Help to find mistake for Circuit with NO SRAM

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poorstudenthobbyist
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Joined: Fri Jun 24, 2016 4:20 pm

Re: Help to find mistake for Circuit with NO SRAM

Post by poorstudenthobbyist »

I believe he's using the two muxes for changing the 16 bit output of the 322 to 8 bits, like this.
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Fisher
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Re: Help to find mistake for Circuit with NO SRAM

Post by Fisher »

Oops!
Looks like I misread it again.
I saw each mux selecting 8 bits out of 16, but in fact they're selecting 4 ou of 8. :oops:
Kayumba
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Re: Help to find mistake for Circuit with NO SRAM

Post by Kayumba »

poorstudenthobbyist wrote: Mon Apr 19, 2021 9:33 am I believe he's using the two muxes for changing the 16 bit output of the 322 to 8 bits, like this.
Yes poorstudenthobbyist.
Kayumba
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Re: Help to find mistake for Circuit with NO SRAM

Post by Kayumba »

Still have a BUS conflicts :?
Dont understand...
Was trying to follow poorstudenthobbyist explainer but with no success.
Sometime game start but after some minutes I get BUS conflicts.
Can somebody give me solution please?

CARTRIDGE EDGE pin 49 "/CART" =>
CARTRIDGE EDGE pin 23 "/RD" =>
Multiplexers 74HC257D pin 15 "OE" =>
EPROM pin 11 "CE" =>
EPROM pin 13 "OE" =>
poorstudenthobbyist
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Re: Help to find mistake for Circuit with NO SRAM

Post by poorstudenthobbyist »

How do you know it's a bus conflict?
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: Help to find mistake for Circuit with NO SRAM

Post by Kayumba »

poorstudenthobbyist wrote: Sun May 16, 2021 10:35 am How do you know it's a bus conflict?
I think so.

- Eprom work’s fine on other boards.
- Pinouts for adresses and data’s are the same.
- Pinouts for Multiplexers are the same (except OE)

As you said ;

« bus conflicts. If you’re going to use a 27C322, or any 16-bit data bus device, and use multiplexers to change that 16-bit data bus to an 8-bit data bus, you’ve got a new set of /OE pins »

I think only Enable Pins can be suspected .


You think that it can be something else ?
poorstudenthobbyist
Posts: 252
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Re: Help to find mistake for Circuit with NO SRAM

Post by poorstudenthobbyist »

Just because the game stops working doesn't mean it's a bus conflict. That's just one of many things that could be going wrong. And in my experience, bus conflicts manifest errors quite quickly rather than letting the game run for a while.

Think through why you are connecting things where you are, and what the differences are (why do you wire the board differently with SRAM and without for example), and you'll know if there is a bus conflict that's possible. If there isn't, your error must be elsewhere.

The important point to remember is that bus conflicts arise when multiple things are trying to drive a single line to different levels. Do you expect that to happen with your wiring?
Kayumba
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Re: Help to find mistake for Circuit with NO SRAM

Post by Kayumba »

poorstudenthobbyist wrote: Sun May 16, 2021 3:58 pm Just because the game stops working doesn't mean it's a bus conflict. That's just one of many things that could be going wrong. And in my experience, bus conflicts manifest errors quite quickly rather than letting the game run for a while.

Think through why you are connecting things where you are, and what the differences are (why do you wire the board differently with SRAM and without for example), and you'll know if there is a bus conflict that's possible. If there isn't, your error must be elsewhere.
Thanks for helping me 🙏

Will continue to search 🔦
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