Date   : Tue, 26 Feb 2008 23:52:33 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: BBC FPGA Boots to BASIC... almost...

Mark McDougall wrote:
> Mark McDougall wrote:
> > If I run the code as I interpreted it (LDA &103 - absolute), I do get
> > something recognisable, but with lots of '*' and error messages are
printed
> > like '*istake'...
 
Double Doh! BASIC often calls WRCH via JMP (WRCHV) instead of
JSR OSWRCH, so patching OSWRCH to JMP to the test code won't work.
You'll have to change the default WRCHV contents, which is the
eighth entry in the table table pointed to by &FFB7. &D94E in OS
1.20.
 
Put the test code at &C000, change (&D94E) to &00 and (&D94F) to
&C0.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
United Kingdom Tercentenary : 1707-2007 : http://yr300.org.uk