Date   : Tue, 18 May 1993 17:02:59 +1200
From   : David Andrew Sainty <David.Sainty@...>
Subject: BBC Caps lock thru S/W

smcgnnss@... says:

   Name: Read/write keyboard status byte

   call address: &FFF4 
   A=&CA (202)

   For the Beeb:

   bit 3 -1 if shift is pressed
   bit 4 -0 if caps lock is engaged
   bit 5 -0 if shift lock is engaged
   bit 6 -1 if ctrl is pressed
   bit 7 -1 shift enabled, if a lock key is engaged then shift reverses the lock

   The old status byte is returned in X
   <new value>=(<old value> AND Y)EOR X

I have a feeling that this does not actually alter the led display until
a keyboard interrupt is fielded. *fx118 will update the led's.

Alternatively you could directly access the 8 bit addressable latch driven
off the system VIA, but this is messy (and can't be done safely from BASIC).


   While I am here - a question about the Master ROM sockets

   There is one free sideways ROM socket an the master and I have ViewStore
in it at the moment
   Can I page out one of the sideways RAM banks and put this EPROM (VIEWSTORE)
in the free 
   socket ???

   Does it matter that the EPROM is 16K (I think) and the socket is 32K wide??

Unfortunately, doing this will cost you two ram banks, not just one. The
16k and 32k chips have a physically identical interface (apart from one extra
line on the 32k device that is unused on the 16k device). So the 16k chip
will behave just fine under the 32k interface. You'll probably get two copies
of Viewstore appearing though instead of one.