Re: GS Weakness is the keyboard????

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

SirThomas <sirthomas@aol.com> wrote:

> Speaking of "upgraded" GS keyboards, has anyone gotten the Apple Adjustable
> Keyboard to work with the GS?

I haven't heard of anyone achieving this.

The reason it doesn't work is that it almost certainly uses a "device
handler" code number that is not supported by the IIgs keyboard
microcontroller.

Each ADB device has an 8-bit device handler code that specifies how the
device is to behave.  It can be set to different values under software
control to adjust major behavioural options.  For example, the Apple
Extended Keyboard has two different handler codes: the normal one, and a
special one which enables independent detection of the left and right
modifier keys.

Most keyboards support the device handler code of the Apple Standard or
Extended keyboard as a fallback option, but the adjustable keyboard
probably does not.  It may also have other architectural differences
such as the organisation of the registers which hold the modifier key
states.

The only way this keyboard could work on the IIgs would be if someone
wrote a special driver for it.  This driver would disable normal
keyboard support and poll the adjustable keyboard directly, feeding
keypresses back into the ADB microcontroller as they are detected.

This is exactly how the Easy Access INIT works on a ROM 01 IIgs, and it
causes a lot of compatibility problems, e.g. software that waits for a
keypress with interrupts locked out will cause the computer to hang.

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