Re: Weird issue with the Pet 2001-N

From: David Roberts <daver21145_at_gmail.com>
Date: Fri, 5 Apr 2019 16:55:36 +0100
Message-ID: <CAC5emFHLY8L1Mp+Y7b0nGBwM+-Zn-Q1B_1MrjJhoA5qyd7V-cA_at_mail.gmail.com>
I agree, for a large sample.

But the OP has not stated that; only that a simple direct statement caused
an issue.

The OP could try loading a$ with "ABCDEFGHIJKLMNOPQRSTUVWXYZ" and see what
the result is when printed...

Dave

On Fri, 5 Apr 2019 at 08:07, Francesco Messineo <
francesco.messineo_at_gmail.com> wrote:

> On Fri, Apr 5, 2019 at 8:29 AM David Roberts <daver21145_at_gmail.com> wrote:
> >
> > It could also be the octal read buffer from the screen RAM dropping a
> bit rather than the main RAM itself. The 'Y' gets entered onto the screen
> correctly. I can't just remember off hand whether the command line is
> constructed in main RAM or read from the screen RAM when RETURN is entered.
>
> if this would be the fault, then every byte entered on screen would
> suffer the same problem, so it would result in a lot of syntax errors.
> If only the variable names are affected, I would still think about a
> fault in bank 1 DRAM/data bus.
>
> >
> > Just a thought, I will have a look in more detail later on today.
> >
> > Dave
> >
> > On Wed, 3 Apr 2019 at 08:19, Francesco Messineo <
> francesco.messineo_at_gmail.com> wrote:
> >>
> >> On Wed, Apr 3, 2019 at 3:57 AM Steve Gray <sjgray_at_rogers.com> wrote:
> >> >
> >> > Sounds like bit 3 is being dropped when stored as a variable. That
> would suggest that you have a bad ram at the top end of user memory space.
> >>
> >> That could be possible, but the fault must still allow the RAM
> >> initialization and check to function properly, it the correct bytes
> >> free amount is printed at startup.
> >> RAM is initialized with $AA if I remember correctly, so bit 3 = 0
> >> would be possible and not detected.
> >> If it's a 2001N with two banks, the problem is likely on bank1
> >>
> >> Frank
> >> >
> >> > Steve
> >> >
> >> >
> >> > > On Apr 2, 2019, at 9:07 PM, David Laffineuse <
> davidlaffineuse_at_me.com> wrote:
> >> > >
> >> > > The keyboard seems to be working perfectly fine.
> >> > > For instance if I type on the key 'Y', the letter Y is displayed on
> the screen.  However if I set a variable to Y, e.g. a$="Y" then I print a$,
> I get a Q on the screen...
> >> > > The same occurs with I which produces an A, H which produces _at_, Z
> which produces R, X which produces P, 8 that produces 0, and 9 that
> produces 1.  All the other letters are fine.
> >> > > What is going on?
> >> > > David
> >> >
> >> >
> >>
>
>
Received on 2020-05-29 21:17:23

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