Re: IIc+ & ProTerm

["Simon D. Williams" <bb065@chebucto.ns.ca>]

On Sat, 10 Jun 2006, David Empson wrote:

> vSimon D. Williams <bb065@chebucto.ns.ca> wrote:
> 
> > On Fri, 9 Jun 2006, Pete PPP wrote:
> > 
> > > Proterm uses keyboard emulation to simulate an extended keyboard.
> > > 
> > > On a //c+ (or even a //c) use the option key with the arrows. Perhaps a
> > > little unwieldy but that is how it is. 
> > 
> > Bless you Pete! It works!!!
> 
> A little speculation as to the background behind this behaviour...
> 
> On 8-bit Apple II machines, the only information available from the
> keyboard is the encoded value of the key you pressed. The arrow keys
> generate control characters (e.g. Ctrl-H for LeftArrow). The
> Command/Option (OpenApple/ClosedApple) keys are detected separately as
> if they were paddle/joystick buttons. In machines with the shift-key mod
> (standard on some models), the shift key can be detected in the same
> manner.
> 
> The Control key cannot be detected, which means that if ProTerm sees an
> $08 in the keyboard buffer, it can't tell whether you pressed Ctrl-H or
> the LeftArrow key.
> 
> The Option/ClosedApple key can be detected separately, so they use this
> to identify when you want to generate a VT-100 arrow key sequence.
> 
> 
> On the IIgs, software has access to more information about the keys
> being pressed.
> 
> At the simplest level, it can tell which modifier keys are being held
> down (Command, Option, Ctrl, Shift and Caps Lock). For example, this
> means that the left arrow key can be distinguished from Ctrl-H, because
> an $08 ended up in the keyboard buffer without the Ctrl key being held
> down. Using this method would, however, confuse Ctrl-LeftArrow with
> Ctrl-H.
> 
> ProTerm can therefore rely on the modifier register to detect that you
> are pressing an arrow key and generate the appropriate VT-100 key
> sequence instead, and still allow you to type Ctrl-H and have it handled
> correctly.
> 
> It is also possible with an ADB keyboard on the IIgs (but not the
> built-in keyboard on a IIe upgraded to a IIgs) to bypass the standard
> keyboard decoding and directly access the keyboard's raw keycodes. In
> this case, every individual key-up and key-down operation can be
> identified, allowing even more accurate identification of which keys are
> being pressed, e.g. left-shift vs right-shift.
> 
> -- 
> David Empson
> dempson@actrix.gen.nz

...if only I'd read the handy ProTerm Quick Reference guide that
was within reach the whole time... ;-(

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