Date   : Sat, 18 Nov 2006 01:15:38 +0000
From   : splodge@... (Richard Gellman)
Subject: Unusual piece of equipment available.

Jonathan Graham Harston wrote:
>> Message-ID: <45492360.7020500@...>
>>     
>  
> Richard Gellman <splodge@...> wrote:
>   
>> What we have on offer here is a floppy disc drive cable (of the BBC
>> Micro variety) with one edge connector on the end, but fitted with a
>> switch to convert an 80-track drive into a 40/80 switchable.
>>     
>  
> How? There are no connections on the disk drive connector to
> control the number of tracks or the stepping rate. Some disk
> drives have links or pads on them that a switch can be wired to,
> but that is on the PCB, not on the drive connector.
>   
I can't be certain on this (given recent discussions on step rate, etc), 
but the cable is routed via a small circuit board with a couple of ICs 
on it before it gets to the drive.

My guess is its issuing a second step signal on receipt of the first, 
thus making an 80 track drive double step, effectively becoming a 40 
track drive. I imagine the switch simply bypasses this add-on board for 
80-track mode.

The switch itself was somewhat crudely fitted to the rear of the metal 
case, the drive itself have no track switching on it whatsoever. The 
"upgrade" also require two wires soldering the power connector for it to 
work.

I've had one email of enquiry on this, but they've since not got back to 
me. If I don't hear from them in the next couple of days, the cable is 
yours.
>  
>   
>> The cable is available to any interested party, free of charge, and I
>> won't even ask for postage costs :)
>>     
>  
> I'll add it to my collection of "odd stuff", aka take a photo and
> put it in the basement :)
>   
I can provide a photo (JPEG) of it if you want a better idea of how it 
does what it apparently does.

-- Richard
>  
>