Re: is ADB standard on all Apple products?

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

In article <7APR199509090949@alpha.sunquest.com>,
Robert J. Dull <rjd@alpha.sunquest.com> wrote:
> I recently bought a 14.4 modem from Macwarehouse for my GS.
> The modem connects to an ADB port for power and has another
> connector for the serial port.  When I turn the GS on, the
> modem powers up ok but the mouse freaks out.  Clicking on
> volumes causes them to be renamed to all lower case "a"'s and
> lots of weird flashing on the screen.

Sounds neat!

> I always thought that the GS's ADB was identical to the Mac's,
> apparently that is not the case.  Anybody know for sure?

In hardware terms, they are compatible (except the IIgs doesn't
support the fourth wire, which is used on the Mac II to power up the
computer).

On the software side, the IIgs only has built-in support for the
keyboard and mouse.  Some third-party devices such as some trackballs
(a trackball is a mouse from the computer's point of view) will work
without any special software.

Other ADB devices will only be useful if a IIgs driver is written for
them, and there is software that can make use of the driver.  This
includes some keyboards (e.g. Apple's split ergonomic keyboard),
trackballs, touch windows, modems, etc.

I'm surprised that the modem is interfering in that manner.  It sounds
like it is responding to the same address as the mouse or keyboard.
It shouldn't be defaulting to the same address.

Another possibility is that the modem doesn't follow the standard ADB
protocol, and is interfering with messages to/from the keyboard and/or
mouse.  It might be possible to do this on a Mac, but isn't on a IIgs,
because there is a dedicated microcontroller interfacing to the bus.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand