Problem with my first cart

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Problem with my first cart
by lordloss on 2011-10-25 (#85589)
I am making a repro of Drac's Night Out and I got everything flashed and wired up only to see a purple screen. Can anyone tell me from this description if its a wiring problem, or a chip problem?

I will post pics of my wiring as soon as my camera battery has finished charging.

by lordloss on 2011-10-25 (#85590)
Here is a pic of my wiring. As you can see, I am using SLROM with two OTP EPROMS m27c1001.

http://i.imgur.com/69G82.jpg

by 80sFREAK on 2011-10-25 (#85595)
Ummm not the best photo, you should switch off flash. I guess IC's are the same, so timings not an issue. Purple screen - check wiring(and datasheet) of PRG-ROM and IC by itself. Ah, you should put IC's on the socekts :?

by lordloss on 2011-10-25 (#85596)
IC's on the socket? I put both chips into their sockets, is this wrong?

by lordloss on 2011-10-25 (#85597)
http://imgur.com/a/Q8SUp

by lordloss on 2011-10-25 (#85599)
Ok, maybe I went straight stupid and completely ignored the pin layout for the right chip.

by 80sFREAK on 2011-10-26 (#85608)
Why pin 1 is not connected?

by infiniteneslives on 2011-10-26 (#85609)
80sFREAK wrote:
Ummm not the best photo, you should switch off flash. I guess IC's are the same, so timings not an issue.


Why would differences in timing between the two chips matter???

80sFREAK wrote:
Why pin 1 is not connected?


It's the Vpp pin. Shouldn't matter what it is, but it's not a great idea to leave pins floating. I would just wire it up to Vcc.

lordloss wrote:
Ok, maybe I went straight stupid and completely ignored the pin layout for the right chip.


It's hard to see exactly what you're doing but it doesn't look like you wired up either of them correctly... You need to look up the pinout of the original rom including the address lines and connect accordingly.

I recommend drawing it out and everything first.

If you still can't get it going maybe the answers are in that book under the cart ;)

by 80sFREAK on 2011-10-26 (#85615)
lordloss wrote:
http://imgur.com/a/Q8SUp
RTFM! :evil:

by lordloss on 2011-10-26 (#85656)
I fixed it and got it working. I stupidly did not connect vcc to one of the chips miswired another. I think it was only two wires that needed changing, maybe three. It works now so I am happy.