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Forum: Coders. Asm / Hardware 06 July 2020, 15:02
Replies: 221
Views: 19,768
Posted By chb
Yes, you can have only 128 individual background...

Yes, you can have only 128 individual background pixels, at least if you don't reload the SPRDAT registers (roondar's approach), which is totally flexible, but costs you quite some performance.
...
Forum: Coders. Asm / Hardware 06 July 2020, 13:04
Replies: 221
Views: 19,768
Posted By chb
Just on a side note: Apidya does have parallax...

Just on a side note: Apidya does have parallax scrolling in the last level (the one with the cogwheels in the bg), and it's pretty impressive - a multiplexed 4 color sprite background, which is even...
Forum: Amiga scene 01 July 2020, 11:25
Replies: 45
Views: 2,146
Posted By chb
It's actually slightly more convoluted. The A500...

It's actually slightly more convoluted. The A500 was the original cost-reduced design. The 2000 exists in two versions: the early A2000-A was designed by Commodore Germany. It was heavily based on...
Forum: Coders. General 31 May 2020, 21:28
Replies: 29
Views: 2,700
Posted By chb
For a span filler and solid polygons the blitter...

For a span filler and solid polygons the blitter is in clearing mode (D only)*, so the idle cycles become relevant, meaning the CPU can work at full speed in parallel to the blitter here if no other...
Forum: Coders. General 31 May 2020, 09:30
Replies: 29
Views: 2,700
Posted By chb
If you by "spinning up the Blitter thousand times...

If you by "spinning up the Blitter thousand times per frame" mean a blitter-based span filler, I do not think that's a feasible approach on the Amiga. For pure clear the CPU is as fast as the blitter...
Forum: Coders. General 31 May 2020, 05:43
Replies: 29
Views: 2,700
Posted By chb
You can do a vertical fill by using 2x the target...

You can do a vertical fill by using 2x the target buffer as source, one line apart, and then use an XOR minterm (but no fill mode). Like D = D ^ (D - 1). It then works like a horizontal blitter fill,...
Forum: Coders. General 02 May 2020, 19:41
Replies: 2
Views: 529
Posted By chb
AFAIU the workings of blitter idle cycles were...

AFAIU the workings of blitter idle cycles were largely undocumented, they appear in some early errata to the HRM, but the later eiditons of the HRM seems to omit them completely:...
Forum: Retrogaming General Discussion 26 April 2020, 20:09
Replies: 26
Views: 1,847
Posted By chb
No problem, I guess I should have been better...

No problem, I guess I should have been better aware of the fact that this is the English Amiga Board after all and that there may be certain sensitivities. ;)
Forum: Retrogaming General Discussion 26 April 2020, 19:27
Replies: 26
Views: 1,847
Posted By chb
And you might want to educate yourself a bit...

And you might want to educate yourself a bit about of the use of irony - it might indicated by the utilization of things like smileys. Also that a sentence is followed by another one beginning with...
Forum: support.Hardware 26 April 2020, 09:59
Replies: 23
Views: 1,522
Posted By chb
There's also a manual on the...

There's also a manual on the BigBookOfAmigaHardware-Page for the 1230-IV:
https://www.bigbookofamigahardware.com/bboah/product.aspx?id=1707

Just a warning, it gives a https certificate error,...
Forum: Retrogaming General Discussion 26 April 2020, 08:07
Replies: 26
Views: 1,847
Posted By chb
That's because there's nothing on the Sinclair...

That's because there's nothing on the Sinclair Spectrum that qualifies as music. :D

But seriously, the AY format seems to be the major one for Spectrums (Spectra?) equipped with something else...
Forum: support.Hardware 25 April 2020, 20:47
Replies: 29
Views: 1,899
Posted By chb
Hmm... I guess BW-composite would be sufficient,...

Hmm... I guess BW-composite would be sufficient, as it would simplify the decoder a lot. I cannot imagine they used the color signal, too. But that's just a guess. Some of the Cinergy hybrid sticks...
Forum: support.Hardware 25 April 2020, 19:38
Replies: 29
Views: 1,899
Posted By chb
Very interesting topic! I cannot contribute any...

Very interesting topic! I cannot contribute any experience with teletext on the Amiga, but if you want to investigate further, maybe get an old USB TV dongle? There are ones that support analog TV...
Forum: Retrogaming General Discussion 25 April 2020, 11:41
Replies: 324
Views: 22,908
Posted By chb
Yes, of course, you're absolutely right. But...

Yes, of course, you're absolutely right. But AFAIK all 030/50 accelerators had standard 70 ns or maybe 60 ns FPM RAM, which is not particulary fast when doing random access table lookups. IRC, that...
Forum: Retrogaming General Discussion 25 April 2020, 08:29
Replies: 324
Views: 22,908
Posted By chb
Those 50 are the screen refresh rate. I was just...

Those 50 are the screen refresh rate. I was just showing that bitplane DMA for a 320*256*8 screen takes ~14% of all available chip memory slots, as roondar claimed. And display fetch is 32 bit,...
Forum: Retrogaming General Discussion 25 April 2020, 00:50
Replies: 324
Views: 22,908
Posted By chb
I'm not roondar, but it is actually quite...

I'm not roondar, but it is actually quite straight forward: The Amiga has 3.58e6 chip ram memory cycles (every second clock cycle). Assuming no other DMA and 8 bytes per mem cycle (32 bit/double...
Forum: Retrogaming General Discussion 22 April 2020, 13:37
Replies: 324
Views: 22,908
Posted By chb
When I look at that game, it seems to me that...

When I look at that game, it seems to me that apart from the cut scenes (and maybe replay) one might get away with rotation around only one axis (y) + zoom, maybe even simplifying perspective...
Forum: Retrogaming General Discussion 21 April 2020, 15:20
Replies: 324
Views: 22,908
Posted By chb
Is that really such a big problem? If we take...

Is that really such a big problem? If we take those 200 quads per player, that's around 200 vertexes if one vertex is shared among 4 quads. Probably 16 bit fixed point is sufficient, so we get...
Forum: Amiga scene 10 April 2020, 19:03
Replies: 1,220
Views: 87,978
Posted By chb
It's exactly what the most successful consolo of...

It's exactly what the most successful consolo of that era, the NES, does - the PPU has analog on-chip composite out, as written already earlier. Were Nintendo/Ricoh engineers "plenty crazy"?
And...
Forum: Amiga scene 10 April 2020, 12:43
Replies: 1,220
Views: 87,978
Posted By chb
Yep, and that's him talking about the NTSC...

Yep, and that's him talking about the NTSC composite signal generation. Nothing lunatic about having it on-chip for a game console/home computer that is connected to a TV set - as written earlier, a...
Forum: Amiga scene 07 April 2020, 14:30
Replies: 1,220
Views: 87,978
Posted By chb
AFAIU they were planning to put NTSC composite...

AFAIU they were planning to put NTSC composite signal generation on-chip, which is in fact a very reasonable choice for a game console. The PPU in the NES/Famicom has analog composite out, the VIC-II...
Forum: Amiga scene 05 April 2020, 22:27
Replies: 1,220
Views: 87,978
Posted By chb
That's possible, but I rather think the quoted "7...

That's possible, but I rather think the quoted "7 bitplanes" or sometimes even "128 colors" are a misunderstanding that stems from the fact that ECS has 7 bitplane pointer registers - six for the...
Forum: Amiga scene 05 April 2020, 20:53
Replies: 1,220
Views: 87,978
Posted By chb
Well, following your logic she would mention that...

Well, following your logic she would mention that she has the complete schematics, right? Fact is, we do not know.


Please read my edit. Meaning people from Los Gatos had them and passed them to...
Forum: Amiga scene 05 April 2020, 18:41
Replies: 1,220
Views: 87,978
Posted By chb
While Jeri Ellsworth indeed showed some...

While Jeri Ellsworth indeed showed some schematics in a video, AFAIK it is unknown whether a) those are for the actual chips or something from an earlier stage of development, and b) if she has the...
Forum: Amiga scene 30 March 2020, 20:50
Replies: 1,220
Views: 87,978
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: 1,220
Views: 87,978
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: 1,167
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: 435
Views: 62,235
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: 2,492
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: 2,492
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: 2,492
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: 957
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: 957
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: 19
Views: 2,066
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: 19
Views: 2,066
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: 2,033
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: 3,631
Posted By chb
Mem bandwidth.

Mem bandwidth.
Forum: Retrogaming General Discussion 02 February 2020, 21:43
Replies: 19
Views: 3,631
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: 1,220
Views: 87,978
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: 1,220
Views: 87,978
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...
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