The X68000 games porting experiment - Page 4

meynaf · 29 September 2015, 17:01

Quote:

Originally Posted by AnimaInCorpore

However, you should be aware that up to 512 sprites (16 x 16 pixels) are being displayed on the screen simultaneously.

It looked just too easy. I knew there would be something bad somewhere...

AnimaInCorpore · 29 September 2015, 17:16

Quote:

Originally Posted by meynaf

It looked just too easy. I knew there would be something bad somewhere...

Yeah that really hurts. That's the reason why I had to add a frame skip routine.

Retro1234 · 29 September 2015, 19:13

Where most games written in C rather than Asm for the x68000? Is there anyway you can do a all cpu no blitter version that would run on both Atari and Amiga?

What was the point of games being rewriten back in the day for 68k machines from scratch like the Atari ST and Amiga when they had already be written for 68k the x68000

saimon69 · 29 September 2015, 19:31

@Boo Boo

I have the feeling is a mix of factor between resources (use a 030 like in falcon to run a game that runs on a 68000 in the original), rights (companies would not like other to reverse engineer their code), pride (japanese in the 90 still convinced to be the best plus the rights as above) and ignorance (i not even knew x68000 existed if was not for a computer mag - technopolis - that the father of a friend of mine brought back from Japan) - ah add greed (probably companies thought reverse engineering was more complex and less result-prone than rewrite the whole thing and they did want fast dough so no risk taken)

Retro1234 · 29 September 2015, 19:45

The basic machine was 68000, if they were buying the license why not ask for the C source this was the development machine as I understand?
I guess the machince graphics is above the blitter. It seems some Euro games made there way to the x68000 xenon2.
The x68000 adeverts have pictures of tutankhamun witch is one of the big Dpaint things.
Also it would be cool to see Aros on the x68000 - I realy like this computer but I would miss all the independent games and I dont think it has many intresting apps.

saimon69 · 29 September 2015, 20:11

@Boo Boo
i throw hints at Falcon and x68k communities once in a while to port AROS but guess they are not interested

AnimaInCorpore · 30 September 2015, 18:24

Quote:

Originally Posted by Boo Boo

Where most games written in C rather than Asm for the x68000? Is there anyway you can do a all cpu no blitter version that would run on both Atari and Amiga?

No, Cho Ren Sha 68k is an exception. Most games have been written in assembler for the X68000.

I think that it would be easy to have a first version which would run on the Amiga as well (without graphics). The problem here is that I have no experience on the Amiga.

Quote:

Originally Posted by Boo Boo

What was the point of games being rewriten back in the day for 68k machines from scratch like the Atari ST and Amiga when they had already be written for 68k the x68000

The graphics and sound capabilities of the systems are too different. Most games of that era have been developed very tightly on the system specific features so that an easy port is almost impossible. Also the different memory configurations are limiting the possibilities. However, the X68000 porting experiment might prove that this isn't always true...

Porting games between MC68000 based systems mainly depends on how the graphics and sound routines can be replaced. This approach works well on the X68000 because the graphics system is quite simple. However, the Videl processor (16 bit colours and flexible graphic modes) on the Atari Falcon was really helpful for this task.

Jack Burton · 30 September 2015, 23:35

Hi Sascha ! You did a great port of Cho Ren Sha !

I spent quite some time playing Cho Ren Sha on my Falcon during my summer holidays.

Anyway, there is a bug from time to time : an enemy ship that normally appears on the middle of the screen suddenly cross the screen from top to bottom at a lightning speed, it's so fast that it is impossible to dodge it so it results to an instant destruction of the player. And each time this bug appears, then when you exit the game, the screen becomes black. It's impossible to go back to the TOS. Did you ever experienced this bug ?

AnimaInCorpore · 01 October 2015, 17:15

Quote:

Originally Posted by Jack Burton

Hi Sascha ! You did a great port of Cho Ren Sha !

I spent quite some time playing Cho Ren Sha on my Falcon during my summer holidays.

Thanks!

Quote:

Originally Posted by Jack Burton

Anyway, there is a bug from time to time : an enemy ship that normally appears on the middle of the screen suddenly cross the screen from top to bottom at a lightning speed, it's so fast that it is impossible to dodge it so it results to an instant destruction of the player. And each time this bug appears, then when you exit the game, the screen becomes black. It's impossible to go back to the TOS. Did you ever experienced this bug ?

That's really strange. So the bug does not occur all the time? When exactly did that happen. Are there any special programs loaded before starting the game?

ReadOnlyCat · 02 October 2015, 06:33

Quote:

Originally Posted by frank_b

That's an *unaccelerated* Falcon I believe. IE DSP, blitter + 16 mhz CPU.

One can do pretty crazy things with a stock Falcon. Cf Douglas Little's ongoing work on the Quake2 engine: https://m.youtube.com/playlist?list=...Ww_M5nMm10m0UM (watch the playlist in reverse to get a chronological evolution).

The true color mode and DSP can really make a difference if one is willing to spend the time needed to carefully parallelize work between the CPU and DSP.

I guess we were lucky that Atari messed up the Falcon's CPU bus.

frank_b · 02 October 2015, 10:11

Did they? It is 16 bit but at 16 MHz. The data cache also works on chip ram access unlike Amigas. Remember the stock 1200 is 32 bit but chip ram is only 7 MHz. "Chip" memory access is faster on a Falcon. 16 bit memory access is faster than a 1200. Just add on accelerator fast ram to both.

Leffmann · 02 October 2015, 11:51

It's yet a bit worse on the Amiga, because even if the AGA chip bus runs at 7 MHz, it's effectively only 3.5 MHz for the CPU and the Blitter, just like on OCS and ECS. Only the bitplane DMA ever gets any performance benefit from the 7 MHz bus.

frank_b · 02 October 2015, 12:25

Quote:

Originally Posted by Leffmann

It's yet a bit worse on the Amiga, because even if the AGA chip bus runs at 7 MHz, it's effectively only 3.5 MHz for the CPU and the Blitter, just like on OCS and ECS. Only the bitplane DMA ever gets any performance benefit from the 7 MHz bus.

Indeed. The Falcon is quite a bit faster here. It's also much faster on VGA displays.

AnimaInCorpore · 02 October 2015, 12:47

Quote:

Originally Posted by ReadOnlyCat

I guess we were lucky that Atari messed up the Falcon's CPU bus.

Well, just consider this: if Atari would have added an 8 bit chunky pixel graphics mode, Cho Ren Sha 68k would've been more than twice as fast.

ReadOnlyCat · 02 October 2015, 15:20

Quote:

Originally Posted by Leffmann

It's yet a bit worse on the Amiga, because even if the AGA chip bus runs at 7 MHz, it's effectively only 3.5 MHz for the CPU and the Blitter, just like on OCS and ECS. Only the bitplane DMA ever gets any performance benefit from the 7 MHz bus.

My, what a disaster.
Yeah, I guess the Falcon's bus is not that messed up in the end.

frank_b · 02 October 2015, 16:40

Quote:

Originally Posted by ReadOnlyCat

My, what a disaster.
Yeah, I guess the Falcon's bus is not that messed up in the end.

Easily solved with a fast ram expansion on both

Jack Burton · 02 October 2015, 18:15

Quote:

Originally Posted by AnimaInCorpore

That's really strange. So the bug does not occur all the time?

Yes, it only appears from time to time.

Quote:

When exactly did that happen. Are there any special programs loaded before starting the game?

No, there are no programs loaded before, I just start the Falcon and then load Cho Ren Sha. I use ICD though. Could it be related to ICD ?
Anyway this bug appears only once in a while, I would say 10%-15% of the time so it's not that annoying after all. But I was wondering if it was a known bug.

Jack Burton · 02 October 2015, 18:19

Quote:

Originally Posted by Leffmann

It's yet a bit worse on the Amiga, because even if the AGA chip bus runs at 7 MHz, it's effectively only 3.5 MHz for the CPU and the Blitter, just like on OCS and ECS. Only the bitplane DMA ever gets any performance benefit from the 7 MHz bus.

Does it means that the Amiga Blitter runs at 3.5 Mhz ? (I always thought it ran at 7 Mhz)

frank_b · 02 October 2015, 18:36

Quote:

Originally Posted by Jack Burton

Does it means that the Amiga Blitter runs at 3.5 Mhz ? (I always thought it ran at 7 Mhz)

The blitter on the Amiga can use unused DMA slots.

AnimaInCorpore · 02 October 2015, 18:38

Quote:

Originally Posted by Jack Burton

No, there are no programs loaded before, I just start the Falcon and then load Cho Ren Sha. I use ICD though. Could it be related to ICD ?

Thanks for the reply. I am using HD Driver so this is indeed a difference but it shouldn't make a difference at all.

Quote:

Originally Posted by Jack Burton

Anyway this bug appears only once in a while, I would say 10%-15% of the time so it's not that annoying after all. But I was wondering if it was a known bug.

So far I've got no report on any bugs. Care to elaborate how I can reproduce the bug? E.g. how long do I have to play to observe it?

02 October 2015, 10:11	#71
frank_b Registered User Join Date: Jun 2008 Location: Boston USA Posts: 466	The X68000 games porting experiment Did they? It is 16 bit but at 16 MHz. The data cache also works on chip ram access unlike Amigas. Remember the stock 1200 is 32 bit but chip ram is only 7 MHz. "Chip" memory access is faster on a Falcon. 16 bit memory access is faster than a 1200. Just add on accelerator fast ram to both. Last edited by frank_b; 02 October 2015 at 12:29.

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29 September 2015, 19:13	#63
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,773	Where most games written in C rather than Asm for the x68000? Is there anyway you can do a all cpu no blitter version that would run on both Atari and Amiga? What was the point of games being rewriten back in the day for 68k machines from scratch like the Atari ST and Amiga when they had already be written for 68k the x68000

29 September 2015, 19:31	#64
saimon69 J.M.D - Bedroom Musician Join Date: Apr 2014 Location: los angeles,ca Posts: 3,519	@Boo Boo I have the feeling is a mix of factor between resources (use a 030 like in falcon to run a game that runs on a 68000 in the original), rights (companies would not like other to reverse engineer their code), pride (japanese in the 90 still convinced to be the best plus the rights as above) and ignorance (i not even knew x68000 existed if was not for a computer mag - technopolis - that the father of a friend of mine brought back from Japan) - ah add greed (probably companies thought reverse engineering was more complex and less result-prone than rewrite the whole thing and they did want fast dough so no risk taken)

29 September 2015, 19:45	#65
Retro1234 Phone Homer Join Date: Jun 2006 Location: 5150 Posts: 5,773	The basic machine was 68000, if they were buying the license why not ask for the C source this was the development machine as I understand? I guess the machince graphics is above the blitter. It seems some Euro games made there way to the x68000 xenon2. The x68000 adeverts have pictures of tutankhamun witch is one of the big Dpaint things. Also it would be cool to see Aros on the x68000 - I realy like this computer but I would miss all the independent games and I dont think it has many intresting apps.

29 September 2015, 20:11	#66
saimon69 J.M.D - Bedroom Musician Join Date: Apr 2014 Location: los angeles,ca Posts: 3,519	@Boo Boo i throw hints at Falcon and x68k communities once in a while to port AROS but guess they are not interested

30 September 2015, 23:35	#68
Jack Burton It's all in the reflexes! Join Date: Nov 2009 Location: Wingkong warehouses Posts: 206	Hi Sascha ! You did a great port of Cho Ren Sha ! I spent quite some time playing Cho Ren Sha on my Falcon during my summer holidays. Anyway, there is a bug from time to time : an enemy ship that normally appears on the middle of the screen suddenly cross the screen from top to bottom at a lightning speed, it's so fast that it is impossible to dodge it so it results to an instant destruction of the player. And each time this bug appears, then when you exit the game, the screen becomes black. It's impossible to go back to the TOS. Did you ever experienced this bug ?

02 October 2015, 11:51	#72
Leffmann Join Date: Jul 2008 Location: Sweden Posts: 2,269	It's yet a bit worse on the Amiga, because even if the AGA chip bus runs at 7 MHz, it's effectively only 3.5 MHz for the CPU and the Blitter, just like on OCS and ECS. Only the bitplane DMA ever gets any performance benefit from the 7 MHz bus.

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