Re: Goodbye AppleDesktopBus

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

Cturley2 <cturley2@aol.com> wrote:

> Hi Brian,
> The way I see things with ADB devices and use - no need to comment on
> Goodbye to ADB - it ain't going nowhere.  We have the ADB machine for the
> ADB devices to work with - forever.  If somebody makes a new device in the
> ADB manner - same goes, all will be able to have, buy and use it.  Even
> the OTHER new method of the iMac connectivity devices (i.e.)  up to 127
> such devices connected at the same time can be implimented for use with
> the A2 machines with a simple (currently existing conversion/connector)
> sold commercially for a fairly reeaonable price. I just got a catalog in
> the mail yesterday offering such a conversion connector.

Are you sure about that?  There have been many USB interfacing devices
mentioned in recent months, but all the ones I'm aware of allow other
devices to be connected to a USB bus, _not_ USB devices to be connected
to another bus (such as ADB).

I suspect what you saw was a device that allows an iMac (for example) to
use an existing ADB keyboard or mouse, i.e. ADB slave devices working on
a computer that supports USB.  There is no way that this would work the
other way around (USB slave devices on a computer that supports ADB).

Apart from anything else, ADB is several orders of magnitude slower than
USB: ADB maxes out at 10 kilobits per second, while USB is either 1.5 or
12 megabits per second.

Another thread mentions a USB/LocalTalk interface, and the same
principle applies - LocalTalk would be far too slow to support a USB
peripheral.  (I have yet to see any "official" mention of such an
interface existing.  Macintouch refers to Ethernet-to-LocalTalk
interfaces, which are well established.  I doubt think there is a market
for a USB to LocalTalk interface, and it wouldn't fit well with the
design of USB anyway.)

In any case, there are still protocol issues.  I don't know anything
about the USB communications protocol, so I have no idea how complex it
would be to implement a protocol translator for some other interface on
the host device.


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