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Search took 0.07 seconds. Search: Posts Made By: chb
Forum: Retrogaming General Discussion 15 April 2024, 21:56
Replies: 109
Views: 4,899
Posted By chb
Yes, the palette is much more limited compared to...

Yes, the palette is much more limited compared to the A8, but the local color density in standard modes is higher (e.g. Hires 320x200 with two freely selectable colors per 8x8 block). The examples I...
Forum: Retrogaming General Discussion 15 April 2024, 11:11
Replies: 109
Views: 4,899
Posted By chb
I really like the Atari 8-bit, and they obviously...

I really like the Atari 8-bit, and they obviously do have a larger palette, a higher resolution through overscan and a nice display list feature, but also several shortcomings compared to the C64....
Forum: Coders. Asm / Hardware 25 March 2024, 11:19
Replies: 19
Views: 1,134
Posted By chb
It is not possible to have a different x-scroll...

It is not possible to have a different x-scroll value for every bitplane of playfield 2; scroll registers work per playfield. You'd need to either shift two bitplanes with the blitter, have 16 copies...
Forum: Coders. Asm / Hardware 21 February 2024, 15:04
Replies: 338
Views: 387,930
Posted By chb
I know :) But wouldn't a single write (well,...

I know :) But wouldn't a single write (well, rather two to restore it again) to VHPOSW be more efficient than repositioning all 8 Sprites?
Forum: Coders. Asm / Hardware 21 February 2024, 13:56
Replies: 338
Views: 387,930
Posted By chb
But if one does not want/need to restart sprite...

But if one does not want/need to restart sprite DMA, but just show the same sprites again on a different position?
Forum: Coders. General 18 February 2024, 09:31
Replies: 239
Views: 28,660
Posted By chb
It seems like that in Outrun during a stage only...

It seems like that in Outrun during a stage only a smaller subset of objects is shown, and those usually repeat. Hence, does it make sense to cache objects during a stage? So objects would be drawn...
Forum: Coders. Asm / Hardware 15 February 2024, 13:59
Replies: 21
Views: 1,249
Posted By chb
If I did the math correctly, it is indeed a bit...

If I did the math correctly, it is indeed a bit slower than unrolled move.b-s:
32 x move.b (a0)+,(a1)+: 32*12 cycles = 384 cycles
The above code: 404 cycles, of which 192 are for rolling, 148 for...
Forum: Coders. Asm / Hardware 15 February 2024, 13:21
Replies: 21
Views: 1,249
Posted By chb
AFAIR movem.l beats single move.l's when copying...

AFAIR movem.l beats single move.l's when copying >4 longwords, not counting the overhead of the loop or the need to save and restore registers.

BTW, if your source and destination happen to be in...
Forum: Coders. Asm / Hardware 11 February 2024, 14:08
Replies: 21
Views: 1,978
Posted By chb
IMHO an attribute grid could work with a limited...

IMHO an attribute grid could work with a limited palette of up to 8 colors each for foreground background (16 may work, too, but we are after that Speccy look after all :D), using BPLCON4's XOR...
Forum: Retrogaming General Discussion 08 February 2024, 17:56
Replies: 14
Views: 1,093
Posted By chb
The Elektonika BK is super interesting indeed....

The Elektonika BK is super interesting indeed. You are most likely correct that is doesn't have an MMU, as it is a clone of the LSI-11, which also doesn't have one. But there's is LSX for the LSI-11...
Forum: Retrogaming General Discussion 08 February 2024, 10:08
Replies: 14
Views: 1,093
Posted By chb
During the latest month of the German Democratic...

During the latest month of the German Democratic Republic, a clone of the Amstrad CPC called "KC compact (https://en.wikipedia.org/wiki/Amstrad_CPC#KC_compact)" was produced by VEB Mikroelektronik...
Forum: Nostalgia & memories 02 November 2023, 12:52
Replies: 1,335
Views: 157,213
Posted By chb
Yes, you could. Interesting bit of history here: ...

Yes, you could. Interesting bit of history here:
https://www.amigaone.pl/?p=2784 (in Polish)

No, Poland wasn't the Soviet Union. There were western computers sold offically in some eastern bloc...
Forum: Amiga scene 30 October 2023, 14:35
Replies: 1,270
Views: 255,365
Posted By chb
While it is certainly off topic, this is one of...

While it is certainly off topic, this is one of the more interesting information in this thread. Are you sure they were implementations of the 68020 architecture/ISA, and not the 68000? All the...
Forum: Coders. Asm / Hardware 07 September 2023, 14:37
Replies: 6
Views: 1,138
Posted By chb
Those c2p by calms are well known and include...

Those c2p by calms are well known and include routines for a lot of color depths/display modes:
https://github.com/Kalmalyzer/kalms-c2p/tree/main
Forum: Coders. Asm / Hardware 07 September 2023, 12:00
Replies: 6
Views: 1,138
Posted By chb
In general, yes. There are special cases were...

In general, yes. There are special cases were reshuffling the planes is enough, tho, but if you want to remap an arbitrary color index to another arbitrary one, IMHO you have to change the bitmap...
Forum: Coders. Asm / Hardware 19 August 2023, 16:09
Replies: 15
Views: 2,162
Posted By chb
I think that may be correct; movem is 12 cycles...

I think that may be correct; movem is 12 cycles for instruction fetch + n*4 cycles for data transfer (n*8 for longword). EDIT: See last sentence.

Post-increment as destination is AFAIK faster than...
Forum: Coders. Asm / Hardware 12 August 2023, 10:11
Replies: 13
Views: 2,718
Posted By chb
You could also switch to HAM mode at the split,...

You could also switch to HAM mode at the split, that's just one copper instruction... if you only use colors with one component (e.g. blue), you get up to 15 additional non-palette colors. Might not...
Forum: Coders. Asm / Hardware 12 August 2023, 10:01
Replies: 13
Views: 1,268
Posted By chb
Unfortunately it cannot use consecutive cycles,...

Unfortunately it cannot use consecutive cycles, there has to be at least one memory cycle between CPU accesses, both on AGA and OCS/ECS.
Forum: Coders. Asm / Hardware 11 August 2023, 23:23
Replies: 13
Views: 1,268
Posted By chb
That was for raw performance in a copy operation....

That was for raw performance in a copy operation. There's a lot of ways to fill a polygon, both for blitter and CPU. If you e.g. let the blitter draw a polygon span with fill mode, it needs two...
Forum: Coders. Asm / Hardware 11 August 2023, 21:56
Replies: 13
Views: 1,268
Posted By chb
I think w have a misunderstanding. :) Just take...

I think w have a misunderstanding. :) Just take an example: ECS, zero bitplane vs. four bitplane mode, operation is a simple copy. With zero bitplanes, the blitter can use (almost) every memory slot...
Forum: Coders. Asm / Hardware 11 August 2023, 11:34
Replies: 13
Views: 1,268
Posted By chb
It can for some tasks, e.g. clearing memory. In...

It can for some tasks, e.g. clearing memory. In that case, the blitter - like the CPU - can only use every second memory slot, but the CPU-chip mem bus is 32 bit wide (on the A3000), for the blitter...
Forum: Amiga scene 09 August 2023, 17:45
Replies: 1,270
Views: 255,365
Posted By chb
No, T.81 lossless is not used for PhotoCD. It has...

No, T.81 lossless is not used for PhotoCD. It has some superficial similarities to PhotoCD, but the encoding strategy is different. AFAICS, PhotoCD utilizes no intra-picture compression apart from...
Forum: Amiga scene 09 August 2023, 16:41
Replies: 1,270
Views: 255,365
Posted By chb
I think you're confusing PhotoCD with some other...

I think you're confusing PhotoCD with some other standard. PhotoCD is not at all the same as JPEG, and they don't have much in common apart from the fact that they both typically use some sort of YCC...
Forum: Coders. Asm / Hardware 08 August 2023, 18:52
Replies: 41
Views: 3,793
Posted By chb
AFAIR, the 68020 manual mentioned another,...

AFAIR, the 68020 manual mentioned another, non-cache related benefit of alignment: The 68020 always prefetches 32 bit, and does not need an additional bus cycle if the next (word-length) instruction...
Forum: Nostalgia & memories 08 August 2023, 11:04
Replies: 1,335
Views: 157,213
Posted By chb
According to those Commodore documents...

According to those Commodore documents (https://archive.org/details/commodore-post-bankruptcy/page/n41/mode/1up) casework accounted for $3(!) in the A1200's case (no pun intended), the power supply...
Forum: Amiga scene 06 August 2023, 17:11
Replies: 1,270
Views: 255,365
Posted By chb
PhotoCD utilizes a considerably simpler (and less...

PhotoCD utilizes a considerably simpler (and less efficient) compression algorithm than jpeg, AFAIK it is just some kind of YUV with chroma-subsampling, and some Huffman encoding (IMHO only for...
Forum: Amiga scene 06 August 2023, 12:54
Replies: 1,270
Views: 255,365
Posted By chb
Wow, that's less than 0.3 transistors per cache...

Wow, that's less than 0.3 transistors per cache byte! Alien technology from outer space!
Seriously, the cache is external, so it doesn't make much sense to compare the transistor count to the 68060...
Forum: Coders. General 04 August 2023, 12:44
Replies: 23
Views: 2,467
Posted By chb
Constant power paning: center: 45:45...

Constant power paning:

center: 45:45 (64/sqrt(2))
+1 left: 64:0
+1 right: 0:64
Forum: Amiga scene 29 July 2023, 12:43
Replies: 1,270
Views: 255,365
Posted By chb
I think the difference the CDROM made for games...

I think the difference the CDROM made for games that people, at least in Europe/US, mostly bought a console for (action, sport, racing) wasn't that big. The MegaCD (which was earlier than the CD32)...
Forum: Amiga scene 29 July 2023, 11:39
Replies: 1,270
Views: 255,365
Posted By chb
For typical 2D gaming (action gaming), AGA...

For typical 2D gaming (action gaming), AGA couldn't even compete with the SNES which was released in 1990 (much better sprites, more layers, character mode, rotation + zooming, the dog slow CPU isn't...
Forum: Coders. Asm / Hardware 28 July 2023, 11:45
Replies: 46
Views: 4,529
Posted By chb
Hmm, but doesn't the change for color 1 still...

Hmm, but doesn't the change for color 1 still have 4 pixel resolution, as it's done directly with the copper?

EDIT: Sorry, didn't see your 2nd edit :)
Forum: Coders. Asm / Hardware 28 July 2023, 11:26
Replies: 46
Views: 4,529
Posted By chb
@FSizzle: Great idea! And yes, it should be...

@FSizzle: Great idea! And yes, it should be possible to do it without sprite DMA.

@ross: I think the unfill isn't much of a problem, as long as the color change for color 0 appears before the...
Forum: project.Amiga Game Factory 27 July 2023, 11:51
Replies: 126
Views: 21,173
Posted By chb
Rygar is 32 colors front + 8 colors background (+...

Rygar is 32 colors front + 8 colors background (+ copper + sprites) IIRC; the MD can have 64 colors in each of both playfields*, which on the A1200 is only possible using slow masked blitts for the...
Forum: Coders. Asm / Hardware 22 July 2023, 23:44
Replies: 46
Views: 4,529
Posted By chb
Ok, just a back of the envelope calculation for...

Ok, just a back of the envelope calculation for mem access per line, assuming 320 pix width:

Additional bitplane: 20 words/mem cycles
split: 10 words bitplane dma + 2*CWAIT + 2*CMOVE = 18 words...
Forum: Coders. Asm / Hardware 22 July 2023, 11:21
Replies: 46
Views: 4,529
Posted By chb
One could probably also place a sprite at the...

One could probably also place a sprite at the split and blit the bitplane data for that 16 pixel wide stripe into it. That would be enough to hide the two copper color changes.
Forum: Coders. Asm / Hardware 17 July 2023, 21:23
Replies: 26
Views: 2,697
Posted By chb
Very nice trick with the D-fill!

Very nice trick with the D-fill!
Forum: Coders. Asm / Hardware 17 July 2023, 18:46
Replies: 26
Views: 2,697
Posted By chb
What about doing it kind of the other way round?...

What about doing it kind of the other way round? Have a copperlist with a wait for every line, followed by a move to a color register, but then it puts the address of the wait for the next line in...
Forum: Coders. General 16 July 2023, 20:58
Replies: 1,572
Views: 551,843
Posted By chb
OT: The original DOS version of doom included...

OT: The original DOS version of doom included routines for the texture mapping inner loops in asm.
Forum: Amiga scene 08 July 2023, 10:15
Replies: 1,270
Views: 255,365
Posted By chb
The Marty was powered by a 386SX, so one could...

The Marty was powered by a 386SX, so one could argue that it wasn't a real 32 bit system. But ofc those categories were rather pointless anyhow.
Forum: Retrogaming General Discussion 06 May 2023, 14:38
Replies: 22
Views: 2,204
Posted By chb
Darkseed is hi-res interlace afaik, but not...

Darkseed is hi-res interlace afaik, but not completely monochrome - albeit often very close to it and in general rather low saturiation.
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