Reading 2732 on breadboard

[hendersonn]

Hello,

As a weekend project I've been trying to get a 28C64 working with on recycled Pac-Man cart board. I'm under the assumption the original PROM used was the 2732 based on a few text documents sprinkled on the web. The idea was to solder some jumpers to the cart's bare PCB, which in tern would be connected to a breadboard. As a test, I reinserted the 2732 onto the breadboard and successfully ran Pac-Man. Next I tried replacing the 2732 with the 28C64 and rewiring as needed to no success. The 28C64 has two copies of Pac-Man written to it, I have confirmed this with several tests: I can play the doubled Pac-Man ROM image in Stella, I have compared both the doubled and the original PROM image in a hex editor, as well manually checking the first few addresses of the 28C64 (by connecting the data bus to LEDs and grounding the appropriate address- comparing the LED output with the hex editor). All this makes the think the 28C64 is working as it should; when I try to manually read the 2732 in a similar fashion, I get no activity on the data bus. I'm curious if this is even a 2732 at all, maybe I have the address lines mixed up. I've confirmed that the (assumed) 2732 isn't fried multiple times as well, just to make sure. I must be missing something silly, hopefully you guys/gals can point me in the right direction.

 

Thanks.

 

tl;dr I'm trying to connect a 28C64 EEPROM to a Pac-Man board with the assumption that Pac-Man uses a 2732 PROM to no avail.

** I've searched the forums and google- but nothing turns up complete solutions.

[CPUWIZ]

Pull the high address line to GND and invert the chip select, with a 7404.

[hendersonn]

15 minutes ago, CPUWIZ said:

Pull the high address line to GND and invert the chip select, with a 7404.

Is this for the 28C64 or the 2732? I'd like to start by reading the latter on a breadboard via LEDs first. I'm also a little confused as both chips' datasheets refer to the chip select line as being active low; not to mention the absence of an inverter on the original cart.

[CPUWIZ]

Atari ROM's have the logic inverted.

[hendersonn]

4 minutes ago, CPUWIZ said:

Atari ROM's have the logic inverted.

Interesting, I must have missed that somewhere. That aside, I can assume the data and address lines are the same?

[CPUWIZ]

 

[hendersonn]

Aw nuts, guess I didn't go back far enough. Thanks a bunch, I think I have what I need now.