Re: 65c02 in Apple][

[mjmahon@aol.com (Michael J. Mahon)]

Bill Garber replied:

>"Michael J. Mahon" <mjmahon@aol.com> wrote in message
>20040520220343.07961.00000938@mb-m04.aol.com">news:20040520220343.07961.00000938@mb-m04.aol.com...
>: Bill Garber wrote:
>:
>: >"Michael J. Mahon" <mjmahon@aol.com> wrote in message
>: >20040520122305.07718.00000774@mb-m24.aol.com">news:20040520122305.07718.00000774@mb-m24.aol.com...
>: >: Bill Garber wrote:
>: >:
>: >: >I just tried it in the setup I have that it works in,
>: >: >and although it tries to boot, it says:
>: >: >"Unable To Load ProDOS".
>: >:
>: >: Then you've succeeded.
>: >:
>: >: That message comes from the ProDOS boot block,
>: >: and indicates that you don't have ProDOS in the
>: >: root directory.
>: >
>: >Then I have failed, as ProDOS "does" exist in the
>: >disks root directory, and will boot with Cs07 at
>: >"00" and by resetting and typing "PR#s". Would
>: >you possibly have an explanation for that? Maybe
>: >I need to reformat the volume and rewrite the
>: >files to it again.
>:
>: What I meant was that in order to get to that message,
>: your machine had to run a fair number of instructions
>: correctly.
>
>Yep, I knew what you meant, and thought that
>I had implied as much. sorry if I didn't.
>
>: A possible explanation is that the boot block code
>: contains some code that does not work correctly.
>
>That is possible, and I'm working with Rich now
>on the 6502 coding, and have gotten to the point
>above with the 6502 and no SpeedDemon.
>
>: Marginal timing could cause such an effect, but it
>: is wierd that it is repeatable.
>
>What is really weird, is that I have the exact problem
>now, but I know why it won't boot. The blocks are all
>marked as used, and none free. Hope all that is is a
>timing issue. Got any ideas for us?

I'm not sure I understand--the boot process doesn't
look at the allocation bitmap.  It just reads in the
directory and scans for "PRODOS".

If (I expect that) they are _not_ really all allocated,
then perhaps you are saying that when you read the
bitmap, it _looks_ all allocated, which would correspond
to a failed "read" of the block.

...but to do that would imply that you've gotten further
than just reading in the boot block. ??

-michael

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