Date   : Thu, 19 Nov 2009 01:23:47 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: BBC INKEY Codes on PCs

Steve Fewell wrote:
> On a BBC Master (Probably BBC B too), pressing The following keys
> simultaneously: CTRL (INKEY -2), F1 (INKEY -114) and F6 (INKEY -118)
together
> triggers the internal INKEY key code -6.
> 
> This does not work in Beebem - probably because the way the PC/Laptop
accepts
> key presses and passes these to applications. I'm guessing that it would be
> impossible for this to ever work in Beebem due to the way Windows handles
key
> presses. Am I correct?
 
Correct. It's a function of the physical electrical wiring of the
keyboard. When you press three keys at the corners of a matrix,
electricity flows such that it looks like the forth corner key is
also pressed.
 
While an emulator /could/ emulate a -6 keypress if -2, -114 and
-118 are all pressed, but the physical PC keyboard has those three
kays at the corner of it's own matix, then a the forth corner on
the PC's keyboard will be virtually pressed, resulting in the
emulator seeing /five/ keys. That fifth key may be at the third
corner of yet another emulated BBC keyboard matrix, so causing the
emulator to generate another virtual keypress.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for the Sinclair Spectrum - http://mdfs.net/Software/Spectrum