08 December 2018, 22:23 | #1 |
Registered User
Join Date: Mar 2015
Location: Sheffield UK
Posts: 360
|
Immediate Blitter & Wait for Blitter...
Just a question....
Is Immediate blitter mode more or less compatible with real hardware? |
08 December 2018, 22:25 | #2 |
Defendit numerus
Join Date: Mar 2017
Location: Crossing the Rubicon
Age: 54
Posts: 4,491
|
|
09 December 2018, 00:28 | #3 | |
Going nowhere
Join Date: Oct 2001
Location: United Kingdom
Age: 50
Posts: 9,016
|
Quote:
Of course not waiting for the blitter to finish before doing another blit seems stupid, but when programmers thought they were only ever going to be dealing with a 68000 Amiga and not 68020+, then the games they programmed ran without problems and no graphic corruption. |
|
09 December 2018, 06:57 | #4 |
Registered User
Join Date: Sep 2017
Location: Kansas, USA
Posts: 329
|
You're describing the "Wait for Blitter" setting. Immediate Blitter is the "turbo blitter" setting that makes blits finish immediately instead of trying to simulate a realistic blitter speed, nice for speeding up some software, or horribly breaking others.
|
09 December 2018, 09:11 | #5 |
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 49
Posts: 26,570
|
"Wait for blitter" works like normal unless CPU attempts to access blitter registers while previous blit is still active. In this case it temporarily halts the CPU and releases it when previous blit has finished.
|
09 December 2018, 12:12 | #6 |
Old retro god.
Join Date: Apr 2002
Location: Northolt, West London
Age: 62
Posts: 858
|
Hi Toni (or anyone tech enough to answer correctly),
What is it that makes the emulator still need these immediate blit settings, what stops the emulation from handling it exactly as the hardware? I ask simply because I've seen the emulation come on in area's I thought were already complete and in other places where it feels like it is a real 1200 or A500 being used. That's a huge credit to you and the dedication to emulation completeness but what and I imagine its the PC architecture, is holding back those blit items? Too tight a need for cycles, no processor time to match? I guess the real question is can those settings ever be irradiated? And hey, no throwing the crystal ball, do you know how hard it is to try and find if this question has been answered with the right set of searches Paul... |
09 December 2018, 12:50 | #7 | |
move.l #$c0ff33,throat
Join Date: Dec 2005
Location: Berlin/Joymoney
Posts: 6,863
|
Quote:
No. They are useful. |
|
09 December 2018, 14:14 | #8 |
Old retro god.
Join Date: Apr 2002
Location: Northolt, West London
Age: 62
Posts: 858
|
But surely that's a bastardisation of emulation and basically a 'hack', technically should the code not run as it was intended to run on the desired emulated machine with maybe a 'special machine choice for situation where the emulation is wanted to cheat
Basically it sounds like its making a Frankenstein emulation choice? (I can hear that crystal ball spining up on its mega fast journey to the side of my head) Just interested and with all the many many emulators I've tested (trust me, I go back before the Ark!) the real aim has been to get the emulator as a near perfect match for the real machine. |
09 December 2018, 14:22 | #9 |
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 49
Posts: 26,570
|
Lots of users use JIT and fastest possible (=faster than any real accelerator). Immediate blitter is very easy hack to fix most common program bug in blitter handling. EDIT: no user wants to see graphics glitches and would blame it emulator bug even if it also happens when using real 68040+ system.. This is not the only compatibility hack which is enabled when fast mode is enabled. Audio is another, lots of programs would become totally silent or miss notes without hack. (cpu loop "dma wait").
Accurate 68020+ CPU emulation is also extremely complex (and currently practically impossible to emulate 100% because internal cycle sequences are unknown) and not really worth it unless you want to emulate plain unexpanded A1200. Most other 8/16-bit platforms does not have so huge CPU/memory performance difference between different configurations (unexpended vs 68040+ accelerator board) |
09 December 2018, 15:10 | #10 | |
Banned
Join Date: Aug 2005
Location: London / Sydney
Age: 47
Posts: 20,420
|
In my collection, out of 2600 configurations, these 16 games need "Immediate Blitter" ticked otherwise there are small issues:
Quote:
|
|
09 December 2018, 16:04 | #11 | |
Defendit numerus
Join Date: Mar 2017
Location: Crossing the Rubicon
Age: 54
Posts: 4,491
|
Quote:
As 'immediate blitter' is an unnatural requirement, these used versions need a fix. Can you somehow remember/derive what is the glitch they present? |
|
09 December 2018, 16:39 | #12 | |
I Identify as an Ewok
Join Date: Jul 2001
Location: North Lincolnshire
Age: 45
Posts: 2,356
|
Quote:
It only works if you select 'immediate blitter' from the start of emulation. See attached screenshots. |
|
09 December 2018, 16:43 | #13 |
Going nowhere
Join Date: Oct 2001
Location: United Kingdom
Age: 50
Posts: 9,016
|
Just to clarify what Ross is saying and DamienD's findings are.... if a game was written with a 68000 A500 in mind AND has graphical problems on a real A500 because of the blitter, then the game itself is buggy, NOT WinUAE.
WinUAE is correcting a problem that shouldn't occur on a 68000, its generally to fix problems with faster processors. So if any on that list that Damien has provided have problems on a real A500, then as Ross said, they require fixing. Although G-Loc 360 is such a pile of shit, I couldn't bring myself to boot it up again. |
09 December 2018, 17:04 | #14 |
Old retro god.
Join Date: Apr 2002
Location: Northolt, West London
Age: 62
Posts: 858
|
So in some respects its correcting abnormal configurations rather than out of the box machine specs, that would make sense and a fair fix but shouldn't those users using 68030 cpus etc expect a bit of an issue here and there, I know I had all sorts with my 68030 board in my 1200.
I understand folk would moan at the emu rather than these future based upgrades to the initial machines and I can see a reason to help them, I presume adding the immediate blitter does not cause any problems in non fixing needed games? I'm not trying to pick holes in the emulator, it just was a question I meant to ask ages ago and for the emulation purists it seems a weird thing to add hacks to fix poor programming if it would cause the same issue on the real hardware. I hope people understand where I'm coming from, like I say I was around when home computers were not even out and my living was selling old (boo hiss) Atari 8 bit machines so I've seen soo many emulators come, go or stay and often got involved in beta testing them so precise emulation always seemed the main aim with as few (if any) hacks as possible.. |
09 December 2018, 17:49 | #15 | |
Going nowhere
Join Date: Oct 2001
Location: United Kingdom
Age: 50
Posts: 9,016
|
Quote:
So with the release of the A1200 and A4000, people simply expect software to work on them, because lots of software did, without problems. WinUAE is a great emulator, and if you keep it to precise settings, games written for A500 that had graphical problems on a real A1200 will look the same in emulation.... i.e. the same graphical glitches will occur. However, forcing a user to only experience games through emulation as precisely as possible doesn't always lend itself to a great emulation experience. What you have to remember is that lots of people using WinUAE, didn't EVER have an Amiga back in the day, they don't care why a game doesn't work correctly, they don't understand why it doesn't work correctly, but if they are told "tick this box to fix graphic glitches" and that option works, then they will be happy and WinUAE is doing its job. In the same way that people did AGA fixes for A1200 to fix A500 games to work on faster machines, most people didn't understand why the games didn't work, they just wanted them to work. For those of us that need WinUAE to act like a real Amiga, it can and does. |
|
09 December 2018, 19:48 | #16 | |||
move.l #$c0ff33,throat
Join Date: Dec 2005
Location: Berlin/Joymoney
Posts: 6,863
|
Quote:
Of course it's a "hack" and if games/demos were coded with faster CPUs in mind it wouldn't be necessary. Quote:
Quote:
|
|||
09 December 2018, 20:30 | #17 | |
Banned
Join Date: Aug 2005
Location: London / Sydney
Age: 47
Posts: 20,420
|
Quote:
...not off the top of my head; except for these:
|
|
09 December 2018, 22:17 | #18 | |||
Defendit numerus
Join Date: Mar 2017
Location: Crossing the Rubicon
Age: 54
Posts: 4,491
|
I looked quickly so I might have overlooked something:
Quote:
Balls are sprites so unrelated with blitter, maybe your setting miss a CE opt and for a few different cycles there are desyncs? Or something in recent WinUAEs solved it? Quote:
Can be that you have disabled CE to speed up the game(s)? Quote:
But for a faster processor there are glitches everywhere due to a tight sync between CPU and blitter that is no more. So yes, on 020+ you need patched intro code or 'immediate blitter' in WinUAE Ciao! |
|||
09 December 2018, 22:31 | #19 | |||
Banned
Join Date: Aug 2005
Location: London / Sydney
Age: 47
Posts: 20,420
|
Quote:
Quote:
Quote:
Feel free to check the others I've listed if you can be bothered |
|||
10 December 2018, 13:08 | #20 |
Zone Friend
|
Got myself a bit confused here .... So which is combo the most 'accurate' to the hardware: Ticking 'Wait for blitter' or leaving it unticked? I'm guessing ticking 'Immediate blitter' unticks 'Wait for blitter' (and vice versa), but if they're both unticked does it wait for blitter or not ?!
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Blitter C2P? How? | Samurai_Crow | Coders. Asm / Hardware | 21 | 24 April 2018 19:12 |
"Wait for Blitter"... | DamienD | support.WinUAE | 3 | 01 April 2017 21:09 |
Blitter Mimterm Help | sandruzzo | Coders. Asm / Hardware | 7 | 19 April 2016 17:52 |
Blitter busy flag with blitter DMA off? | NorthWay | Coders. Asm / Hardware | 9 | 23 February 2014 21:05 |
Please help me!! Blitter pain! | h0ffman | Coders. Asm / Hardware | 5 | 15 June 2013 18:59 |
|
|