Re: Projects that take Commodore computers to 2021

From: Charlie Hitselberger <chitselb_at_gmail.com>
Date: Mon, 13 Dec 2021 18:52:41 -0500
Message-ID: <CAGRnEnW6Ct=+KBUw744awDpEVoVb8sGk8j5cx_rrc1T8n+7hxA_at_mail.gmail.com>
I am putting together PETTILmobile, a rolling computer bus, powered by PET,
to teach Forth (aka PETTIL) amd 6502 and Sweet16


On Mon, Dec 13, 2021, 6:19 PM Julian Perry <jp_at_digitaltapestries.com> wrote:

> There is one difference between SEQ and PRG files when writing out that
> I've noticed. I don't know whether it has to do with filetype, or the
> secondary address used when opening the file for write, but I noticed a
> difference in the way the files are written out on the 1541 (at least).
> When SAVING a PRG file, the drive just writes out the file, only updating
> the BAM when the save is complete, and the file handle closed.
> When WRITING a SEQ file, however the behaviour is different. The drive
> fills a track with data from the file, but before stepping to the NEXT
> track to continue writing, the head moves back to track 18 (presumably to
> update the BAM).
>
> As I said, I haven't ever been sufficiently curious as to plough through
> the drive code to see whether it's a secondary address function, or a
> PRG/SEQ file type distinction that triggers this difference in behaviour. I
> suppose just writing out a seq file as a PRG filetype (,P,W) would show
> that, too: might try that later.
>
> Anyone else notice this?
>
>
Received on 2021-12-14 02:00:02

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