Re: Replacement drive mechanism for 1581

On Sun, 29 Mar 2015, William Levak wrote:

> After lookin through all the specifications on the 1581 and PC connectors, I 
> have concluded that it is not necessary to alter the 1581's system board. 
> All that is necessary is to modify the cable connecting the drive mechanism 
> to the system board.
>
>                PC     1581
> disk change     34      2
> density select   2     not available, connect to signal ground
>                       (any odd numbered line except 1)
>
> Line 3 is not connected on the PC, but it might be on a drive mechanism, so 
> it is best to avoid that line.
>
> Lines that are connected to +5V have a pull up resistor; lines that are 
> connected to ground do not, so I do not need a resistor on "density select".
>
> In addition, the PC interface has lines for a second drive which are not 
> connected to anything on the 1581, but the corresponding signal grounds are 
> connected to ground (13, 17). The PC does not use lines 4 or 6, but their 
> grounds are connected (5, 7).
>
> Line 5 looks like the best choice for grounding "density select".

I have tried several variations on this and it does not work.

Maybe someone out there can see what I am doing wrong.

This is what I have tried:

     PC floppy      1581 board
       line 2        ground       puts density select in DD
       line 34       line 2       connects PC disk change to 1581 disk change
                     line 34      Ready line

I have tried several ways of connecting 1581 line 34 to ground, but the 
drive says "drive not ready"

Any suggestions?


wlevak@sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org

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