17 April 2024, 17:09 | #241 |
PSPUAE DEV
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17 April 2024, 17:40 | #242 | |
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The bottleneck in this game, is the DMA slots available to the blitter. The logic code running in fast RAM, should run mostly by itself, except when building copperlists (including blit queues) in chip mem. DMA slots for blitter are limited by other devices access to chip mem. Of those devices audio, copper, bitplane dma are 100% emulated afaik, because they are mostly the same as OCE/ECS, except for the FMODE 4 bitplane/sprite DMA, which I believe is also 100% emulated. The main unknown is the 68020 CPU's internal workings, including chip mem access. Since the code that accesses chip RAM is limited, I'm expecting similar (not identical) performance to WinUAE, for this setup only. Maybe Toni can correct/support me? Of course we will do lots of tests on real hw. Initial performance tests showed similar performance. Last edited by agermose; 18 April 2024 at 11:15. |
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17 April 2024, 17:43 | #243 |
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17 April 2024, 18:21 | #244 |
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17 April 2024, 18:45 | #245 | |
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17 April 2024, 19:09 | #246 | |
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Yes it is running in 4x bitplane mode. Last edited by agermose; 18 April 2024 at 11:15. |
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17 April 2024, 21:34 | #247 |
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To provide some clarity on WinUAE Cycle exact, it works just fine for DMA related things. But CPU speed is overestimated compared to the real deal, including the speed at which the CPU access Chip Memory.. I haven't done any tests on Fast RAM speeds, but I would not be surprised if it's too fast there as well.
Regardless, I've found that some things are way too fast on WinUAE and others not so much. I'd recommend testing on real hardware just to be sure, as I've personally found the 'real world 68020' to be much more fickle in when it does or does not perform well than the WinUAE version |
18 April 2024, 07:32 | #248 |
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In the last days I tested my A1200 with an A1208 expansion from Arca, it has a tool (A1208cfg) which permits to disable 4MB and enable only 4MB + 1,5MB of range ram, to use PCMCIA card.
The system with an updated OS3.1 it's quite usable with 8MB fast ram. I tested many old demos and these run well, but for some a good accelerator is needed. In the ninetees I owned an old Blizzard 1220/4 which gives 5,06 Mips in SysInfo and I could play also with emulators like AmiMasterGear, ZXAm, AmiMSX, AmiGameBoy. But now with the simple expansion (2,94 mips) all these emulators are quite slow, these run at 50% speed of original machines. Anyway I think that the best boost for a standard Amiga 1200 is a Blizzard 1230 or 68030 one. With this accelerator all is usable, playable, even some 68040/060 demos, with the FPU can run, altough at a more low framerate. In my opinion I think that OutRun on Amiga should requires at least a 68030 and Fast Ram. Running it with a 68020 + Fast configuration is simply a miracle |
18 April 2024, 09:05 | #249 | |
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My point was that for this game the CPU logic code takes less than a frame, to complete. Then it sits there waiting for the blitter to finish, which is about 2-4 frames in WinUAE. I would be surprised if the CPU code in fast mem slows down in real hw, to a point where the whole thing runs at a lower framerate. I may be proven wrong, that is why testing on real hw is a must. |
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18 April 2024, 09:38 | #250 |
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That makes a lot of sense, if your code spends a lot of time waiting on the chipset, it'll likely work out fine.
That said, in all honesty my comment was aimed more at the general discussion about emulation accuracy and not about your knowledge of these things. So if it came across differently, that was not the intent. |
18 April 2024, 10:59 | #251 | |
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Last edited by S0ulA55a551n; 18 April 2024 at 11:36. |
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18 April 2024, 11:13 | #252 | |
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If only someone could get those schematics to Toni, then we could have a better stomach feeling, when testing mainly in WinUAE |
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18 April 2024, 12:57 | #253 | |
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Most 68020 die photographs (including the link below) are just not high enough resolution to be of any use. https://blog.ehliar.se/post/80934423...torola-mc68020 |
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