It’s been a long time since I did this mod, but I had to put a resistor on the disk change line. I don’t know if any particular value is needed and I don’t have a 1581 to test on anymore. I just grabbed something out of my parts box. > On Apr 17, 2015, at 4:32 PM, William Levak <wlevak@SDF.ORG> wrote: > > 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? > > > firstname.lastname@example.org > SDF Public Access UNIX System - http://sdf.lonestar.org > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing list
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