what is used on a atari 7800 for a chip enable signal for an 7800 cartridge rom ?
Thelen
0
atari 7800 chip enable
Started by Thelen, Mar 10 2003 2:28 PM
5 replies to this topic
#2 OFFLINE
CPUWIZ
-
-
- 26,327 posts
Rarity 11
- Cartridge Recycler
- Location:SoCal
Posted Mon Mar 10, 2003 2:36 PM
The CE line is active high, in order to use EPROM's you'd need to invert it.
#3 OFFLINE
Mitch
-
-
- 5,769 posts
Quadrunner
- 7800 Guy
- Location:Southern California, USA
Posted Mon Mar 10, 2003 2:39 PM
CPUWIZ said:
The CE line is active high, in order to use EPROM's you'd need to invert it.
Actually this is only true for the 16/32k EPROMS. The 64/128K EPROMS don't need an inverter.
Mitch
#4 OFFLINE
Thelen
-
-
- 530 posts
Dragonstomper
- Location:Holland
Posted Mon Mar 10, 2003 3:45 PM
so is it A12 on the cartridge port ? or is that only in 2600 mode ?
Thanks, Thelen
Thanks, Thelen
#5 OFFLINE
Thelen
-
-
- 530 posts
Dragonstomper
- Location:Holland
Posted Mon Mar 10, 2003 4:15 PM
I have found out already : A14 OR a15 high means that CE is active....
Thanks, Thelen
Thanks, Thelen
#6 OFFLINE
DanBoris
-
-
- 930 posts
Dragonstomper
- Location:New Jersey, USA
Posted Mon Mar 10, 2003 5:55 PM
The 7800 doesn't actually have a chip select line that goes to the cartridge. All the address lines are brought out to the cart and it's up to the cart to decode them and enable the ROM in the appropriate address range.
Dan
Dan
1 user(s) are reading this topic
0 members, 1 guests, 0 anonymous users
