Soooo, I have a great big bag of AY-3-8912A sound chips which all appear to work great everywhere else I’ve used them, but fail to work in either my Oriclone-1 project (much to my dismay) or a real Oric. I had to borrow an AY-3-8912 non A version when I found that my Oriclone-1 keyboard was misbehaving.
Why is this so?
It’s worth knowing as the ‘A’ version is cheaper and much more available.
AY-3-8912 compatibility.
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- 2nd Star Corporal
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Re: AY-3-8912 compatibility.
Not sure if relevant:
https://atariage.com/forums/topic/24734 ... y-3-8912a/
https://atariage.com/forums/topic/24734 ... y-3-8912a/
The difference between the 8912A and 8912 is the A does not have internal pull up resistors on the output port. I'm not sure if this makes a difference with the vectrex.
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- 2nd Star Corporal
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Re: AY-3-8912 compatibility.
That thought occurred to me too, so I added a SIP resistor pack to the side of one of the AY-3-8912A’s and it made no difference.
Just for kicks, I even moved the common lead to the other supply rail and it still made no difference. Thus, the pull-ups don’t matter. It appears the Oric uses this port only as an output. I think there may be a timing issue here as the newer part is noticeably faster according to the data sheets.
Thank you for the suggestions and links however. I’m still sure to learn something from them.
P.S. I’ll be spinning a new PCB revision on my Oriclone-1 to address early design issues soon, but if anyone wants the leftover unpopulated ones, they’re welcome to them. There’s precious little needed to get them essentially working.
Just for kicks, I even moved the common lead to the other supply rail and it still made no difference. Thus, the pull-ups don’t matter. It appears the Oric uses this port only as an output. I think there may be a timing issue here as the newer part is noticeably faster according to the data sheets.
Thank you for the suggestions and links however. I’m still sure to learn something from them.
P.S. I’ll be spinning a new PCB revision on my Oriclone-1 to address early design issues soon, but if anyone wants the leftover unpopulated ones, they’re welcome to them. There’s precious little needed to get them essentially working.
Re: AY-3-8912 compatibility.
Regarding the joystick ports, I concur with the ones who mentioned making it IJK compatible, it's the current standard everybody agreed on, and for which games have been patched.
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- 2nd Star Corporal
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Re: AY-3-8912 compatibility.
How does one scan an IJK joystick. As it should be added to the mainboard, and that means 5V and suchlike being very readily available, I see no reason why we can’t have our cake and eat it (auto-fire ahoy!).
This also opens up the printer port with say, a simple switch.
This also opens up the printer port with say, a simple switch.
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- 2nd Star Corporal
- Posts: 31
- Joined: Sun Jan 05, 2020 2:38 pm
- Location: Leicester, UK
Re: AY-3-8912 compatibility.
I just found the IJK details, and so now implementing an internal interface should be practical.