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About ZackAttack

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  1. I've been toying around with building my own PCB for the 2600 and I've noticed that the price difference between ENIG gold fingers and hardened gold is quite a bit. Especially in low volumes. Does anyone know if there are existing cart PCBs that have used ENIG for the gold fingers plating and how well they have held up? My concern is that ENIG might seem to work fine for the first couple of years, but will eventually have corrosion or wear problems that only show up after years of service.
  2. I just added a permissive license to the strong arm repo. I think that's necessary since most will want to modify something and include it with their games. Unocart firmware has a license on github as well: https://github.com/robinhedwards/UnoCart-2600/blob/master/LICENSE It's worth noting that although the unocart is the only hardware that currently supports this framework, the plan has always been to have a stripped down cheaper cart for publishing games. In that scenario the unocart licensing wouldn't apply since strong arm can bootstrapped directly without going through the uno firmware.
  3. It's been a while since I've played with that, but if I recall correctly. There were two types of failures with the early bus stuffing attempts. The first type was when the cart failed to stuff its value onto the bus. The other type was timing related. Some systems, mine in particular, have some unusual address bus activity in the transition time between valid bus signals. The timings are compliant with the 6502 datasheet as far as I can tell. The problem is that the carts don't have access to any clock signals and have to poll the address bus to determine which rom location to emulate or which address location its stuffing a value into. If a transient value is identified as the next location, the cart will produce the wrong value and probably spend too much time doing so to catch the actual value that follows. I completely bypass this problem in the strong-arm framework by keeping track of where 6502 will be reading next, precalculating the corresponding value, polling for the specific address value, and posting the data onto the bus as soon as the expected address is present on the bus. This has the bonus side effect of leaving more time to do useful work on the ARM core between 6502 bus servicing.
  4. Have you ever tried out this other bus stuffing implementation demo on that problematic junior?
  5. If you look at the unocart firmware you'll find that it's already writing to the flash memory for the larger schemes like 3E when the bin is too big to fit in RAM. So just use that as a template to add flash memory writing support to your own arm project. I think it would be good if we reserved sector 3 for saved game data and defined a simple structure to allow multiple games to share it. It would also be nice to add import/export functionality to the firmware so you could backup to SD or share your games saves. Though if you only care about a stand alone cart, you could use whatever sector you want, any way you want.
  6. Assuming you are referring to the values that are at those locations after power on reset. The firmware would need to be enhanced to restore the original RAM values before handing execution over to the ace file. The current firmware overwrites all the TIA RAM on startup and discards the original values. Might be worth posting something in the official firmware thread.
  7. vcsWrite3() is a WIP implementation of bus stuffing. I plan to implement error detection and correction to account for some systems that have been problematic in the past. When it's done there will be a routine provided that does the error detection and provides the masks and values needed for A, X, and Y. Then vcsSetMasks() would be called during initialization and vcsLd*() would be called for A, X, and Y prior to using vcsWrite3(). Write3() will select STA, STX, STY, or SAX depending on the value being stuffed so that only 6 of the 8 bits need to be overridden by the ARM chip. Which 2 bits aren't stuffed will depend on the results of the error detection.
  8. The ACE file format is used to update the unocart firmware. ACE compatibility is part of the required testing for unocart firmware releases. It's safe to assume that ACE will continue to be supported on unocart. The c/c++ framework itself is pretty self contained and could even be used with other hardware solutions as long as the microcontroller has enough resources. Stella is the main thing you need to take into consideration. For development purposes I have a fork of the stella source that can run ACE/Strong-ARM games. The way this is done is only suitible for development purposes though. I wouldn't expect stella to support this new format until there were enough games released to make it worth while. TLDR; if you use this framework you should expect your game to only be playable on unocart. The entire tech stack is open source. That should minimize the risk of developing for a platform that gets abandoned. If you provide more details about exactly what you're planning on building. I'd be happy to provide more details about how well suited this framework would be.
  9. That's great. I can take care of building a new firmware updater with the new firmware once you're done and also with testing everything.
  10. Have you tried generating a log of all the bus activity while the game is running? I think if you posted a log you'd get some help with figuring out how the customized chip works. You could hack together a data logger with an uno-cart and a Y adapter. Customizing the uno-cart firmware to be a datalogger is fairly trivial and a Y adapter would just require a few connectors, a donor pcb and some patience to solder everything.
  11. You could also position the first copy far enough right so the second copy wraps around to the left side of the screen.
  12. Keep in mind the peripheral clock is typically slower than the core CPU clock. You're correct though. It's possible to get a stable address that is not the next actual address. In practice this isn't really an issue because it's no different than having a really fast rom. There will be some transient values driven on the data bus while the address settles down, but eventually the correct address/data pair are produced and because there's a considerable delay between when the address is valid and the data is read it's always sorted itself out in time. The one exception to this is pitfall 2 because a lot more processing is done for each address and sometimes this can trip it up. I made a custom firmware build that logged the stable addresses to SD card when we were troubleshooting an issue with a specific system. On my 2600 jr it would pick up at least one wrong address for every right address. You could poll for longer but the problem with that is it increases latency and could lead to a failure to service the data bus in time. To get around this problem and allow useful work to be done in place of the address polling I keep track of what the next ROM address would be and wait for the address bus to be set to that before proceeding to update the data bus. This allows the data value to be calculated in advanced and also eliminates servicing any transient address values. The only downside is that you have to emulate enough of the 6502 to know which rom address comes next. For my purposes it's not difficult since I run all my game logic in ARM and only use a few load/store instructions to update the TIA registers. That project is also open source.
  13. Why don't you start posting some graphics? If you provide some screen mockups you'll get feedback on what is and isn't possible with a classic 4/8k game. You'll have a better chance at recruiting programmers or programming it yourself if the game design is well documented and properly matched to the 2600 limitations.
  14. I posted a separate topic with bin herehttp://atariage.com/forums/topic/279712-raycasting-with-bus-stuffing-demo/?fromsearch=1
  15. Exactly. What's involved in making a faithful port is fundamentally different than making an original game. This is why I think ports deserve their own category. Separating them does not imply that either approach is better or easier.
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