have it I'll post.  Most of the documents I've seen thus far mostly refer just to the drive mechanisms.  Like the one you have there.



#11 Aunty Entity OFFLINE  

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Posted Wed Feb 13, 2019 7:50 PM

https://mirrors.appl... 800k image.2mgweirdly enough its an 800k 3.5" disk image itself... not sure how that works out.  The guide I was waiting for turned out to be another copy of the same service guide already seen.



#12 d_a_parker OFFLINE  

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Posted Fri Feb 15, 2019 11:17 AM

It turns out that one of my colleagues has an identical IIe with a DuoDisk, and both drives work fine.  We're going to test the line voltages on that one, and then I'll have something to compare my results to.  Hopefully this will at least narrow it down.

 

Things are looking less hopeless!


Edited by d_a_parker, Fri Feb 15, 2019 11:18 AM.


#13 Airshack OFFLINE  

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Posted Today, 10:41 AM

Assuming you're using the DuoDisk controller card and not the standard disk controller card? I saw one of these on shop goodwill.com and wondered if the standard disk controller card would be a problem?





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