PacMan

They are two different technologies where the FPGA is suited for low volume, high flexibility products and ASIC's fit well in high volume (due its lower price) and more static products. FPGA's can be reprogrammed in the circuit which allows the designer to make multiple spins of his/her logic design and even update the function if a bug is found after the product has been shipped to customers. This also makes the devices more expensive than ASICs. When working with ASIC technology you must design, simulate and fully verify the function of the chip before ordering the devices as the logic functions it performs is fixed on chip and can not be changed at any time. /P

In order to reduce the size of a possible new PCB one could integrate known components such as the 6502, POKEY and all other glue logic into a big FPGA thus reducing space considerably. Replace the DRAM's with an SRAM and you have another reduction. Don't know how feasable it is to implement the graphic chips though although it could certainly be done if someone had the time to look into it. The carts are another story, i'd say that the best thing to do is have an SD connector in the system and put all games on SD/MMC cards. Smack a TFT screen of your choice ontop of everything and you could have a handheld device. Battery time is another issue though but I think that with having replaced many NMOS chips with a CMOS FPGA running on very low speed, it would be something that you could live with. It would certainly be a interesting project to do. /P

Coctail or Coctail Table game ? I know what i want /P

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 What about doing a BIOS mod to clear out the POKEY? The same mod could also shortcut the encryption stuff. 927158[/snapback]

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

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

I had it back in the days, and just recently got one of ebay and now I am playing it with my 13 yo daughter and we are just having a blast with it. Instant fun....... /P

Unfortunately, the video chip in the 5200 doesn't produce RGB, but rather chroma carrier and brightness signals for TV use. The only way to get RGB is to decode them like a TV does. -Bry 920852[/snapback] And that wouldn't necesserily produce a higher quality picture as it means more processing on the signals compared to the S-Video mods. /P

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

I'm just thinking out loud here. If I connect A15 through an inverter to CE* of a 28F010 and tie OE* through another inverter to the R/W* signal of a 6502 and then execute 256 NOP's from the FLASH, would it work ?? The A15 signal will stay high through all these 256 opcodes thus eliminating any pulses to the CE* pin !? This is interesting, i will have to look more into this. /P

How is the rest of your board configured ? Do you have OE* tied low at the same time, or is it tied to an enable signal (like A15* or similar) ? If it's connected to an inverted version of R/W* you will have data bus conflicts when the CPU is trying to read from outside the FLASH area. This will cause the unit to crash. If you have it connected to a chip select signal (such as A15* or similar) it should really work, in that case i haven't got a clue A recent schematic and a description of your configuration would help. I have a contact with a chinese company that manufactures excellent PCB boards with any soldermask color that you want. Good pricing as well. Small volumes such as 200 pcs is no problemos with them either. let me know if you're interested. /Pontus

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

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. 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. 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

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

Thank you everyone that have PM'd me, it was exciting to see the response of the XBoarD. Unfortunatly i only had 4 boards to go this time so a lot of you didn't get a board this time. Currently I have 9 more people that are interested in the board and I will be making a new batch of boards for you guys. If there is anyone else that wants to have their own XBoarD let me know in a week or two so i don't order in to few PCB's. I estimate to have these boards ready to ship in about 5 weeks and they will cost USD$39.95 (Nutty price I know, but I wanted to have $40 without actually having to say $40). That includes the RAM but no POKEY. The pokeys are USD$5 each but they can easily be ordered from Best Electronics which is also where I get them (for the same price). I know for instance that Schmutzpuppe's Frogger will support the XBoarD and I sure hope that there will be more games in the future. /P

Is that right? EDIT: I'm talking about where the asterisks are. 914111[/snapback] Oops, definitly not so, it should look like this. XCTRL Bit Description +-------------------------------+ | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +-------------------------------+ | | | | | | | | | | | | | | | +-- Bank select bit 0 \ | | | | | | +------ Bank select bit 1 | Totally 128 KByte in 16 KByte banks | | | | | +---------- Bank select bit 3 / | | | | +-------------- Enable memory bit (1 = Memory enabled, 0 after power on) | | | +------------------ Enable POKEY bit** (1 = POKEY enabled, 0 after power on) | | | NA NA NA = Not Available or Not Used * = Can be mounted piggy back on the first POKEY. Description how to do this will come when i have tried it out. ** This bit controls both POKEY chip select signals. Thanks for pointing that out. Frogger will support Xboard. I don't know yet what will happen without Xboard it depens a bit if Bruce manage to make a pokey version of his prototype board because I would really like to avoid tia sound. Cybergoth's frogger music is quite cool for tia but pokey can do better. On the other hand I am not sure about this whole cartridge production stuff maybe there will never be a fogger cart only the binary. It's fairly easy to detect if a POKEY is present at a certain adress so it should not be problem to make your algorithms detect if a POKEY is available at either XBoarD adresses or at $4000. /P

The XBoarD is completely disabled after startup which means that it will have no impact on the system. So plugging a standard POKEY Cart will work just fine. If Schmutzpuppe adds POKEY support to Frogger he could implement a small function that would evalute where a pokey is available. This would make it possible to run Frogger on Carts with POKEY's or from simple ROM Carts on systems equiped with the XBoarD. Again, the XBoarD is completely disabled on startup so normal RAM carts will also work as expected. A technical note..... When I say completely disabled i mean that the POKEY's and the SRAM are disabled. The XCTRL register is not disabled, it is still enabled at $0470-$047F allowing you to configure your system at any time. /P

Last proto board is gone now, thank you everyone for your interest. If anyone else is interested in getting a board let me know and i will see what the possibilities are of making some more. /P

Definitly so, I thought about the pass through idea but was discouraged by the mechanical design. If someone does make a pass through adapter it would be nice to have the POKEY's mapped to the same place ($0450/$0460). Cacthing and remapping accesses to a cart would be possible but not practical as you mentioned. 128K is probably overkill but 16K is a little on the low side, depending on what you want to do of course I just had these chips available (a lot of 'em) and they made for a nice design. Well, I finally settled for the basic design which maps the POKEY chip selects to $0450 and $0460, whith the XBoarD control register at $0470. This means that the mapping for the device now looks like this. Description: Start: End: Size: POKEY1 $0450 $045F 16 bytes POKEY2* $0460 $046F 16 bytes XCTRL $0470 $047F 1 byte RAM $4000 $7FFF 16384 bytes XCTRL Bit Description +-------------------------------+ | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +-------------------------------+ | | | | | | | | | | | | | | | +-- Bank select bit 0 \ | | | | | | +------ Bank select bit 1 | Totally 128 KByte in 16 KByte banks | | | | | +---------- Bank select bit 3 / | | | | +-------------- Enable memory bit** (1 = Memory enabled, 0 after power on) | | | +------------------ Enable POKEY bit (1 = POKEY enabled, 0 after power on) | | | NA NA NA = Not Available or Not Used * = Can be mounted piggy back on the first POKEY. Description how to do this will come when i have tried it out. ** This bit controls both POKEY chip select signals. An assembly instruction with instructions on how to connect the audio signal will be available beginning of next week. 1 board left now, I have charged USD $35 for these plus shipping ($5.00 ww) and if you want a pokey chip to go with it it's another extra $5.00. Just send me a PM if you're interested. /P

You are absolutely right, that is the way to do it. No problems it's just fun to have found a bunch of crazy people with the same interest as my self It could probably be done this way but you would have to have a rather long flat cable in order to get up from underneath the board. This would affect the impedance on the buses of the system and you would start to see over and undershoot on the signals which is never nice. It might work but it might not and i would not recommend this attempt. It is better to desolder the MARIA and insert the XBoarD in the correct place. As Bruce Tomlin mentioned you could use two standard 24 dip sockets on the 7800 motherboard. It is not easy to desolder a DIP device if you don't have the proper tools. If you are unexperienced you could contact your local TV repair shop (if there are any left), they should have the proper tools for this. I would really recommend this way instead of doing it yourself, we don't want to destroy our precious do we ??? I could probably do it for you but the cost of shipping the 7800 back and forth to Sweden would probably kill anyones budget /P

One idea that i was playing with is that when RAM is disabled but the POKEY is enabled it would be mapped to $4000-$7FFF which looks more like the standard mapping. Problem is that a normal Cart would still not see it as the XBoarD is completely disabled after startup. Gotta think some more about that /P

Bakasama -> Although i don't have a CC2 i am reasonably certain that the XBoarD does not conflict with it on startup. The XBoarD is completely disabled after power up and needs to be configured to enable the functions (RAM/POKEY). Having said this I have no idea if the CC2 makes any use of addresses between $0450 - $047F which is where the XBoarD is configure. Anyone ? Bruce Tomlin -> Yes this is a PAL 7800 and the XBoarD needs a clearance of 19mm from the legs of the MARIA chip to fit. I figured that the NTSC versions would have had their MARIA's soldered due to the higher volumes it was produced in. The MARIA is actually a 48-pin device and it is not much harder to desolder than a standard 40-pin device, providing you are using a proper tool. Otherwise it is darn right impossible. As i mentioned, the mapping is done in a PLD and could be anyting. If you want the POKEY to be in the area between $4000-$7FFF this is also possible. One could even map the POKEY at $4000-$7FFF and place RAM from $4010-$7FFF if desired. As the picture below shows the RAM is hidden under the MARIA and the PLD and latch is found under the POKEY. In the tests that I have done i have the RAM mapped from $4000 up to $7FFF. The configuration latch is located at $0470-$047F and is write only. It uses 5-bits to configure the board. Bits 0 - 2 selects the RAM bank, Bit 3 enables the RAM and bit 4 enables the POKEY's. I just wish i had used bit 5 to, this way i could have made a selection for where to map the POKEY's. Anyway, thank you fo your interest. Regards /P

Hi There, If anyone is interested i have a few prototype cards for an internal 128KByte and POKEY expansion for the 7800 for sale. The expansion (XBoarD) card fits into the socket of the MARIA which means you have to take out the MARIA chip and insert it into the new socket on the XBoarD. Both the POKEY and RAM is disabled after startup, so you need to enable them in your own code. This means that the XBoarD is normally not available for existing games. The mapping is totally non compatible with pretty much everything. There is a bank select latch located at $0470 and the POKEY is located at $0450 (There's also a chip select output ($0460) on the PLD which alows you to simply piggy back a second POKEY). Since the PLD is reconfigurable I could map the POKEY (or the RAM for that matter) to pretty much anything if you wanted to. However since the PLD is soldered under the POKEY this needs to be configured before delivery. I designed and built this unit purely for my own purposes but it turned out pretty good and i have a few proto's that i don't need. I will sell these for the cost of the components (which wasn't very low though ) Here are two images of the board: The red cable going to the system is the audio cable feeding into the EXTAUD input on the cartridge connector. And here's a picture of the unit mounted in one of my 7800's Anyone interested or have questions ? /P

Providing that your TV supports NTSC there are no issues as to the console itself. It works perfectly for me. The powersupply needs to be thrown out the window though I bought a new supply (Needs to be rated at at least 1 [email protected]) with a 2.5mm power plug (+ in the middle). This is for the 4port version, i do not know what the 2port power plug looks like (Anyone ?). /P

That looks promising. Does you CAD system has a poly fill feature ? If so, use it to create a ground plane on the solder side of the board. You should also try to cram in a decoupling cap for the PLD, those guys are real trouble makers, especially the new fast types. Consider using surface mounted 0.1uF, 0805 caps for decoupling, they are easier to mount and easier to place. If you only have a really big solder iron, you might consider using size 1206. The best place to put the caps are on the solder side of the board right between the power pins. Good Luck, /P