Re: Appl //c Basic

[dempson@actrix.gen.nz (David Empson)]

Paul Schlyter <pausch@saaf.se> wrote:

> In article <3b3f1f24$1@news.iprimus.com.au>,
> Mark Cummings <NOTfigjams@primus.com.au> wrote:
>  
> >> You can't make the reset do nothing - it has to jump somewhere.
> > 
> > jump - fair enough, do nothing - depends on your definition. a BRA #$FE
> > would do virtually nothing, at least not as far as the user is concerned.
>  
> It would hang the computer, and that would, to the user, be a quite
> noticeable action!

I agree.  I was interpreting "do nothing" as meaning "resume as if the
user didn't press Control-Reset", rather than "freeze".

> Also: the BRA opcode was undefined in the early versions of the 6502

It wasn't defined in any version of the 6502.  BRA is one of the new
opcodes defined by the 65C02.

> and will this not work on Apple II's earlier than the IIe.

It will not work on an unenhanced IIe either.

> To get it to work on earlier Apple II's as well, do something like:
>  
>     CLC
>     BCC #$FE

And of course, few if any assemblers will accept this as valid source
code.  :-)