Re: How much of a ][ is needed to twitch?

["Alex Freed" <alexf@mirrow.com>]

"Tristan Mumford" <xtristan.xmumford@xgmail.xcom> wrote in message 
news:45d1994e$0$52907$c30e37c6@lon-reader.news.telstra.net...

> I'm fairly sure the logic of the controller is compatible with the floppy
> drive and shouldn't need anything like pullups. Can someone (dis)agree 
> with
> me on this please?

I did something similar to your project some 20 years ago - interfaced a
generic "industry standard" disk drive to A2.
The main things to do:

1. Convert motor phases to "step" and "direction".
I used a couple of chips to do it, but it *MAY* be possible to directly
use one ODD phase as "direction" and OR EVEN phases for step.
I didn't do it this way, but it looks like RWTS always have one odd
phase active when an even phase gets active.

This will NOT provide half-tracks.

2. STEP should be disabled when TRACK0 is active from the drive.

3. Write data line will need a one-shot circuit.

I could have forgotten other issues.
And the last point is: don't even start doing anything till you buy/make
a logic probe.

-Alex.