Re: ProDOS 1.3 bug (was: Re: Apple IIe + ProDOS = Headache)

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

"Matthew W. Miller" <mwmiller@columbus.rr.com> wrote in message
slrnce8iqf.1cc.mwmiller@dhcp065-024-101-200.columbus.rr.com">news:slrnce8iqf.1cc.mwmiller@dhcp065-024-101-200.columbus.rr.com.
..
: On Fri, 25 Jun 2004 11:38:26 -0400, Bill Garber
<willy46pa@comcast> wrote:
: > "David Wilson" <david@uow.edu.au> wrote in message
: > news:40db968f$1@news.uow.edu.au...
: >: P8 v1.3 works fine on an Apple II with 65C02 CPU. If you run
it
: >: on an unenhanced IIe or a II or II+ with a 6502 CPU and that
bad
: >: instruction is executed the 6502 will NOT branch like the
code
: >: expects but will instead fall through into disk writing code
and
: >: overwrite data on your diskette.
: > Therefore it would either be advisable to update all Apple
IIs to
: > 65C02 or eliminate ProDOS version 1.3 altogether.
:
: Those are both rather untenable (yes, I saw the smiley).  The
questions
: I'm wondering are, has anyone managed to isolate that bug in
ProDOS 1.3,
: and if so, has anyone managed to fix it?

Taken from another post in this thread.  :o)

Here is the description as published in Open-Apple v3 n2
March 1987 page 3.12:

 ProDOS 8, version 1.3, released to developers in mid-January
and mentioned here last month, mistakenly includes a BRA (branch
always) machine language instruction in a critical piece of code.
This is a significant problem, because BRA isn't supported by the
original 6502 microprocessor. Consequently, this version of
ProDOS
causes bad things to happen when run on Apple II-Pluses and
unenhanced IIes. If you BLOAD PRODOS,TSYS,A$2000, then the bad
instruction appears at $4CCD. A BEQ (branch on equal) would work
just as well here, so you can fix things with a POKE 19661,240
and a BSAVE PRODOS,TSYS,A$2000.

I personally see no reason for anyone to be running any versions
of ProDOS 8 other than v1.9 on 6502 equipped Apple IIs and v2.0.3
on 65C02 equipped systems. This way you get all the known bug
fixes.

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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