Conference 7.286::atarist

    	There is a lot of software that can't be booted from drive B,as
    after the initial boot,the software attempts to access
    drive A directly for additional files.
        
    	A good work around is to make your double sided external drive
    as drive A.
    
    	The drive select lines come from the yamaha sound chip,you need
    to cut the appropriate pins for select A and select B and cross over
    the signal.(perhaps via a switch so you can change back).
    	If you want the details,I'll enter them here.
    
    	This of course doesn't explain why it didn't work with a double
    sided internal drive.Did you try formatting the internal drive to
    720k after you installed it to make sure it worked.
    
    	Brian...

    Brian,
    	  I would appreciate any details you have on drive swapping. Do you
    think if I made a backup copy of the game disk and had that in drive A,
    that is supposing that I can fit most of the files on, would it then
    boot okay? well I suppose the easiest way to find out is to try.
    Any other suggestions would be appreciated,
    
    			thanks in advance Paul!!!!!!!

    DUNNO IF THIS IS GOING TO BE ANY HELP, BUT I WAS IN THE SAME SITUATION
    AS YOU A WHILE BACK, BUT GOT A DISK B-BOOTER FROM A FRIEND.  STILL THE 
    THING THAT HAPPENS IS THAT IT STARTS BOOTING FROM DISK B, AND THEN
    SUDDENLY SWITCHES TO THE INTERNAL DISK A, WHAT I DID WAS SIMPLY KEEP
    TAKING THE DISK OUT OF DISK B AND PUTING IT IN A WHEN NEEDED, AND VICE
    VERSA, WORKS FOR ME...NO HARM IN TRYING.
    
    BISH.

    Thanks for the tip Bish I'll try that tonight but I don't think it will
    work as the internal drive is only single sided, it won't be able to
    read the double sided disk. Still I'll give it a bash.
    
    	Still waiting to hear from Brian Loxton on the A/B switchover
    option.
    
    			Paul!!!!!!!

    	The drive select lines come from the YM-2149 yamaha sound chip.
    
    Drv 0 select comes from pin 20 and drv 1 from pin 19.(Please check
    these with a meter to pins 5 and 6 on the floppy drive socket).
    
    To change over drive a/b select, isolate the 2 pins from the pcb
    track,solder wires to the chip pins.Then for a permanant change
    connect the wire from pin 19 to the track for pin 20 and the wire
    from pin 20 to the track for pin 19.
    	A better way is to make it switchable.
    
                           I-------TRACK TO PIN 19
    	 2149 PIN 19---aX  X  Xb
    	 2149 PIN 20---bX  X  Xa
                           I_______TRACK TO PIN 20
    			2-pole 2-way switch. (connect a-a and b-b)
    
    The chip is located underneath the internal disk drive. 
    
       ----------------------------------------back of Atari
                I---20
                II--19
    		**----------------------
               I         YM-2419        I
               I			I 
                ------------------------ 
    
    	Hope this is understandable......
    			Brian
                                    

    Thanks Brian,
    		I'll try this as soon as I've fixed the blasted floppy
    problem that has just come up. The internal floppy stopped accessing
    disks over the weekend but is okay when the external drive is not
    physically connected. I'm pretty sure it is the WD1772 floppy
    controller chip as I have tried another external drive and the same
    thing happened. Firstly can anyone tell me of a source of said chip and
    secondly is anyone familiar with all the jumper settings on the drives?
    I would be interested to know what they all do and mean.
    
    
    	The jumpers on the Mitsubishi drive are as follows:-
    
          Obviously DS is drive select but does it matter which of 0-3 is
    selected, and if youve got two drive should they be e.g. 0 & 1.
    
    
    	the others are:-
    
    		MX
    		IV
    		MS
    		MM
    		SR
    		DC
    		1X
    
    			What are they???
    
    thanks Paul!!!!!!!
    		

re: .6

Where are you?

I have a WD1772 I don't need.  I thought I had a problem with said chip,
I got one, but it didn;t fix it.  The chip is brand new.  Original
cost about $20 -- how about $12 plus shipping?

If you are US area and interested, let me know.

Chad

Drive select on BOTH drives must be set to 0.

	Ray

    thanks Chad for the offer but I'm across the pond in the UK so it would
    probably be easier to find somewhere a bit nearer home. Thanks anyway
    for the offer,
    
    		Paul!!!!!!!

    I've got some circuit diagrams for the ST if thats any help.
    
    	(Reply today because i'm away for two weeks.)
    
    
    
    Brian..

    yes please Brian,
    		     I have probably replied too late but I would like them
    any way when you get back thanks,
    					Paul!!!!!!!

    I have sorted out my drive mishap, it was a cable problem. I have also
    done the modification on the drive select to make my external drive,
    drive A, it works fine.
    
    		Thanks very much for all the constructive comments,
    
    
    				Paul!!!!!!!