[Coco] Drive controller problem

[Arthur Flexser]

That is indeed very confusing:  If I understand you correctly, everything
works okay with the HDBDOS ROM, which means the controller is okay.  And
the Disk Basic startup message (followed by an OK prompt and a blinking
cursor, right?) comes up okay, which almost certainly rules out a problem
with the Disk Basic ROM.

Can you describe exactly what happens when you attempt a disk operation?
Does the drive light come on?  Is an ?IO ERROR message what you're seeing
on attempted reads and writes?

Are you using the correct Disk Basic syntax, and not some command that is
only legal under HDBDOS?  (In which case, you'd be getting a ?SN ERROR, not
the ?IO ERROR.)

What happens when you try to DSKINI a disk?  Do you hear the head returning
to Track 0 after the initial pass to begin the verify pass, and then see an
immediate ?IO ERROR when it fails to verify Track 0?

Again, I recommend cleaning the edge connector contacts, since oxidation
there can cause many head-scratching intermittent problems.

Art


On Thu, Apr 3, 2014 at 5:07 PM, Bill <cwgordon at carolina.rr.com> wrote:

> Tested out the HDBDOS chip, and it works great. However, when the Tandy
> chip
> is re-inserted, it still will not read or write to a known-good drive or
> disk. Tried the ?PEEK(&HC000) and got the same results, but when I try to
> USE the controller with the Tandy chip in it, it doesn't work at all.
> (That's what made me think that the controller was bad. Now I'm not sure if
> it's the controller or the chip.)
>
> Getting more confused as I go :(
>
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com]
> On
> Behalf Of Bob Devries
> Sent: Tuesday, April 01, 2014 5:17 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Drive controller problem
>
> Bill,
>
> Can you check the first two bytes at $C000 when the HDBDOS ROM is inserted?
> They should be $444B(68, 75 decimal). If that's not what you get, your ROM
> is bad.
>
>
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