Re: 65c02 in Apple][

["Bill Garber" <willy46pa@comcast DOT net>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message
20040521025434.08010.00000943@mb-m04.aol.com">news:20040521025434.08010.00000943@mb-m04.aol.com...
: 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. ??

Rich is now attributing it to a timing difference in
the relationship of /DEVSEL to 7M in the II+. With the
modifications in firmware to 6502 code it now works in
a non-enhanced IIe with no 80col/64K card. Making some
progress.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy46pa @ comcast DOT net
Change DOT to a dot to contact me



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