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Zerosquare

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Zerosquare last won the day on September 5 2018

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About Zerosquare

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  1. Isn't it basically how you wrote Jagtopia?
  2. Some people like claiming that programming the Jaguar is extremely complicated because there are too many hardware bugs. Maybe that MiSTer core is a solution for them, when they find out the real thing is not that bad after all
  3. Check the motherboard carefully for damaged traces. If all continuity checks pass, one possibility is that one (or several) of the bus buffer chips (U12, U14, U17, U19, U22, U26, U30, U31) is defective.
  4. Sir, this is the Jaguar forum...
  5. I've been informed that someone else in the Jaguar community has been working on a very similar project that's almost complete -- it's just not been announced publicly yet. Since there would be no point in having two different carts that do the same thing, I'll let this person unveil their project when they're ready. But I have another idea for a related project that's not quite the same thing. So, stay tuned
  6. Before replacing them, have you checked whether the output voltages are correct, and if not, if there is a short between output and ground?
  7. Yes, serial EEPROM is planned. There's nothing preventing you from using a sector in the Flash chip if you want to save the cost of the EEPROM chip, but you need to be 100% sure there's no way for the code to accidentally erase/write to the wrong sector, otherwise you can end up with a game that corrupts itself - that would be a nightmare if it happens after the game is in customer's hands. Another possible issue is that all Flash chips don't have the same blocks layout ; it doesn't matter if you always use the same chip, but we've had to change the chip model several times on the Jagtopus because the previous was either out-of-stock or discontinued.
  8. The boards would be sold with all the components soldered, you'd only have to program them. This is both for technical reasons, and because I know not all developers like playing with a soldering iron Not yet. It depends on several things: memory size, banking scheme implementation, whether I can find a factory in China with both decent quality and competitive prices (I know a few of them, but I'd have to benchmark them)... "Just pulling the trigger" may be optimistic ; I have the theory laid out, and a partially completed older design. It was based on discrete logic though, which may not be the best solution now that I've revisited the idea. Let's say I'm not starting from scratch More than 16 MB would certainly be possible, the main limitation is memory prices (parallel NOR Flash is significantly more expensive than the serial NAND Flash that's used in memory cards and SSDs). Exactly ; not relying on old EPROMs was one of the main goal of the original Jagtopus boards, ten years ago. It turned out that the supply of EPROMs did not dry up like I was expecting (the amount of old/recycled parts you can get from China is amazing...), but you still have more guarantees with new parts. @SCPCD is the one who designed and manufactured the programmers; I don't remember their cost exactly, but it was several hundreds euros if memory serves, not including the time he spent soldering and testing them (which is why only 3 or so of them have been manufactured). Ouch -- I had no idea the stocks levels were so low! Thanks for the warning.
  9. Besides the $800000 ~ $DFFFFF cartridge ROM area, the Jaguar has a few other areas that are accessible over the cartridge bus: GPIO0 & GPIO1 are not available (they control the cartridge's EEPROM), but other should be usable to put the banking register(s) in. The register(s) bit layout has not been decided yet, it will depend on the banking scheme. Yeah, I should have put a link to the Jagtopus v1 thread for info: I have not set a target price yet. I prefer to evaluate the various options first. Yeah, "real" gold (as opposed to flash gold, which is just a very thin layer) is expensive There are two existing options for programming Jagtopus PCBs: - uploading the code from a PC thru the 2nd joystick connector. But since the throughput is limited, it would probably be too cumbersome for 8+MB games. - using an external programmer designed by SCPCD. It's a much better option for mass production, since it can program 4 PCBs in parallel. But the hardware is not cheap (the design hasn't been optimized for cost, and the 4 cartridge connectors alone are pricy). Using the JagCD is a possibility, but my religion forbids me from even looking at that thing (seriously though, anyone wishing to try it is welcome, but don't expect me to.) Using a JTAG programmer may be an option, but that requires a CPLD with connections to the entire address and data buses, which may raise the price. One possibility I've considered is a modified Jaguar: the ROM image would be stored on a SD card connected to the joystick or DSP port, and a custom BIOS would automatically program the Jagtopus PCB.
  10. Yes, bankswitching is needed to make it work. The simplest scheme would be this: - $800000 ~ $BFFFFF: fixed area, always maps to the first 4 MB of the ROM - $C00000 ~ $DFFFFF: configurable area, can be switched to any bank More elaborate banking schemes are possible, but I don't yet know how they would impact the price (depends whether a small CPLD is significantly more expensive than discrete logic).
  11. Yes, scaled sprites take longer to be processed by the object processor than standard ones, even at unity zoom.
  12. A few years ago, I started working on the next version of the programmable Jagtopus cartridge. I wanted to add support for larger Flash memories (8 MB and up) and larger save EEPROMs (say, 32 kB), and maybe a few other extras. I designed a schematic, started routing the PCB, then I got distracted by other projects and never finished it. To be honest, the lack of demand for bigger carts was also a factor. Recently, there have been talks of projects needing more than 4 MB of ROM. Yeah, I know what's you're thinking: what's the point of such a project, now that the JagGD exists? Well: - not everybody has one - some people prefer physical cartridges over SD cards or digital downloads, either because they like collecting physical stuff, or because they feel part of the nostalgia is using the console like it was used back in the day. Here's where I need your feedback. As homebrew developers: - what do you think of the idea? - would such a product be useful to you, and if so, how would you use it? - besides the larger memories, are there any extra features you'd find useful? (please note that unlike the Skunkboard and the JagSD, this would be a cost-optimized design for releasing games, not a development tool or a multicart. So don't expect anything too fancy ;)). At the moment, this is just a potential interest check. No promises, no preorder lists, nothing has been decided yet
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