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Forum: Amiga scene Yesterday, 20:50
Replies: 1,085
Views: 72,295
Posted By chb
I think you're overlooking one important point:...

I think you're overlooking one important point: Changing to the newer obsolete fab would have meant a change to CMOS instead of the NMOS/HMOS process used. That means a complete redesign of the chip,...
Forum: Amiga scene 27 March 2020, 10:51
Replies: 1,085
Views: 72,295
Posted By chb
In 1997 a Playstation was $149, a SNES $99. I...

In 1997 a Playstation was $149, a SNES $99. I doubt Commodore could have been able to cover the production costs at those prices, and they weren't in a situation to sell at a big loss and hope to...
Forum: Coders. Asm / Hardware 15 March 2020, 15:12
Replies: 17
Views: 847
Posted By chb
The wikipedia page on color distance has some...

The wikipedia page on color distance has some useful formulas: https://en.wikipedia.org/wiki/Color_difference

If you cannot afford the square root or a table lookup for it, 3*delta_R + 4*delta_G...
Forum: Amiga scene 28 February 2020, 10:40
Replies: 360
Views: 45,585
Posted By chb
First let me say, extremely impressive engine and...

First let me say, extremely impressive engine and very nice demo video! The frame rate looks amazing for the level of detail! And there's even some shaded floor in front of the door - is it somehow...
Forum: Coders. Asm / Hardware 20 February 2020, 16:46
Replies: 46
Views: 2,229
Posted By chb
You're of course fully right concerning the...

You're of course fully right concerning the real-world performance for typical AGA low-res games. And I didn't to want suggest that your code is not optimized or to express criticism about your work,...
Forum: Coders. Asm / Hardware 20 February 2020, 15:22
Replies: 46
Views: 2,229
Posted By chb
But as you wrote in an earlier post - doesn't...

But as you wrote in an earlier post - doesn't this depend on DMA usage? The CPU can do twice as much in one memory access compared to the blitter (32 vs 16 bit), but can get only every second slot....
Forum: Coders. Asm / Hardware 19 February 2020, 17:32
Replies: 46
Views: 2,229
Posted By chb
That might be due to prefetch being aligned to 32...

That might be due to prefetch being aligned to 32 bit addresses:


Also, IIRC the cache entries are aligned to 32 bits, meaning AFAIU that if your code is 256 bytes long, it will not fit into the...
Forum: Coders. Asm / Hardware 17 February 2020, 20:22
Replies: 16
Views: 843
Posted By chb
True, but I was thinking about a double datatype...

True, but I was thinking about a double datatype crossing a quad-longword border, e.g. at an address 0x0c. From my understanding this results in two cache lines being loaded. If I understood it...
Forum: Coders. Asm / Hardware 17 February 2020, 11:50
Replies: 16
Views: 843
Posted By chb
But doesn't the 68040 (and the 030 in burst mode)...

But doesn't the 68040 (and the 030 in burst mode) always fetch a complete cache line (16 bytes)? So I 'd assume having 64-bit or 96-bit data types aligned to the respective boundaries (double...
Forum: Coders. General 15 February 2020, 17:47
Replies: 17
Views: 1,384
Posted By chb
If you want to use an existing program, then...

If you want to use an existing program, then there's also hamconvert
(http://mrsebe.bplaced.net/blog/wordpress/?page_id=374) which, despite the name, supports EHB and has a batch mode.

PS:...
Forum: Coders. General 15 February 2020, 13:50
Replies: 17
Views: 1,384
Posted By chb
I used (for another color reduction problem, not...

I used (for another color reduction problem, not EHB) a modified k-means algorithm, where I substituted the euclidean distance by a custom distance function. I guess in the case of EHB, the centers...
Forum: Retrogaming General Discussion 11 February 2020, 19:36
Replies: 29
Views: 1,782
Posted By chb
Yep, all the parallax background is essentially...

Yep, all the parallax background is essentially just one char that gets scrolled (it does not need to be precomputed, even the C64 is fast enough to scroll an 8x8 char with the CPU each frame ;)).
...
Forum: Retrogaming General Discussion 02 February 2020, 22:23
Replies: 19
Views: 3,502
Posted By chb
Mem bandwidth.

Mem bandwidth.
Forum: Retrogaming General Discussion 02 February 2020, 21:43
Replies: 19
Views: 3,502
Posted By chb
Kid Chaos is 5 bitplanes, dual playfield; meaning...

Kid Chaos is 5 bitplanes, dual playfield; meaning 7 colors foreground and 4 colors background. They might have fixed color 0 for the border, so 3 remaining colors that could be freely changed/used...
Forum: Amiga scene 02 February 2020, 17:19
Replies: 1,085
Views: 72,295
Posted By chb
That's certainly a valid aspect; also all other...

That's certainly a valid aspect; also all other integrated-keyboard computers of that time that I'm aware of with internal HDD had 2.5" internal drives (Atari Falcon 030, A600/A1200, Acorn A3020), so...
Forum: Amiga scene 01 February 2020, 18:53
Replies: 1,085
Views: 72,295
Posted By chb
That definitely never ever happened. ;) Joking...

That definitely never ever happened. ;)
Joking aside, 2.5" drives were more shockproof, because they were made for laptops and had smaller discs; but unless you were dropping your Amiga regularly...
Forum: Amiga scene 01 February 2020, 14:10
Replies: 1,085
Views: 72,295
Posted By chb
I think it was a terrible idea. I had a 3.5"...

I think it was a terrible idea. I had a 3.5" drive running outside my A1200 in a wooden box, having to cut the case slightly to get the IDE cable out, while the power came from an Y-adapter to the...
Forum: Retrogaming General Discussion 01 February 2020, 13:19
Replies: 42
Views: 2,778
Posted By chb
I guess almost all first person shooters on AGA...

I guess almost all first person shooters on AGA used 256 color mode; those using copper chunky like AB3D probably* used it too, but the resulting screen mode is 4096 colors.


* it's possible to...
Forum: Retrogaming General Discussion 01 February 2020, 11:31
Replies: 42
Views: 2,778
Posted By chb
Virtual Karting (1 and 2) is using super hires to...

Virtual Karting (1 and 2) is using super hires to simulate some sort of low-res chunky mode best suited for TV sets/composite video.
Forum: support.Apps 31 January 2020, 23:11
Replies: 39
Views: 1,825
Posted By chb
I think there are three main reasons the Atari ST...

I think there are three main reasons the Atari ST had the edge over the Amiga when it came to word processing:

1) The monochrome mode and the SM124 monitor - 640x400 in 70 Hz non-interlace is much...
Forum: project.Amiga Game Factory 28 January 2020, 14:04
Replies: 117
Views: 6,666
Posted By chb
;) Oh, that's very cool, thanks for the...

;)


Oh, that's very cool, thanks for the info! I guess this means priorities behave exactly like in dual playfield with regard to the bitplanes, but colors like in single playfield mode? That...
Forum: project.Amiga Game Factory 28 January 2020, 11:08
Replies: 117
Views: 6,666
Posted By chb
The problem here, if I'm not mistaken, are the...

The problem here, if I'm not mistaken, are the priorities in single playfield mode. Sprites can only go in front of or behind everything that is bitmap (well, apart from color 0 of course), so you...
Forum: Retrogaming General Discussion 27 January 2020, 18:43
Replies: 83
Views: 4,166
Posted By chb
They produced a DCTV card for the CDTV (never...

They produced a DCTV card for the CDTV (never sold officially, AFAIK) - the CDTV has a video slot, so I guess something like that was planed from quite early on (It would possibly have been called...
Forum: Retrogaming General Discussion 26 January 2020, 16:40
Replies: 83
Views: 4,166
Posted By chb
Yes! :D No. It is not an advantage in that...

Yes! :D

No. It is not an advantage in that case, because for vector quantization codecs you need to split your image in some kind of tiles anyway.


One (uncompressed) 320x200 16 color IFF-ILBM...
Forum: Retrogaming General Discussion 26 January 2020, 16:10
Replies: 83
Views: 4,166
Posted By chb
FMV games on the Mega CD usually used some...

FMV games on the Mega CD usually used some version of the Cinepak codec specially adapted for the hardware. That codec is based on vector quantization, which broadly speaking means you construct your...
Forum: support.Apps 24 January 2020, 09:49
Replies: 39
Views: 1,825
Posted By chb
At least 60 Hz would have been possible; some...

At least 60 Hz would have been possible; some flickerfixers seem to support the Euro36 mode (ECS 15 kHZ, maybe even with ECS Agnus only), which then gives you 640x400 @70 Hz (de-)interlaced, with...
Forum: Nostalgia & memories 16 January 2020, 15:42
Replies: 153
Views: 6,263
Posted By chb
There are some, like Bloodshot, Duke Nukem 3D,...

There are some, like Bloodshot, Duke Nukem 3D, Zero Tolerance or the 3D Levels from Toy Story... albeit they technically are rather less advanced than those you mentioned. But Bloodshot e.g. is 1x1...
Forum: Nostalgia & memories 13 January 2020, 14:37
Replies: 53
Views: 3,052
Posted By chb
In addition to what roondar wrote above, sprites...

In addition to what roondar wrote above, sprites on the consoles usually have more flexible palettes - on the OCS Amigas, the sprite colors are always from the 17-31 range, and have fixed palette...
Forum: Coders. Asm / Hardware 10 January 2020, 16:06
Replies: 11
Views: 578
Posted By chb
I was wondering - can you overcome the sprite...

I was wondering - can you overcome the sprite limit at higher fetch modes by fiddling with HSSTRT/HSSTOP and HBSTRT/HBSTOP? Usually you'd need to shift your picture 64 pix to the right to keep the...
Forum: Coders. General 16 December 2019, 17:33
Replies: 17
Views: 997
Posted By chb
I thought of blitter shift; AFAIU changing your...

I thought of blitter shift; AFAIU changing your source was not an option (apart from adding ones. If you can draw it shifted, there's no need to use the second buffer.

Filling is just an...
Forum: Coders. General 16 December 2019, 16:58
Replies: 17
Views: 997
Posted By chb
WARNING, NOT TESTED :D Maybe you could...

WARNING, NOT TESTED :D
Maybe you could left-shift your source by one pixel, then use exclusive fill with FCI set to 1:

00100
00010
00001
00000
00000

Shift:
Forum: Nostalgia & memories 09 December 2019, 21:05
Replies: 24
Views: 2,167
Posted By chb
If you'd side with Mark Gallagher, Crime Inc...

If you'd side with Mark Gallagher, Crime Inc (http://hol.abime.net/6113) probably scores quite high on that list... :)
Forum: support.Apps 26 November 2019, 15:04
Replies: 13
Views: 1,124
Posted By chb
AFAIK there was no Macintosh with less than 128k...

AFAIK there was no Macintosh with less than 128k of RAM. However, the ROM on the first models was only 64k in size, so combined the space for OS + programs was really tiny compared to even the base...
Forum: Amiga scene 08 November 2019, 10:53
Replies: 360
Views: 45,585
Posted By chb
What you described is true for D-only blits (see...

What you described is true for D-only blits (see the HRM (http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node0127.html) for details). AB->D can use every available memory cycle,...
Forum: Amiga scene 07 November 2019, 23:32
Replies: 360
Views: 45,585
Posted By chb
Idle cycles are cycles the blitter cannot use and...

Idle cycles are cycles the blitter cannot use and are left to the cpu, if requested by it and not used by any other higher priority dma. It gets more complicated because a blitter idle cycle can only...
Forum: Coders. General 07 November 2019, 21:50
Replies: 2,263
Views: 352,937
Posted By chb
AFAIK most A500 from MoBo Rev. 6A on and later...

AFAIK most A500 from MoBo Rev. 6A on and later (probably since around 1989 or so) had some kind of ECS Agnus*. I think memory expansion was by default configured as slow mem, but it was possible to...
Forum: Coders. General 07 November 2019, 20:50
Replies: 2,263
Views: 352,937
Posted By chb
+1 ECS somehow's neither fish nor flesh. ...

+1 ECS somehow's neither fish nor flesh.



AFAIK only the ECS Agnus models can address 1 MB chip mem, so 8372A and above; the original Fat Agnus (8370 and 8371) in the early A500 and A2000...
Forum: Amiga scene 07 November 2019, 11:44
Replies: 360
Views: 45,585
Posted By chb
It actually could be quite useful to maximize...

It actually could be quite useful to maximize memory bandwidth usage. Consider you have a blit running and finishing during bitplane dma - it will steal cycles from the CPU that the CPU could have...
Forum: Coders. Asm / Hardware 06 November 2019, 14:10
Replies: 18
Views: 956
Posted By chb
Have you considered using log tables for...

Have you considered using log tables for multiplication? Like x*y = b^(log_b x + log_b y)? Needs a log table entry for every possible value x or invsqr can take, and an inverse one for every one the...
Forum: Amiga scene 04 November 2019, 22:47
Replies: 99
Views: 6,754
Posted By chb
set;print """ MakeDir RAM:ENV Assign >NIL:...

set;print """
MakeDir RAM:ENV
Assign >NIL: ENV: RAM:ENV
LoadWB
EndCLI >NIL;"""


:D:D:D
(should work with WB 2.1 and above)
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