Pinned Latest news on Atomiswave 2 Naomi

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    • MetalliC wrote:

      @Dreygor short answer: there is no sense

      longer version:
      these conversions suffers from significant slowdowns here and there, afaik that's the only problem. it is unknown why this happen and I have no ideas why.
      ofc, you may poke Darksoft, he in it's turn as usual will poke me, and it will ends with nothing (read above - no ideas about the cause of problem = unknown what should be fixed)
      this happens because there is an AW loader for Naomi in these roms that act as some sort of broker that copies data from the dimm instead of the original cart location, that code is however poorly optimized from what I have seen and uses PIO for transfers instead of DMA, which is the cause of the slowdowns. You would have to rewrite the AW loader properly so it uses DMA.
    • MetalliC wrote:


      mathieulh wrote:

      that code is however poorly optimized from what I have seen and uses PIO for transfers instead of DMA, which is the cause of the slowdowns. You would have to rewrite the AW loader properly so it uses DMA.
      miss. Joerg already tried that, and rewrote cart access "in optimized way" using DMA.it didn't helps, games still slowdowns.

      any other ideas ? ;)


      Hum... is there any sample of the code he used ? I have only seen the code from the metal slug 6 conversion that definitely used PIO.
    • not sure if it public, it was one of unreleased AW games, converted by Joerg per private request. it was few years ago, but iirc I've examined/analyzed cart access DMA code and didn't noticed some mistakes.
      so, back to my prev message - no good ideas from me...

      add:
      @mathieulh if being a bit more tech detailed - I tend to think it is same thing known as "G1 DMA clash", which was observed in some of NAOMI cart to DIMM conversions. however it produced different effect there - bad data was DMA'ed, which was hacky fixed by replacing DMA with PIO in games.
      to my knowledge, it is known to Sega DIMM-specific (hardware-level ?) bug, which was addressed and fixed in theirs newer NAOMI 1/2 SDK and BIOS revisions.
      much probable AW hardware doesn't had this bug, so games was designed with no workarounds for it.

      The post was edited 4 times, last by MetalliC ().

    • FWIW, I definitely notice a lot more slowdown on Dolphin Blue on Naomi as compared to the original hardware/cart. I am glad to have made the shift for that one game i particular.
      Multis: CPS-1, CPS-2, CPS-3, F3, S16, ST-V, MVS, AES, M72, Crystal System, G-Net, Naomi, TTX2
      Screens: 2043MD, 20M2MDA, 20L2MD, AR25M31, XR29M31, BL2411PT, BL2700HT
      Devices: Sentinel Gold / Ultracade uVC / JAMMAizer! / Framemeister XRGB-mini
      PCBs: VAPS Profile
    • mathieulh wrote:

      The best bet would be to attempt to replicate the slowdowns in an emulator to figure out what's going on perhaps ? For example by artificially slowing down memory transfer speeds perhaps ?
      sure thing, but sadly, neither of emulators is accurate performance-wise.
      and Dreamcast/NAOMI DMA part is still black box: HOLLY chipset have number of DMAs - G1/ATA(cart/GD-drive), G2 (sound RAM), video RAM access, etc. most of these uses SH-4 CPU's DMA channel 0 in DDT mode (on-demand DMA mode, channel controlled by external device, HOLLY).
      but, games might start several different type DMA requests at once, and available docs have no restrictions of this. so, how do this works in the same time but using single DMA channel 0 ? - we don't know, HOLLY chipset probably somehow schedule all the requests, divide in smaller transfers and push to SH4's DDT in mixed order.
      but that's just my guesswork...

      there is also 200MHz SH-4 CPU itself, which effective speed may vary from like "50MHz" equivalent (in case of many cache miss / slow MMIO or memory access, etc), up to "400MHz" equivalent if everything runs from cache and code is optimized for superscalar execution (2 instructions in parallel).
      so, effective CPU speed may vary like x8 times, and neither of emulators even trying to emulate this, but just running CPU core at some specific clock...
    • Sp33dFr34k wrote:

      djsheep wrote:

      FWIW, I definitely notice a lot more slowdown on Dolphin Blue on Naomi as compared to the original hardware/cart. I am glad to have made the shift for that one game i particular.
      Seriously? Any chance for a side by side comparison vid?
      No method to record side-by-side, I’m still on a Framemeister and elGato game capture HD :). The slowdown on Dolphin Blue is known to be “normal”. But on original hardware it never slows down to a halt like it does at times on the NetBoot. I’m almost certain of this issue, I have read others complain about the same thing on Shmups forum. The original hardware plays a lot smoother, at least that’s how it feels to me.
      Multis: CPS-1, CPS-2, CPS-3, F3, S16, ST-V, MVS, AES, M72, Crystal System, G-Net, Naomi, TTX2
      Screens: 2043MD, 20M2MDA, 20L2MD, AR25M31, XR29M31, BL2411PT, BL2700HT
      Devices: Sentinel Gold / Ultracade uVC / JAMMAizer! / Framemeister XRGB-mini
      PCBs: VAPS Profile
    • djsheep wrote:

      Sp33dFr34k wrote:

      djsheep wrote:

      FWIW, I definitely notice a lot more slowdown on Dolphin Blue on Naomi as compared to the original hardware/cart. I am glad to have made the shift for that one game i particular.
      Seriously? Any chance for a side by side comparison vid?
      No method to record side-by-side, I’m still on a Framemeister and elGato game capture HD :). The slowdown on Dolphin Blue is known to be “normal”. But on original hardware it never slows down to a halt like it does at times on the NetBoot. I’m almost certain of this issue, I have read others complain about the same thing on Shmups forum. The original hardware plays a lot smoother, at least that’s how it feels to me.
      You got me curious, maybe record them seperately then and edit to have them side by side later? :D
    • If I ever get the proper means to record arcade, I will.

      Maybe this random video I pulled from YouTube will show the difference perhaps:
      Multis: CPS-1, CPS-2, CPS-3, F3, S16, ST-V, MVS, AES, M72, Crystal System, G-Net, Naomi, TTX2
      Screens: 2043MD, 20M2MDA, 20L2MD, AR25M31, XR29M31, BL2411PT, BL2700HT
      Devices: Sentinel Gold / Ultracade uVC / JAMMAizer! / Framemeister XRGB-mini
      PCBs: VAPS Profile
    • New

      Just an FYI, if anyone happens to come across this issue, the original Guilty Gear Isuka rom conversion has a bug where it crashes after the first round of a game ends.

      I've tested this on a Naomi 2 board, with an original B bios and the latest multi bios. It has the same results. Game boots fine, plays the first round of any game and then as soon as the round ends, it just locks up with a black screen.