Re: Commodore drives can be controlled on Apple II serial!

[dempson@actrix.gen.nz (David Empson)]

Supertimer <supertimer@aol.com> wrote:

> From what you wrote and what Doug wrote, I see that PH0-PH3
> can be used to provide the 4 control lines necessary for driving
> a Commodore disk drive.  From what you wrote above, I see that
> the SmartPort is probably too timing critical to accept the actual
> transfer of data.

Well, only through the actual data pins.  You could still do it by
toggling a digital output and sampling a digital input.

> How about a Y-cable?  On the A2 side, this cable would be a split
> connection, with one plug in the serial port and one in the SmartPort.

The serial port is not electrically compatible with the 1571 drive, if
what I've read in these threads is accurate.  (They use TTL-level
signals, not RS-232.)

> Or can any signal at all in the SmartPort accept data transfer at a
> nonstandard rate?

As long as you use a signal that is controlled directly by the CPU, or
is not mangled noticeably by the logic state sequencer, then you have at
least four digital outputs, and I think you can use the wrprot/sense
input by putting the IWM into the right mode (this may limit the
usability of some other signals, e.g. the enable outputs).

The only questions are how fast these signals need to be toggled or
sampled, and whether there are enough signals to control the drive.  I
can't help with either of these issues, as I know nothing about the
Commodore drives other than what has been posted here recently.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand