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7800 XM update


Curt Vendel

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That's a good question Trebor. Hopefully we can get some info on how these potential conflicts are going to be handled.

 

To be on the safe side with DK PK, I write to the XM control register to disable it's onboard POKEY. I'd recommend that for any programmer releasing a cart using CPUWIZ's POKEY board.

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That's a good question Trebor. Hopefully we can get some info on how these potential conflicts are going to be handled.

 

To be on the safe side with DK PK, I write to the XM control register to disable it's onboard POKEY. I'd recommend that for any programmer releasing a cart using CPUWIZ's POKEY board.

 

Glad DK PK is already covered. :)

 

There's concern with other POKEY chip included homebrews too that do not have the code which disables the XM control register, due to the code or/and device not being known at the time...such as Beef Drop (Not V.E.). Indeed, hopefully we can get some info on how these potential conflicts are going to be/being handled.

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Beef drop has the pokey at $4000 like ball blazer. It always writes to both pokeys address but it disables an xboard pokey if it detects both.

Beef Drop works on CPUWIZ's POKEY Developer Cart, which was a surprise to him, so you got it right.

The Dev Cart may appear as an xboard, (not sure, you would have to ask him).

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Beef Drop works on CPUWIZ's POKEY Developer Cart, which was a surprise to him, so you got it right.

The Dev Cart may appear as an xboard, (not sure, you would have to ask him).

 

Yes, there is no way in hell my DevCart can deal with a POKEY at $4000, it's probably the other way around. You can address the POKEY on the DevCart or VersaBoard in slots between $0400-$047F and $0500-$057F. So, if you test for any of those 16 regions, you will get a success return.

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Beef drop has the pokey at $4000 like ball blazer. It always writes to both pokeys address but it disables an xboard pokey if it detects both.

 

Thanks for this Ken, it's very much appreciated. Just so my layman self understands this clearly... :)

 

Beef Drop writes to both $4000 & $0450 for POKEY, but will disable/stop the $0450 writes (or is it more turns off the POKEY chip at that address), if it detects POKEY at $4000?

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It always writes to 4000 and 450 if it is in pokey mode. It won't do the xboard enable sequence if a pokey at 4000 is detected. This would in theory keep both from playing. If no pokeys are detected it won't write to either address

 

Awesome...Thanks for the clarification and explanation, Ken!

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It won't do the xboard enable sequence if a pokey at 4000 is detected.

 

Hi, maybe I'm missing something here but if I run Beef Drop in MESS, it first writes a long series of 0x00 to the XCTRL reg, which is fine, but right on the title screen it writes 0x10 to XCTRL and this (to my knowledge) is enough to enable the POKEY at 0x0450 later on...

Could you clarify a bit more what happens on the real hardware, so that I can make the emulation more accurate? thanks in advance!

 

EDIT: ok, silly me... the MESS code I was using was not allowing to read POKEY registers at 0x4000, which I guess it was what you were using to test the presence of the POKEY mapped there. allowing the registers to be read at 4000 fixes the problem and 0x10 is not written anymore to XCTRL :)

Edited by etabeta
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It always writes to 4000 and 450 if it is in pokey mode. It won't do the xboard enable sequence if a pokey at 4000 is detected. This would in theory keep both from playing. If no pokeys are detected it won't write to either address

 

I have to ask…did you add POKEY audio to your 7800 Centipede - TB Edition? And did AtariAge ever generally release that on cartridge or was it always a custom order?

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Does anyone know if there is such a thing as an Atari "Y" Adaper so someone could plug in a Joystick and a Trackball into the same port at the same time?

 

http://www.ebay.com/itm/TI-99-4A-Atari-joystick-adapter-cable-/221542518836

 

 

I would also imagine that any serial DB9 Y-splitter in conjunction with whatever gender changing adapter(s) and extension cable(s) as necessary would work fine as well. However, I could be wrong - Never tested it personally.

http://www.ebay.com/itm/DB9-Y-Adapter-Cable-DB9-M-2-DB9-F-NIP-NOS-/121420874776

 

Or perhaps even this with the aforementioned scenario as well:

http://www.monoprice.com/Product?c_id=104&cp_id=10404&cs_id=1040403&p_id=4640&seq=1&format=2

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I'm pretty sure that will only work on a TI. I think the joystick pinout is different on the TI, and that swaps some wires to make it Atari compatible. I think the TI joystick (not Atari compatible) came in a set of 2, wired together to one DB9. So that TI adapter is Atari on the 2 ends of the Y and TI on the single end. At least I think I remember such a discussion. Check the pinouts before you buy.

 

I, too, was looking for a Y-cable and couldn't find one until recently. I never tested any of this stuff, but I wanted a Suncom Starfighter joystick anyway, and this came with one:

 

eBay Auction -- Item Number: 2715628779861?ff3=2&pub=5574883395&toolid=10001&campid=5336500554&customid=&item=271562877986&mpt=[CACHEBUSTER]

 

The box was trashed but it looked like original wire ties on the cables. I'm assuming that's an Atari Y cable I got there, but who knows? Atari Y-cables used to even be sold at B&C and on Ebay years ago but not common now. The DB9 serial cables don't usually fit into the Atari port because they're too big on the outside, if memory serves.

 

Edit: Now that I looked at my auction picture and how large the single end of the cable is, I'm starting to think it may be an adapter too, possibly for TI. I suppose I'll have to try it when I get more time.

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Thanks for the info wood_jl. Looks like there was yet another recent discussion with a couple of brands listed here:

 

http://atariage.com/forums/topic/103902-9-pin-y-adapter/

 

Also, some good info here:

 

http://atariage.com/forums/topic/103902-9-pin-y-adapter/

 

Probably best to take this to the first link or start a new thread...We're just a tad off topic from "XM Status Update"...LOL.

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http://www.ebay.com/itm/TI-99-4A-Atari-joystick-adapter-cable-/221542518836

 

 

I would also imagine that any serial DB9 Y-splitter in conjunction with whatever gender changing adapter(s) and extension cable(s) as necessary would work fine as well. However, I could be wrong - Never tested it personally.

http://www.ebay.com/itm/DB9-Y-Adapter-Cable-DB9-M-2-DB9-F-NIP-NOS-/121420874776

 

Or perhaps even this with the aforementioned scenario as well:

http://www.monoprice.com/Product?c_id=104&cp_id=10404&cs_id=1040403&p_id=4640&seq=1&format=2

 

Thnak you for the info, sorry for getting OT.

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Just wondering how things went at CGE respecting the XM 'demoing/testing'; hoping (relatively) well.

 

Any pics or/and videos would be most appreciated. :)

 

If you're on Facebook, Curt posted several short video clips late yesterday afternoon in the Atari Museum group. The XM played POKEY sound just great from a BEEF DROP VE cart and DONKEY KONG XM, and also seemed to play nice with a couple carts with on-board POKEY chips.

Edited by DrVenkman
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I saw, held, and handled the Atari 7800 XM just yesterday before Curt packed up and headed back to NY. It was not hooked up to a 7800, but just there to be showcased.

 

It is a beautiful piece of hardware. The plastic casing is perfectly true to the original 7800 shell. It carries a nice weight, and feels like a solid piece of classic gaming hardware. The aluminum plating is very nice, done by the same company that did the originals if I heard correctly.

 

That is all!

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