[atari7800] Re: [personal] Re: AW: 7800 cartridge detection

  • From: "Dan Boris" <dboris@xxxxxxxxxxx>
  • To: <atari7800@xxxxxxxxxxxxx>
  • Date: Wed, 10 Aug 2005 18:35:58 -0400

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.

-----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  <mailto:matthias@xxxxxxxxxxxx> 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

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 ?



Other related posts: