[atari7800] Re: [personal] Re: AW: 7800 cartridge detection
- From: "Kroko" <Nil.Krokodil@xxxxxxx>
- To: <atari7800@xxxxxxxxxxxxx>
- Date: Thu, 11 Aug 2005 18:34:42 +0200
MessageYes, I think you are right. I tested it with connected Krokodile Power
supply. It still runs Asteroids.
And if the Power supply is connected, the Krokdile is active before the 7800.
So that can't be the
problem.
----- Original Message -----
From: Dan Boris
To: atari7800@xxxxxxxxxxxxx
Sent: Thursday, August 11, 2005 2:28 AM
Subject: [atari7800] Re: [personal] Re: AW: 7800 cartridge detection
I guess it's possible the 7800 has a shorter power on delay, but it still
have to run a couple hundred machine cycles before it gets to the validation
routine, so it seams unlikely that your cartridge isn't powering up in time.
Dan
-----Original Message-----
From: atari7800-bounce@xxxxxxxxxxxxx
[mailto:atari7800-bounce@xxxxxxxxxxxxx] On Behalf Of Kroko
Sent: Wednesday, August 10, 2005 6:57 PM
To: atari7800@xxxxxxxxxxxxx
Subject: [atari7800] Re: [personal] Re: AW: 7800 cartridge detection
I was planning to make the Krokodile Cartridge run on a 7800. I plugged in
4 different firmware revisions, even different
board versions which all run 100% OK on my 2600. But all I get in the 7800
is Asteroids :-(
So I need to find out why a 7800 would decide to run Asteroids instead of
running an ordinary PacMan Rom programmed on a
Krokodile Cartridge ... I think that info you just posted already helps:
Could the startup time be a problem ? As there is a microcontroller on the
Krokodile, it is not 100% "instant on". maybe the 7800
starts up more quickly than a 2600 and checks the cart slot at a time where
the Krokodile is not yet ready. Is the 2600 slower ?!
Well, just a first guess ...
I don't think its a dirty slot, because I have quite some 2600 Roms which
run normally (including PacMan) ...
Armin
----- Original Message -----
From: Dan Boris
To: atari7800@xxxxxxxxxxxxx
Sent: Thursday, August 11, 2005 12:35 AM
Subject: [atari7800] Re: [personal] Re: AW: 7800 cartridge detection
This discussion got me thinking that I never actually looked at the PAL
BIOS disassembly. So i did a diassembly and have been trying to figure out how
it works. Here's what I have found so far..
The BIOS compares FE00-FE7F with FE80-FF00 and if they are the same, it
assumes there no cartridge and jumps to internal game.
Next if checks the reset vector, and if it's $FFFF or $0000 then it
assumes there's no cartridge and jumps to the internal game.
It looks like it then checks $FFF8 and $FFF9 for a valid 7800 cartidge
header. If it's not valid it starts the cartridge in 2600 mode.
That's all I have been able to figure out so far.
Dan
-----Original Message-----
From: atari7800-bounce@xxxxxxxxxxxxx
[mailto:atari7800-bounce@xxxxxxxxxxxxx] On Behalf Of Kroko
Sent: Wednesday, August 10, 2005 5:18 PM
To: atari7800@xxxxxxxxxxxxx
Subject: [personal] [atari7800] Re: AW: 7800 cartridge detection
Do you know, how the 7800 detects if a valid cartridge is plugged in ?
----- Original Message -----
From: Matthias Luedtke
To: atari7800@xxxxxxxxxxxxx
Sent: Wednesday, August 10, 2005 11:09 PM
Subject: [atari7800] AW: 7800 cartridge detection
If you have trouble with more than one cartridge than I guess your
7800 have a problem.
----------------------------------------------------------------------
Von: atari7800-bounce@xxxxxxxxxxxxx
[mailto:atari7800-bounce@xxxxxxxxxxxxx] Im Auftrag von Kroko
Gesendet: Mittwoch, 10. August 2005 21:16
An: atari7800@xxxxxxxxxxxxx
Betreff: [atari7800] 7800 cartridge detection
Hi !
I am having trouble with a 7800. How does the 7800 detect that a
cartridge
is plugged into its cartridge port ? It starts up the built in
Asteroids for some of
the cartridges I have here, even if they are plugged in ...
Is the 7800 faulty or the cartridges, or is this a common problem ?
Armin
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