PacMan Posted August 27, 2005 Author Share Posted August 27, 2005 Hi All, I have been asked by several people if I could put the XBoarD functionality into a pass thru cart instead of having it internal to the 7800, thus minimizing the effort of installing it. I have made a brief analysis of this and i think that it is clearly possible. I recently purchased a few cart boxes from Videogam Wiz to put my own games in. I have toyed around with one of them and came up with a mechanical solution close to Curt Vendel's HSC. Now, i can easily put together a few boxes for me and my friends, but that wouldn't benifit the 7800 community as a whole. So if I were to produce a small batch of these would anyone be interested ? Please note that I am not looking for any commitment just now. I am just curious to see if there is any interest in such a box. The Box would have the following features: * Sockets for 2 POKEY's (Possibly with stereo phono jack output) * Possibly an analog mixer for the pokeys to map the stereo sound. * 128K SRAM (Possibly battery backed) * Let mew know of your suggestions for features * Of course compatible with the exsisting XBoarD's Lets keep the discussion open in this forum. /P Quote Link to comment Share on other sites More sharing options...
Bruce Tomlin Posted August 27, 2005 Share Posted August 27, 2005 Before you go all ga-ga about stereo (which I think is overrated in Atari consoles anyhow), don't forget that the cartridge slot only has one audio input line. And it's possible (though currently I don't think it's been done) that a game could use TIA sound at the same time. I was thinking that it might be nice if an inch or so could be sawed off of the end of a cartridge to make it shorter. Of course this means that the board would have to be wide at the bottom, which should be enough room for one POKEY chip. Oh yeah, that's another problem... are you sure you can even fit two POKEY chips and a cartridge slot in that space? Cartridge shells aren't very friendly to socketed chips in the first place, and I think that it would be rather tricky to fit a socketed POKEY on the back of the board. The CC2 had to have the screw post broken to fit its POKEY in. Quote Link to comment Share on other sites More sharing options...
DracIsBack Posted August 27, 2005 Share Posted August 27, 2005 Before you go all ga-ga about stereo (which I think is overrated in Atari consoles anyhow), don't forget that the cartridge slot only has one audio input line. And it's possible (though currently I don't think it's been done) that a game could use TIA sound at the same time. I think COMMANDO is the only one that does this. If you play the game on a Cuttle Cart without a POKEY, you'll hear the sound effects. If you add a POKEY, the music gets added too. Probably has to do with why Commando sounds better on the 7800 than the XE ... they use the TIA and the POKEY for sound and music. Quote Link to comment Share on other sites More sharing options...
PacMan Posted August 27, 2005 Author Share Posted August 27, 2005 Before you go all ga-ga about stereo (which I think is overrated in Atari consoles anyhow), don't forget that the cartridge slot only has one audio input line. And it's possible (though currently I don't think it's been done) that a game could use TIA sound at the same time. Stereo output may be overkill but I remember installing this for my Atari800 in the 80's and making some really nifty effects with it And you are absolutely right the TIA can be used at the same time the pokey is used. If you ask me it is a waist to leave the TIA out since it is a resource and resources are expensive. I was thinking that it might be nice if an inch or so could be sawed off of the end of a cartridge to make it shorter. Of course this means that the board would have to be wide at the bottom, which should be enough room for one POKEY chip. Yepp, that would be nice, however I have no intention of starting a production of plastic boxes. It is way to expensive and not my field of expertice. So if I were to do something like this it would be in a prefabricated case, like the one from Videogame Wiz. You could, as you say, saw a piece of the case of. But that will have a negative impact on stability of the unit. My idea is to have the top end of the PCB fixed between the two case halves. This will make it stable enough for most users. Oh yeah, that's another problem... are you sure you can even fit two POKEY chips and a cartridge slot in that space? Cartridge shells aren't very friendly to socketed chips in the first place, and I think that it would be rather tricky to fit a socketed POKEY on the back of the board. The CC2 had to have the screw post broken to fit its POKEY in. Most definitly so, two pokeys are no problem in the boxes i have. All other devices on the board will be surface mounted and can be placed below the pokeys so it shouldn't be a problem. What i can see can be a problem is to fit a battery for a battery backed SRAM, but i will look into that, .... if anyone is interested of course. /P Quote Link to comment Share on other sites More sharing options...
shadow460 Posted August 28, 2005 Share Posted August 28, 2005 I think I'm more partial to an internal upgrade. An extra cart is that much more I can lose. With the internal mod, you never even have to worry about it. XboarD kicks in when it is needed, and sits by quietly when it is not. Quote Link to comment Share on other sites More sharing options...
Bakasama Posted August 29, 2005 Share Posted August 29, 2005 I think I'm more partial to an internal upgrade. An extra cart is that much more I can lose.With the internal mod, you never even have to worry about it. XboarD kicks in when it is needed, and sits by quietly when it is not. 920016[/snapback] I think the point is that you don't have to take out the pass thu cart unless your cleaning the 7800. Plus there are models of 7800s that you have to use a solder iron to install that upgrade. Not everyone has a soldering iron or knows how to use it correctly. Quote Link to comment Share on other sites More sharing options...
PacMan Posted August 31, 2005 Author Share Posted August 31, 2005 One quirk found with the XBoard. If you are continously executing operations on the RIOT, the clock (phi2) to the pokey will be slowed down and the output frequency changed. This is not a problem if you only check the joystick every frame but if you need to do intensive manipulation of the RIOT you need may need to take this into consideration. The same would happen if you were to execute code from the RAM in the RIOT. /P Quote Link to comment Share on other sites More sharing options...
Bruce Tomlin Posted August 31, 2005 Share Posted August 31, 2005 Wouldn't that be true with any POKEY usage on the 7800? Not that I've heard of it before, because I haven't. RIOT RAM usage is discouraged anyhow, and I don't think you normally need to access the I/O ports more than once per frame unless you're trying to read the paddle or something like that. Quote Link to comment Share on other sites More sharing options...
PacMan Posted September 1, 2005 Author Share Posted September 1, 2005 Wouldn't that be true with any POKEY usage on the 7800? Not that I've heard of it before, because I haven't. RIOT RAM usage is discouraged anyhow, and I don't think you normally need to access the I/O ports more than once per frame unless you're trying to read the paddle or something like that. 922701[/snapback] Correct, you also must use phi2 as a clock source as it is used for controlling the bus cycles internally to the chip as well. So no getting around this for the 7800. I did some experimenting yesterday evening and as long as you only have normal usage of the RIOT such as reading the joystick values once or twice every frame it is not noticable at all. I noticed the phenomena when using devOS as it was looping very fast to check the console buttons, thus reading from the RIOT. A single wait for a v_Blank cured this and also gave a more stable button detection. /P Quote Link to comment Share on other sites More sharing options...
PacMan Posted September 5, 2005 Author Share Posted September 5, 2005 Just a short notice, It is important to reset the pokey chips before starting to use them. The pokey does not have a hardware reset input and needs to be reset by software before it can be used. This is done simply by writing a zero to all 16 registers in the device. Start from the first register and continue upwards. Here's a short snippet that gives you one way of doing it. lda #XENABLEPOKEY ; Enable the XBoarD pokeys ora XCTRL_SHDW ; Update shadow jsr SetXCtrl ; Set the values lda #$00 tax ST2: sta XPOKEYBASE1,X ; Clear Pokey1 sta XPOKEYBASE2,X ; Clear Pokey2 inx cpx #$10 bne ST2 lda #3 sta SKCTL + XPOKEYBASE1 ; Start it up /Pontus Quote Link to comment Share on other sites More sharing options...
cschell Posted September 5, 2005 Share Posted September 5, 2005 Isn't the lack of reset a potential problem with your internal POKEY boards? What if they came up in a state where they were playing a sound? If one was playing a game that wasn't aware of your POKEYs the sound would never get shut off. Chad Quote Link to comment Share on other sites More sharing options...
PacMan Posted September 6, 2005 Author Share Posted September 6, 2005 This issue has been identified and investigated. I did testing on 10 different pokeys, shutting the system on and off 10 times but none of the tested devices started with any sound on. Having said that, it still remains and issue. An issue that have been solved in rev.B of the board using a digitally controlled analog switch. The switch completely disconnects the pokey audio output. The switch is actuated by the enable signal from the CTRL register of the board. /P Isn't the lack of reset a potential problem with your internal POKEY boards? What if they came up in a state where they were playing a sound? If one was playing a game that wasn't aware of your POKEYs the sound would never get shut off. Chad 925662[/snapback] Quote Link to comment Share on other sites More sharing options...
cschell Posted September 7, 2005 Share Posted September 7, 2005 The switch sounds like a good way to go. I have had cases where the POKEY played sound on startup. It was most common after the POKEY had been playing sound before shutting off the system and restarting it. Chad Quote Link to comment Share on other sites More sharing options...
Shaggy the Atarian Posted September 7, 2005 Share Posted September 7, 2005 Before you go all ga-ga about stereo (which I think is overrated in Atari consoles anyhow), don't forget that the cartridge slot only has one audio input line. And it's possible (though currently I don't think it's been done) that a game could use TIA sound at the same time. I was thinking that it might be nice if an inch or so could be sawed off of the end of a cartridge to make it shorter. Of course this means that the board would have to be wide at the bottom, which should be enough room for one POKEY chip. Oh yeah, that's another problem... are you sure you can even fit two POKEY chips and a cartridge slot in that space? Cartridge shells aren't very friendly to socketed chips in the first place, and I think that it would be rather tricky to fit a socketed POKEY on the back of the board. The CC2 had to have the screw post broken to fit its POKEY in. 919615[/snapback] As long as software would come along to take full advantage of it (which I'm sure it will), I'd get one. Quote Link to comment Share on other sites More sharing options...
supercat Posted September 8, 2005 Share Posted September 8, 2005 I did testing on 10 different pokeys, shutting the system on and off 10 times but none of the tested devices started with any sound on. Having said that, it still remains and issue. What about doing a BIOS mod to clear out the POKEY? The same mod could also shortcut the encryption stuff. Quote Link to comment Share on other sites More sharing options...
PacMan Posted September 8, 2005 Author Share Posted September 8, 2005 That requires that you exchange the BIOS chip as well, meaning more desoldering for the NTSC consoles. The analog switch solves the issue without adding to much to the total complexity of the board. I am sort of partial to the internal expansion board as it gives me more options on how to solve the sound generation. I am leaning towards a solution with stereo outputs on the back of the console, with the TIA sound centered in both channels. In order to achieve a sound which is listenable there is also a pan control for the pokey outputs allowing you to move the sound from one channel to the other. This would be impossible to do in a pass thru cartridge. /Pontus I did testing on 10 different pokeys, shutting the system on and off 10 times but none of the tested devices started with any sound on. Having said that, it still remains and issue. What about doing a BIOS mod to clear out the POKEY? The same mod could also shortcut the encryption stuff. 927158[/snapback] Quote Link to comment Share on other sites More sharing options...
shadow460 Posted December 25, 2005 Share Posted December 25, 2005 I hope the xboard project is still humming along smoothly. If there are any more that have been made, I want to buy one. (I'll cross the installation bridge when I get to it...) Quote Link to comment Share on other sites More sharing options...
PacMan Posted December 26, 2005 Author Share Posted December 26, 2005 It most definitly does so. Currently I have 30 PCB's in my hand, and will be starting to assemble and testing these during the christmas holiday. For those of you with the MARIA chip soldered to the mother board I will be offering to desolder the MARIA chip, replace it with a socket that can hold the XBoard and finally test the unit. You need to ship the A7800 motherboard to me and pay for the return postage. More information on the final board and the upgrade service will follow as soon as I have the time to finalize it. /PacMan I hope the xboard project is still humming along smoothly.If there are any more that have been made, I want to buy one. (I'll cross the installation bridge when I get to it...) 989132[/snapback] Quote Link to comment Share on other sites More sharing options...
shadow460 Posted December 26, 2005 Share Posted December 26, 2005 Nice work! Quote Link to comment Share on other sites More sharing options...
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