Re: Joystick Devices

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

In article <4u3rdi$9kc@news.innet.com>, saw@camalott.com (Alan) wrote:

>Hi all!
>
>dempson@actrix.gen.nz (David Empson) wrote:
>
>>It would be better to use the Macintosh version of the TouchWindow, which
>>is an ADB peripheral.
>
>I might agree, except for those that want to use it on pre-GS models.

Since I was talking about a GS/OS driver, this is a moot point.

The problem with the Apple II version of the TouchWindow is that it
requires a lot of intensive polling.  To get reasonable results means
disabling interrupts, slowing the machine down to 1 MHz, and sitting in a
loop polling it for up to three milliseconds, preferably twice to get
decent readings for X and Y.  This should be done as often as possible.

As you can see, this tends to affect the performance of the machine
somewhat.  It is likely to kill AppleTalk connections if the TouchWindow
is polled frequently enough.

The same goes for using a joystick as a mouse.


The advantage of the Mac TouchWindow would be that the ADB polling doesn't
require slowing the machine down or locking out interrupts, so it won't
have such a major impact.  (It should also take less time to do a poll.)

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