[Coco] Coco Digest, Vol 166, Issue 36

[Arthur Flexser]

There's quite a few places that need to be patched, though for your
purposes, you probably need to patch only the main DSKCON routine that does
sector reads and writes.

Perhaps someone here can point to a file that contains the necessary fixes.

Be aware that you'd need one set of fixes for Disk Basic 1.0 and an
entirely different set for DIsk Basic 1.1.  I don't think it's worth the
trouble, since disk i/o speed is limited in any case by the rotational
speed of the floppy, so gains from going to double speed for disk i/o would
be minimal, mainly from occasionally saving an extra rotation to get the
required sector under the drive head, which saves 0.2 seconds.  Better to
just drop the CoCo 3 back to single speed temporarily when disk i/o is
needed.

Art

On Thu, Aug 25, 2016 at 4:54 AM, Pere <psergm at gmail.com> wrote:

> Hi Art,
> I am new to the CoCo developpment arena and know just a few about the
> CoCo3.
> As the POKE&HFFD7,0 works well in CoCo and Dragon I thought that issuing
> the
> double speed for the CoCo3 would work well ... in fact the tests I have
> done, have
> been made on VCC, so I cannot speak about the real thing.
> VCC supports well that double speed, the images are loaded faster without
> problems.
> If it were just a matter of changing (doubling) the value of a few bytes
> to compensate
> for the double speed, I could add these changes. Could you give me any
> pointer to
> know what places should be modified (for reading and writting)
> The program calls the FREE, CLOSE and LOF commands too
> Thanks in advance
> pere
>
> -----Mensaje original----- Message: 4
> Date: Wed, 24 Aug 2016 18:14:23 -0400
> From: Arthur Flexser <flexser at fiu.edu>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Subject: Re: [Coco] The Hobbit ported to 6809 (Dragon64 and coCo2 64k)
> Message-ID:
> <CA+LuDcc=ZU1g6e4kaCqDcQ+Odg_qMBsf6rOM03WVTX6YwVRCbg at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> This sounds like a bad idea if you are doing disk I/O at double speed.  The
> CoCo 3's disk routines must be modified to do this reliably, on account of
> insufficient delays at double speed.
> Art
>
>
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