Test: the stack

Marc S. Ressl

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Feb 12, 2012, 11:10:21 PM2/12/12

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As it seems to be fashionable these days to ask about the Apple II
computers (*wink*), here goes another question: could somebody with an
Apple II plus start it up, press RESET and type the following?

]CALL -151
*100.17F

And tell me if the byte at $0100 is $FA, and the next bytes tend to
follow the pattern "$FF $FF $00 $00"?

Thanks!

Marc.-

BLuRry

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Feb 13, 2012, 12:12:50 AM2/13/12

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There is a good chance of it -- the //e tends to start off with a pattern like the one you're asking about, and that's also why it has vertical white and black stripes when it turns on briefly (hires mode).

-B

Vladimir Ivanov

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Feb 13, 2012, 7:29:00 AM2/13/12

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As for startup pattern, it's not something you can count on. Whatever the
emulator choice, it will be wrong and misleading. ;-)

All zero seems best to me.

Vladimir Ivanov

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Feb 13, 2012, 7:34:59 AM2/13/12

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On Sun, 12 Feb 2012, Marc S. Ressl wrote:

BTW, quickly tested IIc (A2S4000) starts mostly with $00 $FF $00 $FF in
main memory.

Daniel Kruszyna

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Feb 13, 2012, 7:37:24 AM2/13/12

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Vladimir Ivanov <vla...@xxxyahooxxx.com> wrote:
>
>> And tell me if the byte at $0100 is $FA, and the next bytes tend to
>> follow the pattern "$FF $FF $00 $00"?
>
> As for startup pattern, it's not something you can count on. Whatever the
> emulator choice, it will be wrong and misleading. ;-)

In that case, make it random :)

-- Daniel

D Finnigan

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Feb 17, 2012, 5:20:04 PM2/17/12

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For me, no. I am on my iPod touch now, and as soon as I can, I will upload a
picture that I took of the screen.

To the best of my memory, the pattern was FF FF 00 02.

--
]DF$
Mac GUI Vault - A source for retro Apple II and
Macintosh computing.
http://macgui.com/vault/

Antoine Vignau

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Feb 17, 2012, 5:42:24 PM2/17/12

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I knew I forgot to add an (un*)interesting comment in a thread :-)
- I can't tell about 8-bit machines right now, I have a II europlus
and a Laser 128 somewhere in my room, I'll try to turn them on and
tell you about that. IIRC, the first byte of each 4 KB is reset.

- I will tell about the IIgs (ROM 01 & 3). The main difference is
between the cold start and the warm start. A warm start inits banks
$00/$01 and $E0/$E1 whereas a cold start inits all banks.

I understand the concern about the memory re/set of the Apple II but
why do you focus on the stack area? I would understand some questions
about the $01F0..$01FF area but why the last part of the stack?
LIFO...

Antoine

* - feel free to =xXXXx=

Bill Hicks

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Feb 18, 2012, 6:42:27 AM2/18/12

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On my laser 128 when I boot ADT 2.4 I get

00 00 FF FF FF FF 00 00

It seems to repeat, 4 bytes of 0 and then 4 bytes of 255

If I boot prodos I get the same pattern and if I boot with no disk

On different topic, anyone know of a good reader for the iPad so I
don't have to use google groups and get ignored by people?

Bill

D Finnigan

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Feb 18, 2012, 11:52:44 AM2/18/12

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OK, here is the picture:

http://macgui.com/gallery/showphoto.php?pic_id=1543

*100.17F

0100- FF FF 02 00 FF FF 02 00
0108- FF FF 02 00 FF FF 02 02

It's an interesting pattern. There's more to it than just those two lines.

Bill Hicks

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Feb 18, 2012, 5:02:50 PM2/18/12

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Why is there a pattern? Is it initialized to that for some reason? And
why is your different?

Michael J. Mahon

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Feb 18, 2012, 9:28:57 PM2/18/12

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Bill Hicks <billw...@gmail.com> wrote:
> On Feb 18, 11:52 am, dog_...@macgui.com (D Finnigan) wrote:
>> OK, here is the picture:
>>

>> http://macgui.com/gallery/showphoto.php?pic_id 43

>>
>> *100.17F
>>
>> 0100- FF FF 02 00 FF FF 02 00
>> 0108- FF FF 02 00 FF FF 02 02
>>
>> It's an interesting pattern. There's more to it than just those two lines.
>>
>> --
>> ]DF$
>> Mac GUI Vault - A source for retro Apple II and
>> Macintosh computing.http://macgui.com/vault/
> Why is there a pattern? Is it initialized to that for some reason? And
> why is your different?

It's the way the DRAMs power up in an Apple when they've been off for a
while. No great significance.

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon

Marc S. Ressl

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Feb 19, 2012, 1:07:06 AM2/19/12

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On 18 feb, 23:28, Michael J. Mahon <mjma...@aol.com> wrote:

Thanks a lot for all the great responses!

Yes, indeed it is something of no importance, except for the tiny
flash of graphic characters you see when starting a computer.

Also, I was interested in what happens in the stack at 0x100, because
of a peculiarity of how the 6502 starts up. And indeed it proved me
wrong, it seems the stack is not initialized at 0x00, but rather 0xff.

Thanks again for all the help,
and with the best wishes,

Marc.-

pd: the Laser and IIGS responses were particularly interesting to me :)

Anthony Lawther

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Feb 19, 2012, 3:14:22 PM2/19/12

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NewsTap works really well for the iPod Touch.
>
> Bill