Interesting discussion at YouTube :-)

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Interesting discussion at YouTube :-)

Postby AtariZoll » Wed Sep 09, 2015 6:31 am

https://www.youtube.com/watch?v=urgixT_ ... rioyhrpj4s

It was looong time since last Amiga vs Atari dispute here :D
I would like to hear some real Amiga disk speed experiences, not those based on some advertisements.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Interesting discussion at YouTube :-)

Postby Frank B » Wed Sep 09, 2015 6:46 am

AtariZoll wrote:https://www.youtube.com/watch?v=urgixT_MPCU&google_comment_id=z135wryw0lamep4a404cctf5crioyhrpj4s

It was looong time since last Amiga vs Atari dispute here :D
I would like to hear some real Amiga disk speed experiences, not those based on some advertisements.



Interesting. Is that using Doug's photochrome source and tech?

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Re: Interesting discussion at YouTube :-)

Postby alexh » Wed Sep 09, 2015 9:20 am

DFSilver is confused. 3.5MB/s is the theoretical maximum of the Zorro II bus the SCSI drive connects to. Drives cannot operate at that speed, especially when transferring to RAM which will be via arbitration.

Even with a special highly optimized driver called "GuruROM" the GVP SCSI Impact II can only do 1.7MB/s into chip memory (required for displaying video)

Don't believe me? Then here it is from the guy who wrote the firmware.

http://babel.de/amiga.html
Last edited by alexh on Wed Sep 09, 2015 12:53 pm, edited 1 time in total.

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Re: Interesting discussion at YouTube :-)

Postby Frank B » Wed Sep 09, 2015 9:54 am

alexh wrote:DFSilver is confused. 3.5MB/s is the theoretical maximum of the Zorro II bus the SCSI drive connects to. Drives cannot operate at that speed, especially when transferring to RAM which will be via arbitration.

Even with a special highly optimized driver called "GuruROM" the GVP SCSI Impact II can only do 1.7MB/s into chip memory (required for displaying video)

Don't believe me? Then here it is from the guy who invented the hardware and software.

http://babel.de/amiga.html


Yes. He will remain confused about the Amiga till he reads and understands the HRM. ;)
The DMA controller is a standard feature in the ST which is sadly missing on the Amiga. Still there's always IDE PIO mode 0. Slow as hell, CPU sucking but better than nothing. The GVP unit probably costs more than the ST too :)

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Re: Interesting discussion at YouTube :-)

Postby AtariZoll » Wed Sep 09, 2015 12:22 pm

Frank B wrote:Interesting. Is that using Doug's photochrome source and tech?


Yes, that video uses Photochrome for high-color. Later I went on Cyg's system because it is little better for video.


Considering that 3.5 MB/sec - that's maybe possible with RAM on that SCSI board, so Fast RAM. Surely not video RAM of Amiga.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Interesting discussion at YouTube :-)

Postby alexh » Wed Sep 09, 2015 12:52 pm

Who would have thought but Amiga dude Ralph Babel was reading this thread and sent me a PM :)

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Re: Interesting discussion at YouTube :-)

Postby Frank B » Wed Sep 09, 2015 12:59 pm

alexh wrote:Who would have thought but Amiga dude Ralph Babel was reading this thread and sent me a PM :)


Just means he has good taste in computers (Atari and Amiga) ;)

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Re: Interesting discussion at YouTube :-)

Postby calimero » Wed Sep 09, 2015 1:02 pm

not again dlfrsilver ... :(
alexh wrote:Who would have thought but Amiga dude Ralph Babel was reading this thread and sent me a PM :)

maybe he make Google event for "Ralph Babel" ;)

and what he say?

btw
even if you have SCSI adapter that can achieve 3,2MB/s on Amiga (to FastRAM),
what is max. transfer rate of FastRAM to ChipRAM on 7MHz Amiga?
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Re: Interesting discussion at YouTube :-)

Postby Frank B » Wed Sep 09, 2015 1:17 pm

If there are 48 palette entries per line the size of each frame would be
48 * 200 * 2 = 19,200 bytes for the palette
32000 bytes for the display?

Ie 51,200 bytes per frame on the ST. On the Amiga a ham 320*200 image would be 6 planes of 8000 bytes (48,000) with 32 bytes for a palette.
I wonder if it would look nice assuming the drive can keep up? Here's a youtube link. https://www.youtube.com/watch?v=Gf6erAxkW7Y No idea if it's ham or ham8

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Re: Interesting discussion at YouTube :-)

Postby alexh » Wed Sep 09, 2015 2:52 pm

calimero wrote:
alexh wrote:Who would have thought but Amiga dude Ralph Babel was reading this thread and sent me a PM :)

and what he say?


He corrected me on a few things (which I've fixed in my post) plus he wrote :

Ralph Babel wrote:OCS Chip RAM has a total bandwidth of 7 MB/s, and up to 4-color hires, the custom chips don't eat into the CPU/Zorro-II cycles, which leaves 3.5 MB/s. I don't know why A2091 maxes out at 1.9 MB/s and the GVP cards at 1.7 MB/s. Maybe some kind of arbitration/synchronization overhead.


calimero wrote:even if you have SCSI adapter that can achieve 3,2MB/s on Amiga (to FastRAM), what is max. transfer rate of FastRAM to ChipRAM on 7MHz Amiga?

I quoted the SCSI DMA->CHIP RAM speeds which were 1.7MB/s
Last edited by alexh on Wed Sep 09, 2015 2:55 pm, edited 2 times in total.

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Re: Interesting discussion at YouTube :-)

Postby calimero » Thu Sep 10, 2015 10:52 am

alexh wrote:
calimero wrote:even if you have SCSI adapter that can achieve 3,2MB/s on Amiga (to FastRAM), what is max. transfer rate of FastRAM to ChipRAM on 7MHz Amiga?

I quoted the SCSI DMA->CHIP RAM speeds which were 1.7MB/s

hm, I ask for speed betwen FastRAM and ChipRAM - if SCSI can have transfer up to 3,2MB/s to FastRAM (data from http://babel.de/amiga.html link), than you can load video data to FastRAM and than copy them to ChipRAM. If speed of ChipRAM is 7MB/s and you can achieve it while SCSI loading data to FastRAM than you could have faster transfer than loading data from SCSI DMA->CHIP RAM speeds which were 1.7MB/s
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Re: Interesting discussion at YouTube :-)

Postby dlfrsilver » Thu Sep 10, 2015 11:30 am

Frank B wrote:
alexh wrote:DFSilver is confused. 3.5MB/s is the theoretical maximum of the Zorro II bus the SCSI drive connects to. Drives cannot operate at that speed, especially when transferring to RAM which will be via arbitration.

Even with a special highly optimized driver called "GuruROM" the GVP SCSI Impact II can only do 1.7MB/s into chip memory (required for displaying video)

Don't believe me? Then here it is from the guy who invented the hardware and software.

http://babel.de/amiga.html


Yes. He will remain confused about the Amiga till he reads and understands the HRM. ;)
The DMA controller is a standard feature in the ST which is sadly missing on the Amiga. Still there's always IDE PIO mode 0. Slow as hell, CPU sucking but better than nothing. The GVP unit probably costs more than the ST too :)


The difference between the amiga and ST is the following :

The DMA chip in the ST is used for floppy drive AND hard drives. the DMA chip on amiga only take care of the floppy drive. That's why the HD+8 impact GVP II series use a SCSI to DMA western digital chip.

Then the 3,5MB/S is done with the INTERNAL fast-ram of the HD+8 impact GVP series II. This can't happen with chip-ram (i never said so !)

btw, i already told that in a previous topic here on atari forum, and yes the price of this hardware was superior to the one an STE (5990 francs at that time).

so don't misinterpret what i said. I'm happy Ralph Babel corrected a few things here and there.
Last edited by dlfrsilver on Thu Sep 10, 2015 11:36 am, edited 1 time in total.
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Re: Interesting discussion at YouTube :-)

Postby Frank B » Thu Sep 10, 2015 11:33 am

dlfrsilver wrote:so don't misinterpret what i said.


Which chip is the DMA chip on the Amiga? Can you list exactly what it is responsible for? Answers in the HRM btw.

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Re: Interesting discussion at YouTube :-)

Postby calimero » Thu Sep 10, 2015 11:36 am

dlfrsilver wrote:Then the 3,5MB/S is done with the INTERNAL fast-ram of the HD+8 impact GVP series II. This can't happen with chip-ram (i never said so !)

so don't misinterpret what i said.

but you need 3,5MB/s to ChipRAM to get video!
Otherwise data: "3,5MB/s" is utterly useless for any video playback talk.
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Re: Interesting discussion at YouTube :-)

Postby Frank B » Thu Sep 10, 2015 11:42 am

You get a bonus point if you can identify which architecture block handles decoding of DMA-ed drive data.

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Re: Interesting discussion at YouTube :-)

Postby dlfrsilver » Thu Sep 10, 2015 11:44 am

Frank B wrote:
dlfrsilver wrote:so don't misinterpret what i said.


Which chip is the DMA chip on the Amiga? Can you list exactly what it is responsible for? Answers in the HRM btw.


the amiga has has DMA channels splitted between Agnus (25), Paula (4) and the blitter (4).

It's not specifically tied in one chip but spanned over many of them. Paula take care of the floppy drive, so it does DMA yes :)

that's why there is a western digital SCSI to DMA chip onboard on the GVP II hard drive for A500.
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Re: Interesting discussion at YouTube :-)

Postby Frank B » Thu Sep 10, 2015 11:46 am

dlfrsilver wrote:
Frank B wrote:
dlfrsilver wrote:so don't misinterpret what i said.


Which chip is the DMA chip on the Amiga? Can you list exactly what it is responsible for? Answers in the HRM btw.


the amiga has has DMA channels splitted between Agnus (25), Paula (4) and the blitter (4).

It's not specifically tied in one chip but spanned over many of them. Paula take care of the floppy drive, so it does DMA yes :)

that's why there is a western digital SCSI to DMA chip onboard on the GVP II hard drive for A500.


Not quite. There is one chip responsible for DMA and 25 channels in total for OCS/ECS.

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Re: Interesting discussion at YouTube :-)

Postby dlfrsilver » Thu Sep 10, 2015 12:00 pm

It's the Agnus chip.
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Re: Interesting discussion at YouTube :-)

Postby Frank B » Thu Sep 10, 2015 3:00 pm

dlfrsilver wrote:It's the Agnus chip.


Correct. This also hosts the copper and the blitter. What about my other question? You might need to read the HRM to get an answer :D

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Re: Interesting discussion at YouTube :-)

Postby AtariZoll » Thu Sep 10, 2015 5:57 pm

calimero wrote:
dlfrsilver wrote:Then the 3,5MB/S is done with the INTERNAL fast-ram of the HD+8 impact GVP series II. This can't happen with chip-ram (i never said so !)

so don't misinterpret what i said.

but you need 3,5MB/s to ChipRAM to get video!
Otherwise data: "3,5MB/s" is utterly useless for any video playback talk.


Transferring from Fast RAM to Chip RAM while loading with high speed from disk could be max some 1.5 MB/sec . In other words, much slower than straight DMA access on Atari - here not talking about UltraSatan speed, what is approx. half of possible. But Amiga has here one big advantage: no need for huge CPU load when displaying hi-color. On the other side, if not using Atari DMA, then can load color data straight to shifter, without intermediate storing in RAM, or even CPU.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Interesting discussion at YouTube :-)

Postby Frank B » Thu Sep 10, 2015 8:26 pm

AtariZoll wrote:
calimero wrote:
dlfrsilver wrote:Then the 3,5MB/S is done with the INTERNAL fast-ram of the HD+8 impact GVP series II. This can't happen with chip-ram (i never said so !)

so don't misinterpret what i said.

but you need 3,5MB/s to ChipRAM to get video!
Otherwise data: "3,5MB/s" is utterly useless for any video playback talk.


Transferring from Fast RAM to Chip RAM while loading with high speed from disk could be max some 1.5 MB/sec . In other words, much slower than straight DMA access on Atari - here not talking about UltraSatan speed, what is approx. half of possible. But Amiga has here one big advantage: no need for huge CPU load when displaying hi-color. On the other side, if not using Atari DMA, then can load color data straight to shifter, without intermediate storing in RAM, or even CPU.


It should be possible to do photochrome like displays with the copper.

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Re: Interesting discussion at YouTube :-)

Postby dlfrsilver » Fri Sep 11, 2015 1:47 am

@Frank :

Two technical questions to you :

- Why is Denise faster than the Shifter ?

- Why the shifter is a choke point for the 68000 CPU on the ST ?

Thanks for your replies :)
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Re: Interesting discussion at YouTube :-)

Postby Frank B » Fri Sep 11, 2015 6:23 am

dlfrsilver wrote:@Frank :

Two technical questions to you :

- Why is Denise faster than the Shifter ?

- Why the shifter is a choke point for the 68000 CPU on the ST ?

Thanks for your replies :)



I've noticed you haven't answered my question about drive data encoding. I'll ask one more question. It's answer can also be found in the HRM.
How can the copper perform a loop to load a repeated palette every vertical line. This one should be easy but it's not all down to skip.
Seriously just read the reference manual. You'll enjoy it :)

1)

I don't think it's correct to say shifter is slower than OCS Denise. Denise however is capable of consuming odd and even "ticks" from agnus allowing for twice the bandwidth for displays. Ie 4 plane high res (640 non overscanned) displays. Note that on such a display the copper, blitter and CPU are blocked on the Amiga from doing anything in chip RAM when the display is active. Horizontal pixels on PAL displays for the ST are actually smaller than on the Amiga due to borders. What does that imply? ;) I think it's more accurate to say that Denise can use CPU cycles to do more at the expense of the CPU and rest of the chipset. Ie it can consume odd and even ticks (dma slots) for higher resolution displays or use more planes (6) in low res.

2)

Hmm choke point. More accurate a description for the DMA contention mentioned above! I believe you're referring to cycle rounding to 4 here.
It's worth noting that this also happens with CHIP ram accesses on the Amiga. Even with only 4 bitplanes active. It's the same technique in fact.
Fast RAM can speed the Amiga up even on 4 plane displays. Some instructions can execute without being divisible by 4. Ie shifts and branches IIRC.
Last edited by Frank B on Sat Sep 12, 2015 8:00 pm, edited 2 times in total.

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Re: Interesting discussion at YouTube :-)

Postby VivienSm » Fri Sep 11, 2015 8:49 am

Very nice underground life, which is beautiful.

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Re: Interesting discussion at YouTube :-)

Postby calimero » Fri Sep 11, 2015 10:56 am

dlfrsilver wrote:@Frank :

Two technical questions to you :

- Why is Denise faster than the Shifter ?

- Why the shifter is a choke point for the 68000 CPU on the ST ?

Thanks for your replies :)

and you did not replay how you can achieve 3.5MB/s transfer rate from harddisk to ChipRAM
which is necessary for high quality video playback like on Atari ST.


You blatantly say untrue on youtube comments claiming "3,5MB/s" ond 68000 Amiga:
"HD Impact GVP-II series hard drives for A500 from GVP are doing 3,5mb/s with SCSI with a regular 68000. It's faster than ultrasatan and any other hard drives i got my hands on for atari ST/E.
It's not theoric, it's the real deal."


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