Re: Extension Problem Solved!

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

In article <4954vd$e6s@gap.cco.caltech.edu>,
Nathan Mates <nathan@cco.caltech.edu> wrote:
> 
>    [Easy Access]
>
> Heck yes. That thing causes so many problems with other programs
> (theoretically, it's the other programs that aren't quite written 
> correctly, but there are so many of them, and only EasyAccess is the
> problem) that I think it should not be installed by default. It's
> installed to give some people with 'disabilities' more access to GS
> functions, but since I have none that are computer-related, EasyAccess
> gets toasted real fast.

I am not disabled, but I have found Easy Access to be very useful on
occasion.  If I have a cup of tea in one hand, "sticky keys" makes
typing multi-key sequences a lot easier. :-)

Seriously, though, the "keyboard mouse" facility is a godsend if you
are trying to position the mouse cursor precisely.

Note that Easy Access is built into the keyboard microcontroller on
the ROM 3 IIgs, and it has no software compatibility problems.  The
"EasyAccess" INIT, if installed in a ROM 3, doesn't do anything except
display an icon in the menu bar to indicate the state of Sticky Keys.

In a ROM 1, the "EasyAccess" INIT actually implements the Easy Access
facilities, which can cause software compatibility problems:
keypresses are intercepted at a very low level by the INIT, using
interrupts, and are then pre-processed before being fed back into the
keyboard microcontroller.  They subsequently appear at $C000/$C025, as
normal.

The main compatibility problem is with programs that try to wait for a
keypress while interrupts are locked out.

With EasyAccess installed on a ROM 1, the program will never get a
keypress, as interrupts are required for the computer to receive them.
The program will wait forever.  You cannot even use
Control-Apple-Reset to get out of this situation, because it is a
keypress like any other, that has to be handled by EasyAccess before
it will actually cause a reset!  The only solution is to turn the
computer off. 

As I indicated above, none of this applies to a ROM 3, whether or not
you have the EasyAccess INIT installed.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand