Re: Repairing a SFD-1001 (8250/LP, 8050, 4040, 3040, 2040)

From: Jim Brain <>
Date: Thu, 11 Aug 2011 22:18:03 -0500
Message-ID: <>
On 8/11/2011 8:33 AM, Hoffmann-Vetter, Martin wrote:
> Pin 21 from the 2332 must be used to generate the chip select for the 
> eprom. Is that the wire to pin 2 of the 84hct86? If yes, this can be 
> work. Only if the 2332 is programmed with on chip select at pin 21 or 
> non chip select would be a problem. You can't disable the use of the 
> chip select from pin 20, you can only programm the polarity. You need 
> the jumper SJ3 for output enable (pin 22) of the eprom, too. Greetings 
> Martin Message was sent through the cbm-hackers mailing list 
Looking at the 2316, I think I need a different strategy.  I wonder if 
there's a solution that uses a single '138 and some jumpers and pullups.


I was thinking I could feed the CS1,2,3 lines into the '138 with jumpers 
and pullups on the '138 input lines.  Then, 8 jumpers to select which 
combination was needed for the JEDEC /OE line.  That would handle 
inversions of any line, but each of the CS lines needs 3 states:

connected to nothing
connected to '138
connected to JEDEC pinout.

So, I'd need 3 2 way jumpers and 8 1 way jumpers to handle every 


Jim Brain

       Message was sent through the cbm-hackers mailing list
Received on 2011-08-12 04:00:26

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