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Zerosquare

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Posts posted by Zerosquare

  5. Posted

    Since the (S)catbox includes networking, it probably drives the UARTI signal all the time. And according to @SainT, the JagGD needs UART communication to work. Unfortunately, the way the Jaguar is designed means that the UART signal from the DSP port has precedence over the one from the cartridge.

     

    One way to fix it would be to modify the Scatbox to add a switch in series with pin 3B:

    dsp_port.png

    • Like 1

  11. Posted · Edited by Zerosquare

    7 hours ago, cubanismo said:

    Maybe it's because I played a lot of Virtua Racing.

    Upon seeing Checkered Flag for a first time, a friend who's a Megadrive fan described it as "this is basically Virtua Racing, but done wrong".

    So it's pretty surprising you like it, given how much worse it is compared to the "original".

    • Haha 2

  14. Posted

    The internal UARTI signal is connected directly to the expansion port, but is connected to cart pin B30 thru a 1k resistor. So in theory, if the device connected to the expansion port has strong enough output drivers, it should override the JagGD's signal.

     

    Maybe it could be possible to make "buffered" JagLink adapters for people who already bought a JagGD. (They'd have to hotplug it after launching the game, if the GameGD needs UART comms to run the menu.)

     

     

     

    • Like 1

  17. Posted

    Mouse support requires reading the joystick registers very frequently (ideally about 2000 times per second), as opposed to only once per frame for the standard joypad. It may not be easy to integrate this into the Doom source code without causing performance impacts.

     

    Still, an interesting idea indeed.

    • Like 2

  19. Posted

    14 hours ago, bhall408 said:

    Had that also included the the Jaguar firmware/bios? (jagboot) Or just that development for Jaguar was then considered "open"?

    You don't need the boot ROM to run games anyways. The only thing it does is initialize the hardware, check the cartridge's digital signature and display the boot animation.

    • Like 2
    • Thanks 1

  21. Posted

    1 hour ago, agradeneu said:

    Why that? Comparing a cart system with a cart system is fair.

    ...if you're willing to disregard the massive difference in price, both for the system and the cartridges. And the fact that this difference is the reason why the NeoGeo hardware could achieve what it did back in 1990 or so.

     

    1 hour ago, agradeneu said:

    And why would the CD system be the preferable one? As far as I know it was never popular and the cart system was the preferable one. A well known downside of the NEOGEO CD system is that it has very long loading times and makes the system even more  expensive and unaffordable.

    Because its design is closer to the Jaguar hardware: it doesn't require huge ROMs with fast and random access, instead the graphics data is loaded from CD-ROM and kept in RAM. A cartridge Jaguar game would load it from ROM instead (so the load time is negligible), but once it's done, the result is the same.

     

    1 hour ago, agradeneu said:

    It looks to me like you just want to throw in that RAM number, 4 appearently bigger and better than 2 MB, do the math, all questions answered? Not really.

    My point is: don't expect the Jaguar to achieve what the NeoGeo CD couldn't do, despite having twice as much dedicated memory than the Jaguar has in total.

     

    1 hour ago, agradeneu said:

    Is that really comparable to system RAM? What about bandwidht limit and RAM speed? What about bottlenecks? What about providing realistic numbers about "real world" data shifting capabilities?

    Can you provide anything of that?

    I could, if I had hours or days to spend doing benchmarking on both machines. Which I don't.

    But I could ask the same: where's your data? What code have you written on the Jaguar?

     

    1 hour ago, agradeneu said:

    Makes me wonder why every modern console system has a unified bus design then?

    Constraints on modern hardware are completely different from constraints on retro hardware, so the comparison makes little sense.

    SNK didn't use the multiple bus approach just because they were lazy. They used it because they couldn't have achieved the same performance otherwise.

     

     

     

     

    • Like 1
    • Confused 1

  22. Posted

    If you want to compare the Jaguar to the NeoGeo, you should compare it to the NeoGeo CD. The latter has 4 MB of RAM just for the graphics and several separate busses (while the Jaguar's total amount of RAM is only 2 MB, with a single bus). And even with that, it can't pull off all of the cartridge-based NeoGeo games.

    • Like 1
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