CPC 464 3.5" B: Drive as A:

[actualreality]

Hi all
I was recently given a CPC 464 with DDI interface and 3" floppy drive but no software (no CPM disks or anything like that)
I have managed to get a 3.5" floppy drive working as drive B: and of course using SAMDISK, i have copied a few .DSK images of games to 3.5" floppy, and after the |B command i can CAT no issues. 
Of course then after the header program has loaded it looks to A: to load the rest of the program and crashes.
I got the PC 3.5" drive working by plugging in to the B: socket on the DDI, and just had to solder pins 33-34 together to get the drive to work (Sony MPF 920)
I have a Spectrum +3 which i also have a 3.5" floppy working with it, but with that, i have a cable which has a couple of DIP switches on it to force B to work as A and another to switch sides.
Was wondering if anyone had the same issue and got round it somehow.
Look forward tp any help you guys can give me!
Regards
Darren

[IanS]

The mod described in this thread is probably the easiest way to swap drive A & B. ABBA switch, the other way

(It refers to the 6128, but the DDI-1 circuit is the same in the external interface)

[gerald]

The other way does not work  for DDI1 (post edited)
The 6128 free gate is used in DDI1 for making the FDC data separator 8MHz clock.
The good new is that may explain why that gate input are floating on 6128 : they just forgot it !

The only way is to do the traditional ABBA switch, either on the cable or cutting tracks on PCB and add the switch.
My preferend way is cutting track on PCB since replacing the cable may not be trivial in case of error.

Gerald

[IanS]

Ah, I hadn't noticed that on the DDI-1. I'd still be tempted to add my own XOR chip to make the switch a simple two wire effort. With the extra gates, you could also make the default state with no switch connected the nomal unswapped state.

[gerald]

Ah, I hadn't noticed that on the DDI-1.

If actualreality did not asked for a solution, I would not have checked the DDI1 version.

I'd still be tempted to add my own XOR chip to make the switch a simple two wire effort. With the extra gates, you could also make the default state with no switch connected the nomal unswapped state.

You could have the unswapped state with no switch by connecting the 10k resistor to gnd instead of 5v, and use the 5v instead of gnd on the switch.

[Bryce]

I assume the 3.5in disk has been taken straight from a PC and the DS1 bridge is still in place, making it B? If so, you just need to move this bridge to DS0 and it will act as A: but I think you will have to disconnect the 3in drive while using it this way, otherwise both floppies would be replying to A:.

Bryce.

[actualreality]

Thanks everyone for all of your help.
All sorted in the end, got it working by soldering pins 33 and 34 together on the 3.5" and added a switch to the drive itself on pins 11 and 12.  Saves faffing around with soldering in the DDI-1 or knocking chunks out of the cable, works an absolute treat 
Regards
Darren