[A89] Re: Disabling 'Protection'
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[A89] Re: Disabling 'Protection'
Hey, I didn't know you could disassemble TI-89 programs, but that still
doesn't help (right now, I may be able to stare at it long enough).
-MrM
On Tue, 27 May 2003 00:02:09 -0700 (PDT), Laine Walker-Avina
<nerdguy0@yahoo.com> wrote:
> --- Matthew Mullins <mokomull@cox-internet.com> wrote:
>> I got that already; I just can't figure out how the
>> 'instructions' are used!
>>
>> -MrM
>> ----- Original Message ----- From: Laine Walker-Avina To: mokomull@cox-
>> internet.com Sent: May 26, 2003 2:29 PM
>> Subject: Re: [A89] Disabling 'Protection'
>>
>>
>> --- Matthew Mullins wrote:
>> > I am trying to port HW2Patch to AMS 2.08/2.09. I
>> figured
>> > out the I/O ports I need to change (0x700000 and
>> > 0x700004, lwords), but I can't figure out how to
>> disable
>> > the Protection on HW2 calculators. Can anybody give
>> me a
>> > tip to disabling it?
>> > > -MrM
>> From http://tict.ticalc.org/docs/J89hw.txt:
>>
>>
>> $1C0000-$1FFFFF: "the Protection" enable/disable
>> Note: Four consecutive accesses to this range crashes a
>> HW1 calc!
>> READ: Enable the Protection
>> WRITE: Disable the Protection
>> Note: No access to this range will have any effect unless
>> the access is
>> "authorized," see below.
>>
>> $200000-$20FFFF,
>> $212000-$217FFF,
>> $21A000-$21FFFF: "the Protection" access authorization
>> HW1:
>> In order to alter the state of the Protection, THREE
>> consecutive read
>> accesses must occur from any of the three ranges above
>> immediately prior
>> to the access to the Protection enable/disable range.
>> HW2:
>> (Note: This is somewhat complicated and I don't know
>> exactly how it works.
>> The procedure listed below is probably too strict. Anyway, this is what
>> AMS and the boot sector does.)
>> In order to alter the state of the Protection, (at
>> least) SEVEN supervisor
>> instruction fetches must occur from any of the three
>> ranges above prior to
>> the access to the Protection enable/disable range. The
>> choice of
>> instructions is not arbitrary, it must be one of the
>> following sequences:
>> * To DISABLE the Protection: $4E71, , $4E71, $4E71,
>> $46FC, $2700, $3080, . The very next access must be the
>> WRITE to the Protection enable/
>> disable range.
>> * To ENABLE the Protection: $4E71, , $4E71, $4E71,
>> $46FC, $2700, $3010, . The very next access must be the
>> READ from the Protection
>> enable/disable range.
>> ($4E71="nop", $46FC="move #imm16,sr", $3080="move.w
>> d0,(a0)",
>> $3010="move.w (a0),d0")Laine
>
> It looks to me like you'd have to read those seven values
> consecutively to disable the protection. Also be sure that
> that's the only thing being accessed at the time. I believe
> earlier in the document it says that you must disable the
> LCD controller from accessing the the video memory because
> it causes a bus operation. Anyhow, if you can't get it to
> work that way you can try and see what hw2patch is doing.
> I've attached a copy of it, disassembled, in cause you wish
> to go that route.
> Best of luck!
> Laine
>
> =====
> Laine Walker-Avina
> nerdguy0@yahoo.com
>
> In /dev/null, no one can hear your stream.
>
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