::: Area #102 (BBC Echo)
Message: #1297 (Read 1 time, has 0 replies, 1968 bytes)
Date   : Sun May 31 13:38:34 1998
From   : Jonathan Graham Harston of fidonet#2:254/27
To     : All
Subject: Subject: Running a BBC Without A Keyboard

JGH> I added the above code to HADFS, blew an EPROM and plugged it in.
JGH> Switched on the machine without the keyboard... HADFS Startup banner
JGH> appeared, and then sat there again, apparently waiting for Shift to
JGH> be pressed.  On pressing reset, it continues ok.  So, there's just
JGH> the Power-On Reset bit to solve.

Oh, of course.  I've called the NoKeyboardCheck routine /after/ trying to
print the startup banners, so of course it going to hang.

Quick tweek from:
  .Serv1
  JSR StartupDisplay
  JSR CheckNoKeyboard

to:
  .Serv1
  JSR CheckNoKeyboard
  JSR StartupDisplay

and it works.  Shift/Ctrl pausing must be disabled /BEFORE/ any text is
output.

As an aside, the routine I'm suggesting checks if Osbyte255 is zero. If
there is no keyboard, Osbyte255 will be zero, but that does not mean that
if Osbyte255 if zero there is no keyboard.  You could do *FX255,0 and then
press Break which is a handy way of testing the routines, and checking for
it is sufficiently robust for the use it's being used for.  To /actually/
check for the presence of a keyboard you should do something that
effectively does an INKEY on /all/ keys from -1 to -128.  If /all/ return
-1 (ie, pressed), then there is no keyboard.  It's not possible for all
keys to claim to be pressed when there is a keyboard plugged in (unless
you have 70 fingers! 8) ).

In Basic, it would be:

DEFFNKeyboardPresent
  Key%=0
  REPEAT
    Key%=Key-1
  UNTIL (INKEY Key%)=0 OR Key%<-128
=Key%=-128

--
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
BBC+Master / Z80+6502 / CoPro+Tubes / Econet+SJ / Devolution / Transport /
Planning / Highways    http://homepages.nildram.co.uk/~amilton/walkley.htm
jgh@arcade.demon.co.uk   (( Anti-UCE address added by Arcade, not by me ))
--- ARCbbs RISC OS [1.64á32c]
 * Origin: Arcade - The Definitive Acorn BBS +44 181 655 4412 (2:254/27)