[Coco] CoCo 'Extended ADOS 3'--How do I get this working?

Sat Sep 2 13:01:17 EDT 2017

On Sat, Sep 2, 2017 at 11:19 AM, Al Hartman <alhartman6 at verizon.net> wrote:

> I am pretty sure that one of the computer tech guys in Australia has
> created an FD-503 replacement board.
>

I am pretty sure that was a FD-502 reproduction unless it is another board
I haven't seen.

The one problem you will run into with changing how the hardware works
compared to how Tandy designed it is compatibility with games or software
that has their own direct floppy disk controller routines built into them.
 That has been a long standing problem with some games or software that
people have wanted to put onto things like a HDD under RGBDOS or HDBDOS.

There have been patches for Disk Basic for 40 and 80 track drives in the
past, but still keeping it single sided of course.  The one problem you run
into if you want to take those disks to a friend and they are using a
standard setup they will not be able to access any files past track 35 on
their standard Disk Basic.  Which is one of the things that causes
compatibility problems.

For compatibility RGBDOS/HDBDOS virtual drives themselves are also setup as
35 track chunks that way you can backup between real 35 track floppies and
the virtual Disk Basic drives on the HDD.  This is also how it is done on
DriveWire as well for floppy disks is in 35 track chunks when using HDBDOS.

This is one of the things that must be carefully weighed when trying to go
outside the box.  When you go outside the box what will and what will not
work with stuff.

Now I am not saying don't make/design new hardware.  Heck, I would love to
see a HD Floppy Controller for the CoCo.  Though for me that would be
something great to have under NitrOS-9. :P

>
> -[ Al ]-
> On 9/2/2017 8:17:13 AM, Francis Swygert <farna at att.net> wrote:
> The biggest challenge with making DECB access larger floppies is that it
> must still be capable of reading smaller capacities also... or at least it
> used to be. For a custom configuration you can change it, but then wouldn't
> be able to access older floppies. You can put two different configurations
> in a disk controller and physically switch between the ROMs, but not "on
> the fly". You'd have to reboot after switching. That could be a reasonable
> alternative to most, just use the second configuration (for lower capacity
> drives) when copying disks. If that were the only function, several DECB
> commands could be eliminated to make room for the drive operations in the
> custom ROM.
>
> The other challenge is the controller itself. 720K drives are the most the
> common controller will handle due to the chip used. I don't think there is
> a pin compatible controller chip that can be substituted that will handle
> 1.44M drives. A new controller compatible with the older formats (including
> SS35T) would need to be made first. If it could be done at a reasonable
> price that would be great, but with DriveWire and the CoCo SDC I'm not sure
> it is really necessary. A cheap, older PC clone running DriveWire can
> access a 1.44M drive easily and cheaply. Once the boot for the PC is
> straightened out it can even be run "headless" -- no keyboard or monitor --
> though that might limit operations (I've never run DriveWire... I think it
> can be run headless though...) Frank Swygert
> Fix-It-Frank Handyman Service
> 803-604-6548
>
> --
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> Coco at maltedmedia.com
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>
> --
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> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco
>

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| David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
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| Do you have your CoCo 3 yet?                                          |
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