WCLegere Posted June 10 Share Posted June 10 Does anyone know where I can find one of these chips for my system? Thanks in advance. 1 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted June 10 Share Posted June 10 TOS, or QI? ColecoVision, has a SN76489AN. You can use an SN76489AN, in a TOS model, but you'll have to resolder a jumper, as well. 1 Quote Link to comment Share on other sites More sharing options...
WCLegere Posted June 10 Author Share Posted June 10 New to the TI-99/4A so not sure what u mean by TOS or QI. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted June 10 Share Posted June 10 57 minutes ago, WCLegere said: New to the TI-99/4A so not sure what u mean by TOS or QI. Couple of things to note about the sound chip. There are three variants of the chip that were regularly installed in TI consoles, all of which are drop-in replacements for each other. They are the SN94624 in your console, the TMS9919, and the SN76494. All of these chips expect a 500 KHz clock, which the TI provides them. Here is where it gets interesting. There are also two compatible chips that include divide-by-8 circuitry on the clock circuit, increasing the input clock rate to 4MHz. These chips are the SN76489 and the SN76496. They are otherwise also drop-in replacements for your chip, but would require modification to feed them the proper 4MHz clock. I went on a hunt yesterday to see what was out there. I found plenty of SN76496 chips (mostly from Chinese sellers) on eBay, and none of the others anywhere outside of a few of the really hard-core specialty parts distributors (and considering their minimum buy price per line item, you don't want to go there). As noted, it is possible to bypass the external divide-by-8 circuitry on some earlier (TOS) boards to replace your chip with a SN76496. The QI consoles are the last evolution of the motherboards for the TI-99/4A, also referred to the RCP motherboards (Reduced Component Part) in some TI internal documentation. It is relatively easy to tell them from the older boards by a simple visual check. The side port connector has some metal fingers above and below the board that are easily seen without disassembly. Older boards have copper fingers, newer ones have silver (actually, steel) fingers. Even here, there can be a few gotchas, as some QI boards (and rarely, even some older boards) have a different boot GROM that identifies itself as V2.2 on the title screen. That software variant can be a problem, as ROM-only cartridges (pretty much ANY third-party cartridge fits this description, but there are a few exceptions) won't be recognized by the computer. It only looks for cartridges with a GROM in them. I hope this explanation helps some. . .there is a lot of weird stuff to unpack in our fun little machine. 4 Quote Link to comment Share on other sites More sharing options...
Tursi Posted June 10 Share Posted June 10 (edited) 2 hours ago, WCLegere said: New to the TI-99/4A so not sure what u mean by TOS or QI. I'm not new and I've never heard TOS either... or RCP. But then, I suspect about a week ago that I dimension hopped again. Can't remember why that time... Edited June 10 by Tursi 1 Quote Link to comment Share on other sites More sharing options...
+dhe Posted June 11 Share Posted June 11 Sounds like a furture ForTI card would need to be massaged for the chips that are available. 2 Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted June 11 Share Posted June 11 1 hour ago, Tursi said: I'm not new and I've never heard TOS either... or RCP. The last thing I need shoved into my brain is more nomenclature. Quote Link to comment Share on other sites More sharing options...
Tursi Posted June 11 Share Posted June 11 4 hours ago, dhe said: Sounds like a furture ForTI card would need to be massaged for the chips that are available. I think we need to build one on a CPLD instead. Or a PI, since they are being used for everything. 1 1 Quote Link to comment Share on other sites More sharing options...
+chue Posted June 11 Share Posted June 11 49 minutes ago, Tursi said: I think we need to build one on a CPLD instead. Or a PI, since they are being used for everything. You mean like this? 3 Quote Link to comment Share on other sites More sharing options...
+dhe Posted June 11 Share Posted June 11 1 hour ago, Tursi said: I think we need to build one on a CPLD instead. Or a PI, since they are being used for everything. I hope your joking! You know more than the rest of us, of the possibilities opened up to developers with the ForTI card, setup with four good speakers in the correct locations, what could be done. Quote Link to comment Share on other sites More sharing options...
Tursi Posted June 11 Share Posted June 11 1 hour ago, chue said: You mean like this? No need to reply to everything with a link to that thread. No, not like that. An internal replacement for the sound chip. Quote Link to comment Share on other sites More sharing options...
JasonACT Posted June 11 Share Posted June 11 3 hours ago, chue said: You mean like this? No, like this... https://github.com/bluekitchen/btstack/issues/600 2 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted June 11 Share Posted June 11 (edited) Or... Edited June 11 by HOME AUTOMATION ...linked above 2 Quote Link to comment Share on other sites More sharing options...
JasonACT Posted June 11 Share Posted June 11 7 minutes ago, HOME AUTOMATION said: Or... Actually, it's a fair bit annoying listening to "Chariots" in "stereo" when the main channel is only in your left ear. I'm not sure what the author was thinking, but the more options, all the better in my opinion. But just compare the circuit board footprint to a real sound chip "to be real"... The Pico chip, with level shifting, is a no-go, sorry to say. But I'm trying to make it work out. We'll see what comes of it all. 4 1 Quote Link to comment Share on other sites More sharing options...
+chue Posted June 11 Share Posted June 11 9 hours ago, Tursi said: No need to reply to everything with a link to that thread. Overzealous? Yes, I probably am. 3 Quote Link to comment Share on other sites More sharing options...
Gary from OPA Posted June 11 Share Posted June 11 11 hours ago, Tursi said: I think we need to build one on a CPLD instead. Or a PI, since they are being used for everything. So far, this person is working on cpld with a pair of them. 3 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted June 11 Share Posted June 11 2 2 Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted June 11 Share Posted June 11 38 minutes ago, HOME AUTOMATION said: Its 50-year mission... well, almost. 1 3 Quote Link to comment Share on other sites More sharing options...
+FarmerPotato Posted June 16 Share Posted June 16 On 6/11/2024 at 12:11 PM, OLD CS1 said: Its 50-year mission... well, almost. Something is 50 years old in 2025. 1 Quote Link to comment Share on other sites More sharing options...
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