7800 eprom cart?

[chriswhit]

I have a bunch of CA024927 rev A pcb's and I'm wondering If I can use these with 28 pin 2764 eproms to make 32k home brew carts for my 7800? Where do I find info on this?

[Shawn]

I have a bunch of CA024927 rev A pcb's and I'm wondering If I can use these with 28 pin 2764 eproms to make 32k home brew carts for my 7800? Where do I find info on this?

 

Yes you can use those boards but 2764 is only 8K you will need 27256 eproms for 32k games. You will also need to add in inverter (74ls04 or similar) to the output enable line to go from the eprom to the pcb. To make things a little easier for you untill you know more about how eproms work the OE is pin 22 on your eprom or just count 7 legs from the bottom right of the eprom with the groove on the eprom also facing right. You will need to bend the leg up to attach it to your inverter chip. When you hook up the inverter (say it's a 74ls04) you will need pins 1,2,7,14. 1 is input, 2 is output, 7 is gound, 14 is 5V. They will all need to be attached. The input and output lines on the inverter go to pin 22 of the eprom and the hole on the pcb under it. 5V (pin 14) goes to pin 28 of the pcb, GND (pin 7) goes to pin 14 of the pcb.

[chriswhit]

I have a bunch of CA024927 rev A pcb's and I'm wondering If I can use these with 28 pin 2764 eproms to make 32k home brew carts for my 7800? Where do I find info on this?

 

Yes you can use those boards but 2764 is only 8K you will need 27256 eproms for 32k games. You will also need to add in inverter (74ls04 or similar) to the output enable line to go from the eprom to the pcb. To make things a little easier for you untill you know more about how eproms work the OE is pin 22 on your eprom or just count 7 legs from the bottom right of the eprom with the groove on the eprom also facing right. You will need to bend the leg up to attach it to your inverter chip. When you hook up the inverter (say it's a 74ls04) you will need pins 1,2,7,14. 1 is input, 2 is output, 7 is gound, 14 is 5V. They will all need to be attached. The input and output lines on the inverter go to pin 22 of the eprom and the hole on the pcb under it. 5V (pin 14) goes to pin 28 of the pcb, GND (pin 7) goes to pin 14 of the pcb.

Thanks for the info. This will help a lot.

[chriswhit]

I have a bunch of CA024927 rev A pcb's and I'm wondering If I can use these with 28 pin 2764 eproms to make 32k home brew carts for my 7800? Where do I find info on this?

 

Yes you can use those boards but 2764 is only 8K you will need 27256 eproms for 32k games. You will also need to add in inverter (74ls04 or similar) to the output enable line to go from the eprom to the pcb. To make things a little easier for you untill you know more about how eproms work the OE is pin 22 on your eprom or just count 7 legs from the bottom right of the eprom with the groove on the eprom also facing right. You will need to bend the leg up to attach it to your inverter chip. When you hook up the inverter (say it's a 74ls04) you will need pins 1,2,7,14. 1 is input, 2 is output, 7 is gound, 14 is 5V. They will all need to be attached. The input and output lines on the inverter go to pin 22 of the eprom and the hole on the pcb under it. 5V (pin 14) goes to pin 28 of the pcb, GND (pin 7) goes to pin 14 of the pcb.

Will it matter if I use a 27c256 instead of a 27256 eprom? The price I found on 27c256 is far cheaper than the other

[Wickeycolumbus]

I have a bunch of CA024927 rev A pcb's and I'm wondering If I can use these with 28 pin 2764 eproms to make 32k home brew carts for my 7800? Where do I find info on this?

 

Yes you can use those boards but 2764 is only 8K you will need 27256 eproms for 32k games. You will also need to add in inverter (74ls04 or similar) to the output enable line to go from the eprom to the pcb. To make things a little easier for you untill you know more about how eproms work the OE is pin 22 on your eprom or just count 7 legs from the bottom right of the eprom with the groove on the eprom also facing right. You will need to bend the leg up to attach it to your inverter chip. When you hook up the inverter (say it's a 74ls04) you will need pins 1,2,7,14. 1 is input, 2 is output, 7 is gound, 14 is 5V. They will all need to be attached. The input and output lines on the inverter go to pin 22 of the eprom and the hole on the pcb under it. 5V (pin 14) goes to pin 28 of the pcb, GND (pin 7) goes to pin 14 of the pcb.

Will it matter if I use a 27c256 instead of a 27256 eprom? The price I found on 27c256 is far cheaper than the other

 

Yes, you can use a 27c256.

[chriswhit]

I have a bunch of CA024927 rev A pcb's and I'm wondering If I can use these with 28 pin 2764 eproms to make 32k home brew carts for my 7800? Where do I find info on this?

 

Yes you can use those boards but 2764 is only 8K you will need 27256 eproms for 32k games. You will also need to add in inverter (74ls04 or similar) to the output enable line to go from the eprom to the pcb. To make things a little easier for you untill you know more about how eproms work the OE is pin 22 on your eprom or just count 7 legs from the bottom right of the eprom with the groove on the eprom also facing right. You will need to bend the leg up to attach it to your inverter chip. When you hook up the inverter (say it's a 74ls04) you will need pins 1,2,7,14. 1 is input, 2 is output, 7 is gound, 14 is 5V. They will all need to be attached. The input and output lines on the inverter go to pin 22 of the eprom and the hole on the pcb under it. 5V (pin 14) goes to pin 28 of the pcb, GND (pin 7) goes to pin 14 of the pcb.

Will it matter if I use a 27c256 instead of a 27256 eprom? The price I found on 27c256 is far cheaper than the other

 

Yes, you can use a 27c256.

Thank you