Date   : Tue, 19 Feb 2008 22:36:04 +1100
From   : msmcdoug@... (Mark McDougall)
Subject: BASIC error message - "Mis..."?

Jonathan Graham Harston wrote:

> BASIC never checks any I/O locations. No language ever checks any
> I/O locations. It's the Operating System that deals with I/O
> locations. Any access to I/O locations is done by asking the MOS
> to do something.
>  
> Stop thinking about BASIC interacting with the hardware. It never
> does. BASIC will function fully and correctly as long as the calls
> to the entry points at &FFxx do their function.

I understand that!!! What I meant was that inducing a "Mistake" in BASIC may
call a MOS ROM routine that does some I/O that is not done during the
boot-up sequence. I very much doubt that the boot-up sequence accesses and
checks _every_ bit of _every_ I/O location on the machine, so chances are my
implementation is lacking in areas that are only exposed when certain
behaviours are induced, eg 'Mistake', regardless of the fact that the BASIC
ROM is calling MOS routines to access hardware.

Trust me, I'm *intimately* familiar with the concepts of OS entry points,
hardware abstraction layers and platform-independent code...

Regards,


-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"