Any known audio issues on a Jaguar with Stubulator (using a retail cart)?

[BigFatGingerCat]

Hi,

 

I've recently dug out my old Jaguar devkit from the loft (NTSC console with Stubulator ROM, & 2MB Alpine board), and have been trying to test if it all still works. I was originally shipped this kit back in the mid 90s in order to do some audio code work for a client, all fully Atari-licensed, who never asked for it back and it's been in the loft ever since!

 

After a lot of digging, I managed to verify that the Alpine board seems to work fine - I was able to use the available Linux tools, mainly rdbjag, to perform several operations with the kit, send over a bunch of ROM images, etc. The Falcon which came with the kit found another home many years ago, to make a bit of room in the loft - wish I'd hung on to that now though.

 

What I'm curious about though, is running a regular retail cart on the Stubulator-modified console. I tried a couple of carts owned by a friend, and they both seem to work (if I power up the Jag whilst holding the B button on the controller, otherwise it boots to a blue screen with a development system message) but the audio output is highly distorted. Running the same games by uploading their images to the Alpine board, the audio is fine.

 

I really don't know very much about this system, so was wondering if anyone here might know what could cause this? I don't think the audio output is broken on the console, otherwise running the games via the Alpine would surely have the same problem. The only thing I could think of was that perhaps there's something electrical which isn't right when the Alpine isn't present (perhaps grounding or something?), since there's a small ribbon cable coming out of the console's case which plugs into the Alpine, and this remains unconnected of course when using a retail cart.

 

Also, I'm not sure if this is normal on these developer Jaguars but the main red power switch appears to be totally unconnected on mine - the console simply powers up when connected to the mains, and the switch does nothing. But this is how it came to me from Atari, via the client

 

Many thanks in advance for any replies!

[Zerosquare]

Could you record the distorted audio? (by plugging the audio output to the input of your sound card if you can ; but if you can't do that, recording the audio thru a microphone would be better than nothing)

 

It could be an electrical problem indeed, but it could also be something software-related.

[Chilly Willy]

I'd guess the development rom init that occurs before it checks for the bypass button (B) is causing an issue with the cart's init of the system. Or maybe the way they start the cart on bypass skips part of some init the cart boot code runs, which leaves the console in a state it can't handle. Just some guesses...

[TXG/MNX]

The stub does something different while initializing the console.

 

There are 2 versions of stub's the '93 and '94 version, which version do you use and what game, I can check if I can reproduce the same issue here on my dev jag.

 

Also not a SKUNK board doesn't work on a developers jag aswell... only on retail consoles.

[TXG/MNX]

Can you tell me what game was in development with that devkit ? Do you still got stuff from that era like documents, sources or binairies ? Would be nice to see what you dusted off...

[BigFatGingerCat]

The stub does something different while initializing the console.

 

There are 2 versions of stub's the '93 and '94 version, which version do you use and what game, I can check if I can reproduce the same issue here on my dev jag.

 

Also not a SKUNK board doesn't work on a developers jag aswell... only on retail consoles.

 

The copyright message on-screen says '93, so I'm guessing that's what you mean. The retail carts I tried were Tempest 2000 and CyberMorph. Both had distorted audio, and in fact when booting the console via the B-button bypass, there is a Jaguar logo displayed on-screen with an accompanying sound effect which is also distorted. Although in all honesty I don't know if that logo is part of the console's bootup or something that's added to each cart, so is effectively part of the cart's bootup.

[BigFatGingerCat]

Can you tell me what game was in development with that devkit ? Do you still got stuff from that era like documents, sources or binairies ? Would be nice to see what you dusted off...

 

I was doing some audio code for Anco's Kick Off series. I don't think it ever got finished/released though. From memory, it sort of fizzled out whilst I was in the middle of working on the audio, then I didn't do anything more with Anco. Don't have any sources or binaries from that project I'm afraid. Although I do have printed Atari dev manuals for the Jaguar, with 'Anco' printed in huge letters over every page...

[Zerosquare]

The copyright message on-screen says '93, so I'm guessing that's what you mean. The retail carts I tried were Tempest 2000 and CyberMorph. Both had distorted audio, and in fact when booting the console via the B-button bypass, there is a Jaguar logo displayed on-screen with an accompanying sound effect which is also distorted. Although in all honesty I don't know if that logo is part of the console's bootup or something that's added to each cart, so is effectively part of the cart's bootup.

The Jaguar logo and sound effect are in the Jaguar's internal ROM, not in the cartridges. So it looks like the Stubulator code does something that causes the audio not to work normally. It's a bit strange since there are not that many audio-related registers, and games are supposed to initialize them themselves anyways, but you never know.

[BigFatGingerCat]

Yep, it's why I'm wondering if it's some kind of minor electrical glitch when the Alpine board isn't present and the ribbon cable hanging out of the back of the Jag is just left dangling there. I simply know nothing about the insides of these things so it's just guessing...!

[sh3-rg]

All three of my stubulator jaguars have been the 94 flavour. I don't recall any of these issues with it. Maybe the 93 version does that? Robert would probably be able to test.

[JagChris]

 

I do have printed Atari dev manuals for the Jaguar, with 'Anco' printed in huge letters over every page...

 

What are the dates on these manuals if I may ask? The same? Newer?

[BigFatGingerCat]

 

What are the dates on these manuals if I may ask? The same? Newer?

 

Can't recall off the top of my head I'm afraid, the manuals are still in another box in the loft.

[LinkoVitch]

Is it not that holding the buttons boots in either 16bit mode or 32bit mode (cart bus width) with stub jags? Long shot since the games run but perhaps that could be the cause?

 

Also in the manual it does say (my version anyway) that you should have a resistor between 2 of the pins on the ribbon cable if the unit is used without the Alpine. Another long shot, but hey, this is the Jaguar

 

HTH

[+rdemming]

Is it not that holding the buttons boots in either 16bit mode or 32bit mode (cart bus width) with stub jags? Long shot since the games run but perhaps that could be the cause?

 

Also in the manual it does say (my version anyway) that you should have a resistor between 2 of the pins on the ribbon cable if the unit is used without the Alpine. Another long shot, but hey, this is the Jaguar

 

HTH

 

According to the docs, a 1K resistor must be indeed be put between the ribbon cable pins 4 & 5 when not used with an Alpine. But I've never had problems with my ribbon cable Jaguar without the resistor connected. I've indeed both the 93 (blue) and 94 (green) stubulator but never had any issues with sound.

 

With the stubulator, turning on while holding the "B" button starts a regular cart. Holding the "C" buton starts the CD-BIOS (if attached) which is a 8-bit wide "cart" (only the green stubulator, CD does not work with the blue stubulator).