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      /  Arne and Gunnars ASM course Twitch video
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PosterThread
Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 18-Aug-2021 18:18:10
#61 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@ppcamiga1

Quote:
Amiga 1200 would be much better if Commodore instead of AGA
use good old ECS and add in parallel new chips with chunky pixels etc.


But wouldn't that make it like EGA but crappier? Because I'm thinking 16 colours here. There wouldn't be enough bandwidth I think for anything better. 4-bit would fit in memory. 8-bit would be pushing it. So even with EGA hardware acceleration it would be good for 2 colour Workbench but not so much for games that had more before.

VGA? ECS was 4 bit RGB so no way could it match VGA. AGA surpasses the 6 bit VGA with full 24 bit colour CLUT.

What I think they should have done, is have a special mode that disabled the copper, bitplanes and instead read data directly from chip ram directly into the CLUT index register. A DDM, direct data mode. There was surely enough bandwidth, as a 32-bit copper code took up four pixels, so that's one byte per pixel. So 4 bit packed certainly would fit. 8 bit possibly with ECS. And definately on AGA , even 16 bit on AGA, since each code took 2 pixels hi speed. And it wouldn't have been beat by a Falcon.

Last edited by Hypex on 18-Aug-2021 at 06:19 PM.

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NutsAboutAmiga 
Re: Arne and Gunnars ASM course Twitch video
Posted on 18-Aug-2021 20:54:48
#62 ]
Elite Member
Joined: 9-Jun-2004
Posts: 11871
From: Norway

@Hypex

Copper is 16bit on aga as well, you need to do at least 4 copper commands to set one AGA color value, BPLCON3 bit 9 has to be enabled, to set the lower 4bits of 32b RGB values. 32bit copper might made it a lot more interesting, wont hurst if it was able to have its own registers, and do subtraction, addition and multiplications as well.

Major upgraded cooper might done texture mapping, shading, and all kinds of interesting stuff, who know maybe even expanded into 3D.

Last edited by NutsAboutAmiga on 18-Aug-2021 at 09:12 PM.
Last edited by NutsAboutAmiga on 18-Aug-2021 at 09:12 PM.
Last edited by NutsAboutAmiga on 18-Aug-2021 at 09:11 PM.
Last edited by NutsAboutAmiga on 18-Aug-2021 at 08:58 PM.
Last edited by NutsAboutAmiga on 18-Aug-2021 at 08:56 PM.

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bison 
Re: Arne and Gunnars ASM course Twitch video
Posted on 18-Aug-2021 21:06:39
#63 ]
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Joined: 18-Dec-2007
Posts: 1874
From: N-Space

@Hypex

The premise "add in parallel new chips with chunky pixels" leaves it pretty wide-open. Even if this hypothetical chip set couldn't access the rest of the Amiga custom chips or RAM, it could still get 320x200 in 256 colors with 64K dedicated RAM. I'm imaging this as something like MCGA slapped onto an Amiga.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 19-Aug-2021 7:03:45
#64 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@NutsAboutAmiga

Copper is 16 bit based like entire chipset design but a full instruction is always 32 bits. It's 16 bit opcode with 16 bit operand. The Copper is more RISC than RISC itself!

So the copper instruction decoder needs two 16 bit cycles before it can execute it. 32 bit operands could have reduced data payload, and the Vampire has this, but it only helps with pointers. It wouldn't help with hi and lo nibbles like AGA 24 bit RGB is organised. So, it may have been better if the copper worked more like PPC 32-bit split write, by being able to write the hi nibbles then low nibbles of a 32 bit value. Though the encoding provided very little space, only a few bits, for move wait and the rarely used skip so hard to expand it.

But, the copper was limited by needing to set bank switching, since it can only write to chipset and they didn't add any more colour registers which restricted it. Thus, to set a 32 bit value with 24 bit RGB into a colour register, requires four 16 bit write instructions in a row. Alternatively, the high could be all set, then the lo. Or any sequence between bank switching of nibbles and palette windows to reduce writes as much as possible.

The copper could do basic 3d by sliding lines and was made for shading which which was used for great effect. And could switch pre rendered bitmaps per line for advanced use. But beyond that is beyond the scope of the copper. For things like texture mapping needed by 3d there needs to be bitmap scaling and warping. That is the blitters job. The OS already had a bitmap scaler but it needed to divide the operation into different blits or use CPU when needed. The blitter needed upgrading to do it. The blitter already supported line drawing and drawing with textures. Both of these needed expanding so it could warp from one shape to another. As well as doing it on multiple bitplanes at once. But packed data was easier to deal with.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 19-Aug-2021 7:12:27
#65 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@bison

Because ppcamiga1 used ECS as a base I purposelessly restricted it to ECS levels. Yes, obviously an intention would be low res in 8 bit depth with 24 bit palette. But, ECS only has 6 bit depth max, with 4 bit RGB. Anything over 16 colours like 32 or 64 would need 8 bits packed. So, to be practical and realistic to ECS, I only see this as being chunky low res up to 64 colours, or chunky hi res up to 16 colours. Both on RGB4. And both short of VGA. Except for a chunky HAM.

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NutsAboutAmiga 
Re: Arne and Gunnars ASM course Twitch video
Posted on 19-Aug-2021 16:47:01
#66 ]
Elite Member
Joined: 9-Jun-2004
Posts: 11871
From: Norway

@Hypex

You have point, about fixed length instruction vs non fixed length instructions,

if one opcode had possibility 1 or 2 operands, you can load it in "3 clock cycles" + memory latency. going to fixed 32bit you load upper and lower bit in 1 opcode, but you need two 32bit operation at least, if copper was modified, as following, OCS/ECS colors are 12bit that leaves 4 bit free to use as you like, as move does mess with 0bit of 2en 16bit, and we don’t have alpha color values, so this 4bits are unused, so instead of using a hardware register BPLCON3 bit 9, it can encoded it in the color instead, saving 2 instructions, and you only need "2 clock cycles" + memory latency..

Last edited by NutsAboutAmiga on 19-Aug-2021 at 05:01 PM.
Last edited by NutsAboutAmiga on 19-Aug-2021 at 04:59 PM.
Last edited by NutsAboutAmiga on 19-Aug-2021 at 04:53 PM.
Last edited by NutsAboutAmiga on 19-Aug-2021 at 04:48 PM.

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ppcamiga1 
Re: Arne and Gunnars ASM course Twitch video
Posted on 19-Aug-2021 18:30:54
#67 ]
Regular Member
Joined: 23-Aug-2015
Posts: 269
From: Unknown

@Hypex

It may be anything.
Just good old ECS on top for compatybility and decent (1992) graphics.
Mixed video signals.

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matthey 
Re: Arne and Gunnars ASM course Twitch video
Posted on 19-Aug-2021 18:42:44
#68 ]
Super Member
Joined: 14-Mar-2007
Posts: 1145
From: Kansas

bison Quote:

The premise "add in parallel new chips with chunky pixels" leaves it pretty wide-open. Even if this hypothetical chip set couldn't access the rest of the Amiga custom chips or RAM, it could still get 320x200 in 256 colors with 64K dedicated RAM. I'm imaging this as something like MCGA slapped onto an Amiga.


With chunky, parallel blitters are unnecessary. If there was enough chip memory bandwidth for 320x200x8 using 64kiB, then VRAM (like Jay wanted for Ranger) would have doubled the bandwidth allowing for 320x200x16 using 128kiB (256kiB for double buffering) without the CLUT. Full 16 bit chunky R5G6B5 or A1R5G5B5 would have allowed a larger palette of colors than ECS and more colors than AGA without HAM8. With 2MiB of chip memory, 640x480x16 double buffered would have been possible. With just chip memory size increases, this should have kept the Amiga viable until 3D was added and adding 3D would have been easier with chunky.

NutsAboutAmiga Quote:

You have point, about fixed length instruction vs non fixed length instructions,

if one opcode had possibility 1 or 2 operands, you can load it in "3 clock cycles" + memory latency. going to fixed 32bit you load upper and lower bit in 1 opcode, but you need two 32bit operation at least, if copper was modified, as following, OCS/ECS colors are 12bit that leaves 4 bit free to use as you like, as move does mess with 0bit of 2en 16bit, and we don’t have alpha color values, so this 4bits are unused, so instead of using a hardware register BPLCON3 bit 9, it can encoded it in the color instead, saving 2 instructions, and you only need "2 clock cycles" + memory latency..


With a variable length encoding, multiple instructions are usually fetched into an instruction buffer where they are examined. Additional clock cycles per instruction extension to fetch the code are unnecessary if the fetch width is wider than the maximum instruction length (fetch at least 8 bytes per cycle for a copper supporting a 4 byte displacement). Padding 6 byte instructions to 8 bytes for better alignment simplifies examination at the cost of code density.

Last edited by matthey on 19-Aug-2021 at 06:46 PM.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 21-Aug-2021 15:29:33
#69 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@NutsAboutAmiga

Being specific to $DFF000 does give some headroom as it would have used $DFF000 as a base reference. As well as the actual chipset range only using up to $200. So that would allow for extra coding for extra functions.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 21-Aug-2021 15:30:35
#70 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@ppcamiga1

Almost sounds like an Amiga with a graphic card.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 21-Aug-2021 15:56:40
#71 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@matthey

Quote:
Full 16 bit chunky R5G6B5 or A1R5G5B5 would have allowed a larger palette of colors than ECS and more colors than AGA without HAM8


The only issue is that managing a 15 or 16 bit RGB framebuffer is more computationally expensive than a CLUT. A CLUT lets you use tricks like colour cycling and on the Amiga changing colours on scan lines with a copper list. You lose that luxury with direct RGB and it's best to compensate with some other hardware acceleration.

As an example, the OS3,9 installer, was inefficient and not coded for real Amiga chipset. It had a gradient background that was drawn manually and it could be seen drawing down the screen. Acceptable with a graphic card though it really needs some line blitting to assist. But on Amiga hardware with a copper it should have known better and used the hardware.

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ppcamiga1 
Re: Arne and Gunnars ASM course Twitch video
Posted on 22-Aug-2021 9:10:20
#72 ]
Regular Member
Joined: 23-Aug-2015
Posts: 269
From: Unknown

@Hypex

Yes. Amiga with ECS and graphics card is my dream Amiga.

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NutsAboutAmiga 
Re: Arne and Gunnars ASM course Twitch video
Posted on 22-Aug-2021 10:15:46
#73 ]
Elite Member
Joined: 9-Jun-2004
Posts: 11871
From: Norway

@Hypex

Quote:
A CLUT lets you use tricks like color cycling


pretty much any Macintosh, ATARI and PC can do, also chunky 2 color, 4 colors & 16 colors, is also pretty standard at least on Macintosh and ATARI.

Quote:
Amiga changing colours on scan lines with a copper list.


Something you only need to do because you have too few colors in your palette.

Quote:
As an example, the OS3,9 installer, was inefficient and not coded for real Amiga chipset. It had a gradient background that was drawn manually and it could be seen drawing down the screen. Acceptable with a graphic card though it really needs some line blitting to assist. But on Amiga hardware with a copper, it should have known better and used the hardware.


Yes because copper was not part of the picture format, instead you get a color reduced version using dithering, of course this is an none issue on 15bit/16bit/32bit graphics.
If graphic on graphic card was used for graphics,(not emulating fast memory as some graphics drivers do on the Amiga did) you might had the background bitmap stored in the same memory as background screen, and use GPU to copy graphics, instead to using CPU write to the memory, hardware acceleration in GPU’s was introduced a long time ago. Composition is a huge advantage for modern graphic cards.

https://en.wikipedia.org/wiki/Graphics_processing_unit#1990s
https://en.wikipedia.org/wiki/DirectDraw

Last edited by NutsAboutAmiga on 22-Aug-2021 at 10:17 AM.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 23-Aug-2021 15:02:21
#74 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@ppcamiga1

A Vampire can also act as a graphic card for a ECS Amiga.

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Hypex 
Re: Arne and Gunnars ASM course Twitch video
Posted on 26-Aug-2021 17:06:54
#75 ]
Elite Member
Joined: 6-May-2007
Posts: 10264
From: Greensborough, Australia

@NutsAboutAmiga

Quote:
pretty much any Macintosh, ATARI and PC can do, also chunky 2 color, 4 colors & 16 colors, is also pretty standard at least on Macintosh and ATARI.


Well doing it in 2 or 4 colours is useless as there isn't enough colour space to do shading. Even ANSI 16 colours are really a light and dark 8 colour palette. A C64 can do it with mostly three shades. A C16 whips that with 8 shades a colour in a palette range of almost 7 bit resolution. The Amiga could define palette colours so no problem there making use of it. And after that VGA had enough colours to also do it.

Quote:
Something you only need to do because you have too few colors in your palette.


It's actually better this way. You only need to change one colour and can have it change on screen as well. Where as if there was only the CLUT to rely on then it would need to be drawn across the screen as well which is more work. Sure, a blitter could draw lines and fill in areas. But the copper is more efficient, like having sprites, as it gives you a free lunch. You change one register and then the video hardware does it for you live in real time!

Quote:
Yes because copper was not part of the picture format, instead you get a color reduced version using dithering, of course this is an none issue on 15bit/16bit/32bit graphics.


It doesn't matter about picture formats. It's setting a gradient in the background. A program to install the OS should know how to program the hardware. They were just being lazy. All the talk about using the OS to display Amiga graphics were made useless, because the OS can certainly bring up a copper list with ease, but the OS installer didn't even demonstrate it.

Last edited by Hypex on 27-Aug-2021 at 11:08 AM.

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