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Drive numbers outside the 8-11 range via HW?

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#1 Pheonix OFFLINE  


    Chopper Commander

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Posted Wed Apr 17, 2019 10:44 PM

After seeing a drive for sale that had switches to set the drive number as high as 15, I started looking into it.  But I cannot seem to get the details I need.  The HW "jumpers" inside a 1541 or 1571 drive just open or short pins on a VIA chip to ground to set the drive number via HW.  The pins (on the 1571 I'm currently looking at,) are 15 & 16 which are PB5 & PB6 (peripheral B port bits 5 & 6 of 0-7 **correction, 7 not 8**.)  These allow setting device numbers 8-11 (8 if both shorted to ground, 9 if PB5 is opened, 10 if PB6, & 11 if both.)  The drive (a 1581 clone I came across,) allows up to 15, it would seem logical that PB7 would also have an effect, but I'm not really wanting to experiment with real HW without better information.


Does anyone know exactly how drives (any/all really, but mainly working with 1571 & 1541 drives right now,) set the power on device number with the PB pins on this VIA 6522 chip?


Thank you :)

Edited by Pheonix, Wed Apr 17, 2019 10:46 PM.

#2 brain OFFLINE  



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Posted Wed Apr 17, 2019 11:37 PM

$eb3d in the 1541 ROM sets the drive address based on PB5/6, but it masks off additional bits.  If someone had a mapping for devices > 11, it must be a custom ROM or a clone drive.


But, a device can be anything from 8-30, as I recall.  You set set the device number via SW using a program on the test/demo disk.



#3 Pheonix OFFLINE  


    Chopper Commander

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  • 200 posts

Posted Fri Apr 19, 2019 5:57 AM

I saw the option on a 1581 clone (the Firedrive 2/4K ?? or something like that IIRC,) and on a hard drive unit.  So, custom ROM routines, probably.  Was just wondering if the same thing could be done with a 1571 or 1541.  Guess not :(  Oh well, back to my "original" plan.


I keep looking for someone to design & release a sandwich board to fit between a drives board and the VIA chip with jumpers to allow mounting switches (or just using regular jumpers,) to set the drive # via HW without cutting traces or soldering onto the board itself (though installing a socket would probably still be needed in some, if not all, cases.)  Seems the design would be extremely simple.  Same thing could be done with the ???? chip (don't remember off hand, but I have a text file with instructions around here somewhere,) to disable the internal drive of the 128D(CR).  Then all I'd need is some way to reset just the drive portion.  From the little I've read, so far, on it, the drive is a little too integrated into the 128D's design to do that easily, though.  I'm still reading up on that, so I may discover there is a way after all.  Would love to find a switch that does a full throw, but also has an intermittent connection that triggers whenever you flip the switch.  Don't think there is such a creature, though.


Right now, I'm looking into installing a 5v USB A port to plug my upscaler in to, so that it only powers on when I turn on my 128D.  Don't really see a need to have it turned on all the time.

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