Re: IIgs questions...

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

Labelas Enoreth <labelas@hotmail.com> wrote:

> In article <1dpm3m7.ohe0l2r2ofa2N@dempson.actrix.gen.nz>,
> dempson@actrix.gen.nz (David Empson) wrote:
> 
> > If software is written expecting the CPU to be running at 1.023 MHz, and
> > it is actually running at 2.8 MHz, then the joystick reading will be
> > something like 2.6 times higher than expected, and the computer will
> > think the joystick is further to the right and down than it actually is.
>
> I thought though, that if a game was 'specially written; for the GS, it
> would work with it fine in standard mode...

As long as the game doesn't assume the machine is going to be running at
Normal speed.

There is one benefit to polling the joystick in Fast mode: better
resolution for determining the position.  The problem is that the
machine speed is irregular when running in Fast mode (due to
interference with RAM refresh), and an accelerated system would throw
everything out.

A game is most likely to use the joystick as a direction indicator, so I
doubt it would gain anything from deliberately reading the joystick in
Fast mode.

> > Some programs let you calibrate the joystick, which may allow them to
> > cope with an "unusual" CPU speed (as long as the counter doesn't run out
> > of bits on a fast enough CPU).
>
> Well, the calibration isn't much, just 'center your joystick and press fire'

That might help, as it would indicate the midpoint; this would be fine
for simple directional movement.  Better accuracy could be achieved by
reading two diagonally opposite positions.

> Also, I don't know hoe much this matters but the joystick actually says
> IIe/IIc/IIgs on the bottom, not IIe/IIc like I first said...

The IIe and IIgs joystick hardware is functionally identical.  The IIc
is slightly different, but close enough that nearly every joystick will
work (and any problems are likely to affect the buttons only).


I'm pretty much out of ideas as far as explaining the up/right movement,
short of a bug.

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