Click Here
home features news forums classifieds faqs links search
6053 members 
Amiga Q&A /  Free for All /  Emulation /  Gaming / (Latest Posts)
Login

Nickname

Password

Lost Password?

Don't have an account yet?
Register now!

Support Amigaworld.net
Your support is needed and is appreciated as Amigaworld.net is primarily dependent upon the support of its users.
Donate

Menu
Main sections
» Home
» Features
» News
» Forums
» Classifieds
» Links
» Downloads
Extras
» OS4 Zone
» IRC Network
» AmigaWorld Radio
» Newsfeed
» Top Members
» Amiga Dealers
Information
» About Us
» FAQs
» Advertise
» Polls
» Terms of Service
» Search

IRC Channel
Server: irc.amigaworld.net
Ports: 1024,5555, 6665-6669
SSL port: 6697
Channel: #Amigaworld
Channel Policy and Guidelines

Who's Online
13 crawler(s) on-line.
 17 guest(s) on-line.
 1 member(s) on-line.


 Rob

You are an anonymous user.
Register Now!
 Rob:  1 min ago
 kolla:  6 mins ago
 Torque:  11 mins ago
 VooDoo:  13 mins ago
 zipper:  19 mins ago
 amigakit:  29 mins ago
 hotrod:  45 mins ago
 amigagr:  52 mins ago
 Karlos:  1 hr 4 mins ago
 Bosanac:  1 hr 38 mins ago

/  Forum Index
   /  Amiga General Chat
      /  Port AmigaOS 4 to x86
Register To Post

Goto page ( Previous Page 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 )
PosterThread
MEGA_RJ_MICAL 
Re: Port AmigaOS 4 to x86
Posted on 28-Jul-2022 23:33:22
#341 ]
Cult Member
Joined: 13-Dec-2019
Posts: 959
From: AMIGAWORLD.NET WAS ORIGINALLY FOUNDED BY DAVID DOYLE

ZORRAM

_________________
I HAVE ABS OF STEEL
--
CAN YOU SEE ME? CAN YOU HEAR ME? OK FOR WORK

 Status: Offline
Profile     Report this post  
bhabbott 
Re: Port AmigaOS 4 to x86
Posted on 29-Jul-2022 14:33:30
#342 ]
Regular Member
Joined: 6-Jun-2018
Posts: 142
From: Aotearoa

@Hammer

Quote:

Hammer wrote:

68020's instruction per clock is similar to 68030, 68020 @ 25Mhz overclocked to 28 Mhz would be sufficient for SNES-SuperFX-2 Doom port with the missing ceiling and floor textures.

The recent Dread game is missing ceiling and floor textures.

Dread is highly optimized to get sufficient speed on a 7MHz 68000. It uses a method of texture mapping that distorts the perspective and has vertical lines when close up (I hope they fix this in the release version). Much effort has been put into making the low resolution textures look good, and using sprites for the weapons etc. to increase resolution where you can without the game slowing to a crawl. This is hardcore Amiga game development at its best, showing what can be done when you match rendering techniques to the machine's hardware features.

Today we have the luxury of being able to do stuff like this, but in 1993 even if you had all the source code to Dread you still wouldn't be able make a respectable Doom port with it. You would have to redo all the textures, rewrite large parts of the original Doom code, and put up with a lot of compromises like they did with the SNES version - which sucked. All that would do (assuming you could pull it off) is prove what everybody was saying - that the Amiga (A500/1200) wasn't powerful enough to do 3D games properly.

Quote:
Gloom didn't capture the "Doom feel" when compared to Dread.

Dread isn't Doom and it has a quite different 'feel'. But you are right about Gloom, which suffered the same faults as most other Amiga 3D games - boring unimaginative level design and repetitive gameplay that doesn't draw you into the game. It is this content that makes the difference between a so-so game and a great one (having a technically competent game engine is just the first step).

Quote:
In 1993, Amiga 4000/040's asking price was about Pentium PC level, hence Amiga 4000 didn't price competitive.

Demonstrably not true. Here are some US prices from 1993:-

AmigaWorld March 1993:-
A1200 $399
A4000/030 $1599
A4000/040 $2299

PC World March 1993, "Marketplace" monthly price survey of 'popular' PCs:-
Compaq Deskpro 386DX-33 4MB RAM $1979
Compaq Deskpro 486SX-25 4MB RAM $2569
Dell System 425SE 486SX-25 4MB RAM $3100
IBM PS/2 Valuepoint 486DX-33 8MB RAM $2199
(these are base models without monitor, sound card etc.)

Guess what's missing from this list? That's right, no Pentium PCs - because there weren't any.

So when the A4000 was released its price was competitive with name-brand PCs with similar specs. But price wasn't the issue. Nobody was comparing a Compaq Deskpro to an Amiga 4000 and thinking "Why go the PC way when I could get an Amiga 4000 instead and save $270!". The A4000 could have been cheaper than even the crappiest clone and few people would have bought one - because it wasn't IBM compatible.

The ironical thing about these prices is that today 486 PCs only command a few hundred dollars at best, while A4000s go for well over US$1000. Seems the Amiga has held its value much better...

Quote:
A4000 has a motherboard + daughter board with slots while the 486 PC competition has a single motherboard with slots.

Not sure what the relevance of this is, but many desktop PCs also had daughter boards (AKA 'riser cards') to reduce the case height. I have a 386SX motherboard with one.

 Status: Offline
Profile     Report this post  
matthey 
Re: Port AmigaOS 4 to x86
Posted on 29-Jul-2022 23:09:32
#343 ]
Super Member
Joined: 14-Mar-2007
Posts: 1577
From: Kansas

Hammer Quote:
In 1993, Amiga 4000/040's asking price was about Pentium PC level, hence Amiga 4000 didn't price competitive.


bhabbott Quote:

Demonstrably not true. Here are some US prices from 1993:-

AmigaWorld March 1993:-
A1200 $399
A4000/030 $1599
A4000/040 $2299

PC World March 1993, "Marketplace" monthly price survey of 'popular' PCs:-
Compaq Deskpro 386DX-33 4MB RAM $1979
Compaq Deskpro 486SX-25 4MB RAM $2569
Dell System 425SE 486SX-25 4MB RAM $3100
IBM PS/2 Valuepoint 486DX-33 8MB RAM $2199
(these are base models without monitor, sound card etc.)

Guess what's missing from this list? That's right, no Pentium PCs - because there weren't any.


The Pentium was launched in march of 1993 and was practically unavailable for a short time but was advertised and available later in the year like Hammer posted. They were expensive at first with a system likely costing $3000 and up but that was a Pentium@60MHz often with a hard drive and 8MiB of memory which had good value. Lower end systems dropped in price and Intel was forced to remain competitive with pricing because of AMD and Cyrix competition on the way.

bhabbott Quote:

So when the A4000 was released its price was competitive with name-brand PCs with similar specs. But price wasn't the issue. Nobody was comparing a Compaq Deskpro to an Amiga 4000 and thinking "Why go the PC way when I could get an Amiga 4000 instead and save $270!". The A4000 could have been cheaper than even the crappiest clone and few people would have bought one - because it wasn't IBM compatible.


The Amiga was a different market and the PC market in general had a software advantage. I don't think the less popular 68k CPU was the big limitation as the Apple 68040 Macs gained in popularity and had the largest percentage of the desktop market ever before declining with PPC Macs. The 68040 Mac platform in 1993-1995 gained gaming market share and received FPS shooters like Doom (1994), Marathon (1994) and Star Wars: Dark Forces (1995) which ran on the 68040. The Amiga gaming market share was declining during this same period despite previously being superior for games. I don't think the problem was lack of chunky support either. I think it had more to do with CBM offering the cheapest possible hardware with slowest possible clock speeds, cheapest slowest memory, cheapest slowest hard drives, etc. even for the high end. Macs cost more but the average 68040 Mac was soon outperforming the average 68040 Amiga and few Amiga users even upgraded to a 68040 or higher. There weren't enough 68040 Amiga users to port games like Doom to the Amiga and most of the 68040 Amigas were CBM hardware 68040@25MHz with no local fast memory and PIO IDE drives stealing CPU time. The Amiga 4000 was a good example of the value and quality deterioration of the Amiga platform.

Last edited by matthey on 29-Jul-2022 at 11:10 PM.

 Status: Offline
Profile     Report this post  
BigD 
Re: Port AmigaOS 4 to x86
Posted on 29-Jul-2022 23:57:57
#344 ]
Elite Member
Joined: 11-Aug-2005
Posts: 6472
From: UK

@matthey

Admittedly the C= 68040 boards were baffling with very little thought given to the onboard ram performance boost which was a game changer! Phase5 were running rings round C= designs by the end! The 060 based A4000T used a QuikPak designed EDO Ram equipped board but it is doubtful C= would have done as well if they 'd have survived! Shocking!

_________________
"Art challenges technology. Technology inspires the art."
John Lasseter, Co-Founder of Pixar Animation Studios

 Status: Offline
Profile     Report this post  
Hammer 
Re: Port AmigaOS 4 to x86
Posted on 31-Jul-2022 2:31:28
#345 ]
Elite Member
Joined: 9-Mar-2003
Posts: 4409
From: Australia

@bhabbott

Quote:

Dread is highly optimized to get sufficient speed on a 7MHz 68000. It uses a method of texture mapping that distorts the perspective and has vertical lines when close up (I hope they fix this in the release version). Much effort has been put into making the low resolution textures look good, and using sprites for the weapons etc. to increase resolution where you can without the game slowing to a crawl. This is hardcore Amiga game development at its best, showing what can be done when you match rendering techniques to the machine's hardware features.

Dread's vertical lines are akin to resource conservation techniques such as pixel reconstruction in modern console games. IF Hollywood accepts pixel reconstruction tricks, then it's good enough for games.

It's mostly PC Master Race demanded "uncompressed pixels".

Quote:

Today we have the luxury of being able to do stuff like this, but in 1993 even if you had all the source code to Dread you still wouldn't be able make a respectable Doom port with it. You would have to redo all the textures, rewrite large parts of the original Doom code, and put up with a lot of compromises like they did with the SNES version - which sucked. All that would do (assuming you could pull it off) is prove what everybody was saying - that the Amiga (A500/1200) wasn't powerful enough to do 3D games properly.


Dread's redo textures are similar to The Bitmap Brothers' Gods or Xenon II Mega-Blast's 16-color artwork since Atari ST has a 16-color limitation.

Somebody with Dread's 3D engine has recycled God's artwork style and it looks pretty good.

Dread's color palette selection theory has existed in the past.


Quote:

Demonstrably not true. Here are some US prices from 1993:-


AmigaWorld March 1993:-
A1200 $399
A4000/030 $1599
A4000/040 $2299

PC World March 1993, "Marketplace" monthly price survey of 'popular' PCs:-
Compaq Deskpro 386DX-33 4MB RAM $1979
Compaq Deskpro 486SX-25 4MB RAM $2569
Dell System 425SE 486SX-25 4MB RAM $3100
IBM PS/2 Valuepoint 486DX-33 8MB RAM $2199
(these are base models without monitor, sound card etc.)

That's demonstrably not true.

Reminder, Doom doesn't use the FPU, hence 486DX's FPU is not used. A fast 68LC040 would be needed.

Doom was released on the 10th of December 1993.

https://vintageapple.org/pcworld/pdf/PC_World_9306_June_1993.pdf
Gateway Party List, Page 72 of 314

4SX-33 with 486-SX 33Mhz, 4MB RAM, 170 MB HDD, Windows Video accelerator 1MB video DRAM, 14-inch monitor for $1494,

4DX-33 with 486-DX 33Mhz, 8MB RAM, 212 MB HDD, Windows Video accelerator 1MB video DRAM, 14-inch monitor for $1895,

Page 128 of 314
Polywell Poly 486-33V with 486SX-33, 4MB of RAM, SVGA 1MB VL-Bus, price: $1250


https://vintageapple.org/pcworld/pdf/PC_World_9308_August_1993.pdf
Gateway Party List, Page 62 of 324

4SX-33 with 486-SX 33Mhz, 4MB RAM, 212MB HDD, Windows Video accelerator 1MB video DRAM, 14-inch monitor for $1495,

4DX-33 with 486-DX 33Mhz, 8MB RAM, 212 MB HDD, Windows Video accelerator 1MB video DRAM, 14-inch monitor for $1795,

Remember Gateway?

Page 45 of 324
From DELL
Dell Dimension 486SX 33Mhz, 4MB RAM, 230 MB HDD, VLB SVGA card with 512 KB, 14-inch monitor for $1749,

Dell Dimension 486SX 25Mhz, 4MB RAM, 170MB HDD, VLB SVGA card with 512 KB, 14-inch monitor for $1749,

MS-DOS 6.0/Windows 3.1/Mouse included.



Page 292 of 324
From Comtrade
VESA Local Bus WinMax with 32-Bit VL-Bus Video Accelerator 1MB, 486DX2 66 Mhz, 210 MB HDD, 4MB RAM, Price: $1795



https://vintageapple.org/pcworld/pdf/PC_World_9310_October_1993.pdf
October 1993, Page 13 of 354,
ALR Inc, Model 1 has Pentium 60-based PC for $2495.



https://archive.org/details/amiga-world-1993-10/page/n7/mode/2up
Amigaworld, October 1993, Page 66 of 104
Amiga 4000/040 @ 25Mhz for $2299

Amiga 4000/030 @ 25Mhz for $1599



Page 82 of 104
M1230X's 68030 @ 50Mhz has $349
1942 Monitor has $389
A1200 with 85MB HDD has $624
A1200 with 130MB HDD has $724
2.5 inch HDD



Page 92 of 104
A1200, $399
A1200 with 40MB HDD, $545
A1200 with 85MB HDD, $649
A1200 with 128MB HDD, $729

GVP 1230 with 68030 40Mhz with 4MB RAM, $579

Conner 40MB HD, $139.95
Conner 64MB HD, $229.95
Seagate 85MB HD, $239.95
Seagate 127MB HD, $315.00
Maxtor 128MB HD, $315.00


Page 70 of 104
A1200 with 120 MB HDD for $329
A1200 with 200 MB HDD for $429
MBX 1230 with 68030 @ 40 Mhz, off-chip FPU @ 33Mhz, with 4MB RAM , $549

The Commodore solution is beaten by the Gateway solution.

The A1200 SKUs have no "out-of-the-box" SKU targeting Doom.


Target sales period: XMas of 1993 Q4.. 1993 XMas sales period was Commodore's last chance.


I halted any further hardware investments on the Amiga platform in 1993 until the COVID-19 year 2020 A1200 Rev 1D1, Amikit 8MB RAM with FPU, and A500's Witcher 508 purchases. TF1260 in the year 2021 and A500's Pi-storm/Pi-3A in the year 2022.


In the end, IBM exited the PC clone business.

My Dad's 386DX+ET4000 PC and my Pentium 150 PC clones are local white box builds.
My Pentium 150 PC clone has a PCchips (Elitegroup Computer Systems Co., Ltd) motherboard.
The pattern continued to my current gaming PCs which have ASUS motherboards, NOT from Dell, HP, Lenovo and 'etc'.


My Dad's PS/2 Model 55SX was from government work and a decommissioned surplus that was replaced in 1992 by 386DX-33 +ET4000 PC. 386DX-33 +ET4000 PC was enough until 1996's Quake.


I have a 1.5-year-old Lenovo laptop with Ryzen 7 Pro 4750U.


You're in dreamland and refuse to see why Commodore's big box Amigas was uncompetitive!





Last edited by Hammer on 31-Jul-2022 at 03:38 AM.
Last edited by Hammer on 31-Jul-2022 at 03:35 AM.
Last edited by Hammer on 31-Jul-2022 at 03:34 AM.
Last edited by Hammer on 31-Jul-2022 at 03:31 AM.
Last edited by Hammer on 31-Jul-2022 at 03:20 AM.
Last edited by Hammer on 31-Jul-2022 at 03:13 AM.
Last edited by Hammer on 31-Jul-2022 at 03:01 AM.
Last edited by Hammer on 31-Jul-2022 at 02:55 AM.
Last edited by Hammer on 31-Jul-2022 at 02:47 AM.
Last edited by Hammer on 31-Jul-2022 at 02:42 AM.
Last edited by Hammer on 31-Jul-2022 at 02:40 AM.
Last edited by Hammer on 31-Jul-2022 at 02:39 AM.

_________________
Ryzen 7 5800X, DDR4-3600 64 GB RAM, GeForce RTX 3080 Ti
Ryzen 9 3900X, DDR4-3200 32 GB RAM, GeForce RTX 3080 Ti
Amiga 1200 (rev 1D1, KS 3.2, TF1260, 68060 @ 63 Mhz, 128 MB)
Amiga 500 (rev 6A, KS 3.2, PiStorm/RPi3a/Emu68)

 Status: Offline
Profile     Report this post  
kolla 
Re: Port AmigaOS 4 to x86
Posted on 31-Jul-2022 3:07:04
#346 ]
Elite Member
Joined: 21-Aug-2003
Posts: 2200
From: Trondheim, Norway

@Hammer

Big box Amiga and PCs in early 90s rarely even were in the same competition. Big box Amigas were used for specific tasks, like video toaster or SCALA infochannel systems, and other TV/multimedia tasks. They didn’t just dominate in that area, for quite some time, they were the only option.

_________________
B5D6A1D019D5D45BCC56F4782AC220D8B3E2A6CC

 Status: Offline
Profile     Report this post  
Hammer 
Re: Port AmigaOS 4 to x86
Posted on 31-Jul-2022 3:21:56
#347 ]
Elite Member
Joined: 9-Mar-2003
Posts: 4409
From: Australia

@kolla

Quote:

kolla wrote:
@Hammer

Big box Amiga and PCs in early 90s rarely even were in the same competition. Big box Amigas were used for specific tasks, like video toaster or SCALA infochannel systems, and other TV/multimedia tasks. They didn’t just dominate in that area, for quite some time, they were the only option.

Reminder, PC's Doom-type games wreaked Amiga's gaming scene.

Business PCs subsidized gaming/home PCs while gaming/home PCs subsidized business/workstation PCs i.e. PC's economy of scale murdered the Amiga.

Commodore couldn't survive on just Amiga 4000 with Video Toaster/SCALA business.

SGI learns a similar lesson they were smashed by a certain PC gaming GPU company i.e. NVIDIA.

Last edited by Hammer on 31-Jul-2022 at 03:35 PM.
Last edited by Hammer on 31-Jul-2022 at 03:43 AM.

_________________
Ryzen 7 5800X, DDR4-3600 64 GB RAM, GeForce RTX 3080 Ti
Ryzen 9 3900X, DDR4-3200 32 GB RAM, GeForce RTX 3080 Ti
Amiga 1200 (rev 1D1, KS 3.2, TF1260, 68060 @ 63 Mhz, 128 MB)
Amiga 500 (rev 6A, KS 3.2, PiStorm/RPi3a/Emu68)

 Status: Offline
Profile     Report this post  
cdimauro 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 9:33:58
#348 ]
Elite Member
Joined: 29-Oct-2012
Posts: 2689
From: Germany

@bhabbott

Quote:

bhabbott wrote:
@Hypex

Quote:

Hypex wrote:
@bhabbott

The Workbench screen was 2 bits depth so window layers had to be bliited twice per place.

Yes, but the amount blitted is about the same whether packed or planar.

Depends on the involved areas for the blit, but packed is the best / more efficient on bit-blitting operations.
Quote:
Small blits are less efficient, but inherently fast so it doesn't matter.

You've to setup the Blitter twice, but only once on a packed system.
Quote:
Quote:
Yes, my first Amiga was an A500 with Enhancer package and FastFonts. I can imagine why it was faster. It was likely almost as many writes setting up the blitter as it was actually writing it to the bitmap. The blitter was useful for large blocks at random locations but strings would be written letter by letter.

To be fair, other machines of the time like the PC also had very slow text rendering when going through the BIOS one character at a time. At least on the Amiga you could render a whole line at once,

This is all about the APIs which the specific platform is giving to developers.

Nobody stops you to implement your own version, that could be faster.
Quote:
and the blitter worked in parallel with the CPU so it could be doing other stuff at the same time.

Not always. With games, for example, the CPU was busy-polling the Blitter status register to see if the blit operation was completed and starting a new one. Plus, usually the Blitter had priority over the CPU, which means that the latter had no cycles available to access memory and so it was left in a frozen status.

BTW, some PCs had also a Blitter or coprocessor (and going truly in parallel with the CPU, since they worked on their own memory).
Quote:
What does this prove? For true 3D games - which the Amiga was supposed to be no good for because it didn't have chunky graphics - you need both a fast CPU and fast graphics bus for best performance. The overhead of converting chunky to planar is only an issue on slower machines, which aren't fast enough for this kind of game anyway.

Which, nevertheless, requires some time on faster machines, anyway.
Quote:
So all the talk of Commodore making the wrong choice in graphics architecture is off the mark.

That's wrong (see the packed vs planar thread) and it's also Red Herring. You're very inclined to logical fallacies and that is strange since you're supposed to be a developer, and developers should be familiar with logic...
Quote:
Using bitplanes made the hardware easier to implement,

Wrong again: see the other thread.
Quote:
minimized precious RAM usage,

Wrong again.
Quote:
and worked well with the relatively slow 68000 in earlier Amigas.

They could have worked better with packed graphics.
Quote:
Many fans also fault AGA for sticking with bitplanes, but it was a logical extension to OCS

And it was its problem: planar graphic issues becomes much worse with increased data bus sizes...
Quote:
which was also easy to implement,

Wrong again: it's easy only for masking operations.
Quote:
maintained good compatibility and didn't require major changes to the OS.

Well, the o.s. required several changes for AGA. Which, BTW, was an horrible patch over ECS.
Quote:
And where it really mattered (texture mapped 3D games) it wasn't the real bottleneck.

It was, as numbers proved: Amiga without graphic cards had the C2P cost to sustain, even on faster CPUs (and memories).

It's clear that you lived on a parallel universe...
Quote:
Quote:
My Pentium 150 with S3 Trio 64-based PC has smooth Quake 1 frame rates.

Using 1989-era ET4000AX improves the situation.

The ET4000AX was an exceptional ISA bus VGA card. Most PC clones of that era came with cheap cards such as the Trident TVGA (bad) or OAK OTIVGA (worse). This rarely if ever gets mentioned by fans comparing the Amiga to contemporary PCs.

At least they had the chance to buy one. On 1989. Which is NOT contemporary, right?

Which chance have you had at the time for Amigas?

BTW, you're the one which continuously mixed technologies and time periods. Only to favor your beloved Amiga, like the blind fanatic that you are.


@Hammer

Quote:

Hammer wrote:

For a dumb frame buffer, AGA is superior when compared to IBM VGA.

Is it fair? IBM VGA was available on 1987. AGA on... 1992!
Quote:
AGA can play full-motion videos @ 320x200 HAM8 (8 bits data) resolution.

If you just do it.
Quote:
As long the CPU is fast enough to generate procedural full-motion videos (aka 3D games), AGA can play these games at a reasonable frame rate.

You need a very fast CPU, which was quite expensive at the time. And... unavailable: on 1992 you only had a 25Mhz 68040 (AFAIR the 33Mhz version came later).

Whereas on PCs of the same time it was much easier: no C2P needed and much faster graphic cards available (at lower price). So, you didn't required a monster CPU only to overcome the planar graphics issues.
Quote:
Amiga 500 already has the hardware for C2P i.e. use the hardware Blitter.

This wasted bandwidth, since you had to read & combine multiple times the framebuffer with the single bitplanes.
Quote:
For Amiga 500, Dread C2P uses the hardware Blitter to lessen the workload for the CPU.

Dread is very nice achievement for the hardware. Nevertheless, it shows that the Amiga hardware was very limited for those kind of games.

In fact, the game completely lucks floor and ceiling. Only the sky is visible sometimes, with blocky graphics. Only the walls are rendered, with blocky and doughy graphics, with limited colors.. Graphics (texture) is almost always the same, with very low resolution. Similar things for characters: a few of them, which look pre-scaled, zoomed at fixed sizes. And the graphic is rendered at around 3-4 FPS (around 8 for the Amiga 1200).

This has nothing to do with Doom.
Quote:
Reminder, PC's Doom-type games wreaked Amiga's gaming scene.

The PC game market was already bigger than the Amiga one before Doom. You can take a look at the list of PC games release before Doom, and you can see yourself.

The game changer for PCs was represented by the introduction of VGA: from there on, PCs got much more attention and support, because users had the chance to see very colorful games available for their "business computers".

The other game changer was Windows 3.0 and its multimedia extensions, which opened the doors to a common platform for hardware-accelerated graphics (which otherwise required specific code on each game to support the given hardware platform).

 Status: Offline
Profile     Report this post  
NutsAboutAmiga 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 10:10:38
#349 ]
Elite Member
Joined: 9-Jun-2004
Posts: 12273
From: Norway

@cdimauro

Quote:
Well, the o.s. required several changes for AGA. Which, BTW, was an horrible patch over ECS.


Well one most annoying change is HAM8, where the control bit was planes 5 and 6 in HAM6, in HAM8 that was changed to being in lower planes plan 0 and 1.

In HAM6 things where nice color 0 to 16 was solid colors.
while HAM8, color 0, 4, 8, … was solid colors, DPAINT, and programs rearranged colors, so it was not noticed.

In any case, storing the control bits in the image, was also maybe not the best idea, as stole solid colors from the palette.

_________________
http://lifeofliveforit.blogspot.no/
Facebook::LiveForIt Software for AmigaOS

 Status: Offline
Profile     Report this post  
cdimauro 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 11:01:22
#350 ]
Elite Member
Joined: 29-Oct-2012
Posts: 2689
From: Germany

@NutsAboutAmiga

Quote:

NutsAboutAmiga wrote:
@cdimauro

Quote:
Well, the o.s. required several changes for AGA. Which, BTW, was an horrible patch over ECS.


Well one most annoying change is HAM8, where the control bit was planes 5 and 6 in HAM6, in HAM8 that was changed to being in lower planes plan 0 and 1.

In HAM6 things where nice color 0 to 16 was solid colors.
while HAM8, color 0, 4, 8, … was solid colors, DPAINT, and programs rearranged colors, so it was not noticed.

Yup. However the changes with HAM8 made sense, since the upper 6 bits are changing the upper 6 bits of the given color components (keeping the current lower 2 bits).
Quote:
In any case, storing the control bits in the image, was also maybe not the best idea, as stole solid colors from the palette.

What do you mean with that? Could you please clarify it?

 Status: Offline
Profile     Report this post  
NutsAboutAmiga 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 11:34:55
#351 ]
Elite Member
Joined: 9-Jun-2004
Posts: 12273
From: Norway

@cdimauro

I’m not really think about how to implement it, but looks unpractical, as it was implanted.

what if we stored it separately, in own memory block, insted?

Then you won’t need to sacrify the 2bits, you might have had 64 solid colors insted of 16 colors.

You need 4bits for color channel on OCS
(values from 0-15), 2 control bits, 6bits ok on HAM6.

But on HAM8 you have 0-256 values per channel, you need 8bit + 2bit to set color exactly. But the you only get 6bit + 2bit (YYYYYYCC), and in solid color mode, you only have 6bit (64 solid colors).

in OCS and AGA case you have palette tables, that supports 32 (+32 half bright) colors or 256 colors in AGA, only a subset of the color table is used under HAM6/HAM8.

Last edited by NutsAboutAmiga on 07-Aug-2022 at 11:42 AM.
Last edited by NutsAboutAmiga on 07-Aug-2022 at 11:40 AM.
Last edited by NutsAboutAmiga on 07-Aug-2022 at 11:38 AM.

_________________
http://lifeofliveforit.blogspot.no/
Facebook::LiveForIt Software for AmigaOS

 Status: Offline
Profile     Report this post  
cdimauro 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 11:54:55
#352 ]
Elite Member
Joined: 29-Oct-2012
Posts: 2689
From: Germany

@NutsAboutAmiga: OK, got it.

This might be only suitable for HAM8: HAM/HAM6 can already fully change the 4-bit components. Using more than 16 colors for the fixed palette could be very useful, but it'll be a great waste of space (and bandwidth) since you more change color components much more often compared to the fixed colors.

Anyway, HAM8 becomes HAM10 then. With this format you can fully control the 8-bit components, and you also have a base 256 colors palette which helps a lot on reducing the colors transitions.

However the price to pay is 25% space needed and, what's even worse, 10 bitplane points instead of 8, which further complicates the display controller.

It could only make sense with packed graphics, or some hybrid format (e.g.: a packed plane for the 8-bit component and then 2 bitplanes for the control bits or a 2-bit packed plane for them).

 Status: Offline
Profile     Report this post  
NutsAboutAmiga 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 12:29:32
#353 ]
Elite Member
Joined: 9-Jun-2004
Posts: 12273
From: Norway

@cdimauro

Quote:
10 bitplane points


I thinking chunky grouping for control bits.

pixel 0,1,2,3,4,5,6,7

bit: 76543210 76543210
pix: 00112233 44556677

_________________
http://lifeofliveforit.blogspot.no/
Facebook::LiveForIt Software for AmigaOS

 Status: Offline
Profile     Report this post  
cdimauro 
Re: Port AmigaOS 4 to x86
Posted on 7-Aug-2022 13:52:05
#354 ]
Elite Member
Joined: 29-Oct-2012
Posts: 2689
From: Germany

@NutsAboutAmiga

Quote:

NutsAboutAmiga wrote:
@cdimauro

Quote:
10 bitplane points


I thinking chunky grouping for control bits.

pixel 0,1,2,3,4,5,6,7

bit: 76543210 76543210
pix: 00112233 44556677


That looks like my second proposal:
"or the control bits or a 2-bit packed plane for them"

 Status: Offline
Profile     Report this post  
Goto page ( Previous Page 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 )

[ home ][ about us ][ privacy ] [ forums ][ classifieds ] [ links ][ news archive ] [ link to us ][ user account ]
Copyright (C) 2000 - 2019 Amigaworld.net.
Amigaworld.net was originally founded by David Doyle