Date   : Thu, 03 Apr 2008 22:19:03 +0100
From   : beeb@... (Kris Adcock)
Subject: Wires cut in floppy ribbon cable?

Hi Jules - thanks for your reply!

Jules Richardson wrote:

> Grinding noises - hardware failure aside - might just be that you're trying to 
> step the heads on the 'new' drive at a faster rate than it can handle. I 
> *think* that the step rate is done via the keyboard links on the humble BBC, 
> but I could be wrong there.

It's been the same drive all along - all I've done is changed the cable. 
So yes, as you suggest, I think the Beeb is sending signals to ask the 
drive to move the head to somewhere it can't, or at a speed it can't. 
The wires were cut at a point which is most definitely inside the drive 
casing - so it looks like it was done during assembly, presumably to 
defeat an incompatibility with the drive and Beebs.

> 
> I can't remember off the top of my head how the BBC's expected cylinders, 
> spindle speeds, head type and interface data rate compare to 5.25" drives in 
> the PC world; I'm not sure that the two are particularly compatible (at least 
> without changing drive jumpers) - plugging in something that's been pulled 
> from a PC might not work. I *think* BBC drives are always 360rpm aren't they - 
> whereas PC drives are 300RPM for DD and 360RPM for HD...

I suspect there will be some rolled-eyes and tired sighs from some 
people on this list with more comprehensive knowledge, when I say that 
for me, interfacing drives with Beebs (especially when using new drives, 
or mixing 5.25 with 3.5, or picking the right DFS) seems a bit of a 
black art. There's probably all the information in the archives, but I 
have never managed to find a single, friendly, comprehensive resource, 
with photos'n'stuff for mortals like me who need a bit of hand-holding. 
I realise that the fault is with me, rather than anyone else ... :)

Of course, the best way for me to learn would be to start compiling a 
suitable Wiki page, and then let others correct me as I get it wrong ...

Cheers,

Kris.