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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: AmigaMuze on April 19, 2006, 10:40:00 AM

Title: Pin numbering for U8 - 8528 on A500
Post by: AmigaMuze on April 19, 2006, 10:40:00 AM

I have an A500 that df0: quit working on.  I found a mod (bootfromdf1 (http://www.textfiles.com/computers/bootfromdf1.txt)) to cross the drive selects on the board to cause the external df1: to be bootable from.  I am trying to determine which pins of U8 - 8528 are 13_SEL0 and 14_SEL1.  I'll take a picture and post it here if anyone wants to look at the board.

Title: Re: Pin numbering for U8 - 8520 on A500
Post by: AmigaMuze on April 21, 2006, 05:59:45 AM

I typed the wrong number in my last post.

U8 - 8528 should have been: U8 - 8520.

Here is a link with a picture of the board.
A500 board (http://www.amiga-hardware.com/download_photos/a500mb_rev5_2.jpg).

If anyone could tell me which pins are 13 and 14 of U8 8520A-1 it would be real helpful.

Thanks

Title: Re: Pin numbering for U8 - 8520 on A500
Post by: zipper on April 21, 2006, 09:37:59 AM

See that notch on the chip (right) and big 1 on the PCB? The notch is on the end which has pin 1 and pin 1 is mostly printed on A500 mobos. And numbers run ccw.

Title: Re: Pin numbering for U8 - 8520 on A500
Post by: AmigaMuze on April 22, 2006, 11:22:55 AM

Thanks for your comments zipper.

I completed the mod and triple checked things.  df0 bumps regardless of which position the switch is in when booting.  df1 lights up continously but does not bump when booting with the switch in one position.  When booting in the other position df1 doesn't do anything.  Changing the position of the switch after booting seems to make no difference in df1.  I wonder where I could've gone wrong.