Re: 6510 banking question

From: Spiro Trikaliotis (trik-news_at_gmx.de)
Date: 2001-05-07 08:35:28

Since this mail bounced, I repost it...

> > Hi,
> >
> > "Professor Dredd" <profdredd@yahoo.com> wrote on Friday, May 04, 2001
11:26
> > PM:
> >
> > > R6510 is a 6-bit bi-directional I/O port on the 6510
> > > chip. Bits 0-2 of R6510 control the banking inputs of
> > > the PLA. -RESET forces the port to input mode and
> > > clears the port data to $00 (just like the 6526). Then
> > > the pull-up resistors bring the port to output mode
> > > (referring to all 6 lines)
> >
> > No, the pull-up resistors don't bring the port to output mode; they just
> > insure they have H-level when the port is in input mode. The kernel
itself
> > sets the port to output mode. Ruud explained it correct, but you seem to
> > have misunderstood him.
> >
> > > So, if I'm writing my own KERNAL, I can expect the
> > > following conditions after every -RESET:
> > >
> > > PLA configured to ROML/ROMH/IO
> > > D6510 = all outputs
> >               ^^^^^^^
> > all inputs!
> >
> > > R6510 = $00
> >
> >
> > > Hmm ... there seems to be a conflict here ... :-/
> >
> > I hope I have clarified this!

Greetings,
   Spiro.

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