Re: "Less than" key and PET tape drive, again

From: Ethan Dicks <*ethan.dicks_at_gmail.com*> Date: Wed, 8 Jan 2025 17:58:55 -0500 Message-ID: <CAALmim=1ns=vorjctxdaXh0bPbHn+e46akqUMwqJT3PPAL=R0w_at_mail.gmail.com> · ethan.dicks_at_gmail.com

On Wed, Jan 8, 2025 at 6:30 AM Rhialto <rhialto_at_falu.nl> wrote:
> Thank you so much for finding this! Now I know I wasn't dreaming!

You are quite welcome.

When all I had was a C2N, I used to use this trick on our 2001N/3032
to confirm I was at the end of a tape.  It was that or take the tape
down to my step-dad's Hi-Fi and make it screech (which he did not
like).

> It even works in VICE, since it turns out that isn't some weird hardware
> bug.

The bug, I think, is that in some cases, the high-bit of PIA1L is left
in the wrong state which then causes this code to incorrectly suppress
the "<".   The "fix" in the footnote in "Programming the PET/CBM"
restores the value of that bit to the default which "repairs" the <
key.  I don't ever remember < "breaking" on my machine but it's
mentioned by two authorities so I'm sure it must have happened.

> $ xpet -default -model 3032 -1 "some-random-tap-file.tap"
>
> Virtually press "Play" using the pop-up menu on "Tape #1: 000".
> Then press the < key.

Neat!

-ethan