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Forum: Coders. Asm / Hardware 04 May 2019, 03:15
Replies: 14
Views: 632
Posted By mc6809e
If you time it correctly, you should be able to...

If you time it correctly, you should be able to start blitting a little before display fetch ends. Just make sure display fetch wins the race for access to the playfield.

And if you use...
Forum: Coders. Asm / Hardware 11 April 2019, 04:10
Replies: 20
Views: 2,718
Posted By mc6809e
For copying you can't beat the blitter with the...

For copying you can't beat the blitter with the 68000.

It's another story with clearing. That's much more complicated.

Clearing by the blitter uses one idle cycle and one write cycle. Because...
Forum: Coders. Asm / Hardware 08 April 2019, 03:50
Replies: 30
Views: 3,799
Posted By mc6809e
Good question. Some of the better informed around...

Good question. Some of the better informed around here might be able to tell you. I think there are a few tricks typically done for efficiency that might fail.



Either line 0 or line 1,...
Forum: Coders. Asm / Hardware 08 April 2019, 03:12
Replies: 30
Views: 3,799
Posted By mc6809e
Very nice! Looks awesome!

Very nice! Looks awesome!
Forum: Coders. Asm / Hardware 07 April 2019, 04:19
Replies: 30
Views: 3,799
Posted By mc6809e
You seem really committed! Want a challenge? How...

You seem really committed! Want a challenge? How about trying to make a copper-driven blitter queue that even crosses frame boundaries? In other words, it works even when VBLANK resets the copper...
Forum: Nostalgia & memories 14 February 2019, 04:56
Replies: 76
Views: 7,537
Posted By mc6809e
Uhg. So you think the sinc function is simple?...

Uhg. So you think the sinc function is simple? It's not even finite!

But of course we don't really need the entire sinc function. But we still need enough of it to convolve it with the sample. And...
Forum: Coders. General 30 January 2019, 03:57
Replies: 15
Views: 4,243
Posted By mc6809e
I'd love to see a 3d game that uses the blitter...

I'd love to see a 3d game that uses the blitter to the max. I mean of course a completely generic blitter queue controlled by the copper. It is possible -- even while blits are running across frames.
Forum: Nostalgia & memories 30 January 2019, 03:52
Replies: 76
Views: 7,537
Posted By mc6809e
A problem with digital audio, IMHO, is with the...

A problem with digital audio, IMHO, is with the belief that because we have all the samples necessary for perfect reconstruction we get perfect reconstruction when those samples are output through...
Forum: support.Hardware 26 January 2019, 04:03
Replies: 8
Views: 597
Posted By mc6809e
I put a 68010 in an A500. Very little speed up...

I put a 68010 in an A500. Very little speed up and too many problems for it to be worth the bother.
Forum: Retrogaming General Discussion 08 January 2019, 05:16
Replies: 147
Views: 9,847
Posted By mc6809e
This misunderstanding has been going on for ages....

This misunderstanding has been going on for ages.

The problem is with the loose definition of "sample". Paula may be OR MAY NOT BE outputting a sample when it generates sounds.

What Paula does...
Forum: Retrogaming General Discussion 22 December 2018, 04:06
Replies: 52
Views: 3,730
Posted By mc6809e
If you're using blitz basic for blits then, yeah,...

If you're using blitz basic for blits then, yeah, the blitter is going to appear slow.

And if you're blitting and waiting and then blitting and waiting and on and on, it's going to appear to be...
Forum: Coders. Asm / Hardware 08 December 2018, 04:56
Replies: 1,000
Views: 43,900
Posted By mc6809e
Two things. First, if you're going to count the...

Two things. First, if you're going to count the loading of addresses, you have to count the loading of the segment registers. That's going to cost instructions.

But that's silly anyway. The...
Forum: Coders. AMOS 04 December 2018, 04:44
Replies: 6
Views: 1,989
Posted By mc6809e
Sprites are probably best if treated like their...

Sprites are probably best if treated like their own, narrow, relatively static, playfield as an overlay, like for scores, lives left, power, etc.
Forum: Coders. Asm / Hardware 25 November 2018, 04:59
Replies: 1,000
Views: 43,900
Posted By mc6809e
It occurs to me that a slight modification to the...

It occurs to me that a slight modification to the emulator's cpu code that removes the idle cycles during branch instructions might give a visual idea of the extent to which the 68K falls short using...
Forum: Coders. Asm / Hardware 18 November 2018, 18:27
Replies: 1,000
Views: 43,900
Posted By mc6809e
Lots of data from Intel concerning the 8086 vs...

Lots of data from Intel concerning the 8086 vs 68000 vs 80286:

http://www.bitsavers.org/components/intel/80186/210826_iAPX_186_286_Benchmark_Report_Oct82.pdf

Several of their own benchmarks...
Forum: Coders. Asm / Hardware 17 November 2018, 20:52
Replies: 1,000
Views: 43,900
Posted By mc6809e
Yeah, the three refresh DMA cycles at the...

Yeah, the three refresh DMA cycles at the beginning of each scanline is going to cause at least one instruction to take 8 cycles instead of 6.

Still, it's nice seeing confirmation that most of...
Forum: Coders. Asm / Hardware 17 November 2018, 04:25
Replies: 1,000
Views: 43,900
Posted By mc6809e
What about for zero planes, like during the...

What about for zero planes, like during the overscan and HBlank and VBlank?

Dang it. Now I'm getting sucked into another ST vs Amiga blackhole.

Ignoring that, I think the bus access timing...
Forum: Coders. Asm / Hardware 16 November 2018, 03:46
Replies: 1,000
Views: 43,900
Posted By mc6809e
Except that a memory cycle can start on a 2 cycle...

Except that a memory cycle can start on a 2 cycle boundary. It still takes 4 cycles to complete the access but an instruction can actually take a multiple of 2 cycles.

It's one thing that makes...
Forum: Coders. Asm / Hardware 15 November 2018, 04:48
Replies: 1,000
Views: 43,900
Posted By mc6809e
Yeah, you're right, of course. Terje has...

Yeah, you're right, of course.

Terje has said that you could very well estimate the speed of most code by simply counting the total number of memory accesses needed.

Anyone really interested...
Forum: Coders. Asm / Hardware 15 November 2018, 04:44
Replies: 1,000
Views: 43,900
Posted By mc6809e
This might already be somewhere around here but I...

This might already be somewhere around here but I thought I'd post it as it seems somewhat relevant:

http://nemesis.hacking-cult.org/MegaDrive/Documentation/Yacht.txt

Amazing document...
Forum: Coders. Asm / Hardware 12 November 2018, 03:56
Replies: 1,000
Views: 43,900
Posted By mc6809e
I'm surprised no one mentioned a potentially...

I'm surprised no one mentioned a potentially difficult problem using x86 segments and C: pointer aliasing issues.

It's entirely possible for two pointers to point to precisely the same memory...
Forum: Coders. Asm / Hardware 04 November 2018, 03:17
Replies: 1,000
Views: 43,900
Posted By mc6809e
Instruction prefetch on the 68k is hard coded....

Instruction prefetch on the 68k is hard coded. Each instruction, besides performing its primary operation, will prefetch the first word of the next instruction in the same way every time. This means...
Forum: Hardware mods 29 September 2018, 04:14
Replies: 518
Views: 118,550
Posted By mc6809e
Back in the day I used the piggy-back method to...

Back in the day I used the piggy-back method to bring my A500 to 1Meg.

I can't remember the details but basically I soldered another 16 chips on top of the 16 already on the motherboard, making...
Forum: support.Apps 18 April 2015, 03:58
Replies: 17
Views: 3,316
Posted By mc6809e
I wonder what these videos would look like if the...

I wonder what these videos would look like if the Amiga designers had stuck with using an YIQ or YUV scheme instead of RGB. Probably much better (assuming proper coding).

Maybe they should have...
Forum: support.Hardware 10 March 2015, 13:15
Replies: 42
Views: 4,132
Posted By mc6809e
The first is just a student's report drawn from...

The first is just a student's report drawn from other sources. Nothing there really.

The second is a test of multipath, but at the smallest tested interval of 2 microseconds, the interfering path...
Forum: support.Hardware 09 March 2015, 21:42
Replies: 42
Views: 4,132
Posted By mc6809e
The idea that the OFDM of DVB-T is multipath...

The idea that the OFDM of DVB-T is multipath resistant is mostly a myth.

It should be obvious that mixing the OFDM signal with a carrier re-narrows the signal and the multipath advantage almost...
Forum: support.Hardware 07 March 2015, 04:36
Replies: 42
Views: 4,132
Posted By mc6809e
Nearly the same signal. The only thing PAL...

Nearly the same signal.

The only thing PAL did was invert the chroma phase of every other line so that any shift in one line could be compensated for by the next line.

It did result in reducing...
Forum: support.Hardware 06 March 2015, 20:39
Replies: 42
Views: 4,132
Posted By mc6809e
PAL flicker is miserable. I don't know how anyone...

PAL flicker is miserable. I don't know how anyone can stand it.
Forum: Amiga scene 02 March 2015, 22:59
Replies: 34
Views: 10,965
Posted By mc6809e
Excellent, Bean! Thanks!

Excellent, Bean! Thanks!
Forum: Amiga scene 02 March 2015, 06:57
Replies: 34
Views: 10,965
Posted By mc6809e
Sorry ;) Oh, I just meant that since...

Sorry ;)



Oh, I just meant that since the CPU is usually busy with other calculations of all sorts while the blitter is less taxed, adding a cross product calculation for a surface normal plus...
Forum: Amiga scene 01 March 2015, 22:04
Replies: 34
Views: 10,965
Posted By mc6809e
Thanks for your thoughts, Beany. Appreciated. But...

Thanks for your thoughts, Beany. Appreciated. But by my math, your cube example actually argues for doing three single-bitplane fills.

Doing three separate one-bitplane fills I get:

14 words x...
Forum: Amiga scene 26 February 2015, 07:08
Replies: 34
Views: 10,965
Posted By mc6809e
Ah, that final statement suggests to me that I...

Ah, that final statement suggests to me that I maybe I haven't been clear enough.

What I'm talking about is first drawing one filled single bitplane polygon of a larger object in a buffer. Then by...
Forum: Amiga scene 25 February 2015, 20:36
Replies: 34
Views: 10,965
Posted By mc6809e
That seems like it would often take more time....

That seems like it would often take more time. There's the larger off screen buffer to clear. And twice as much memory to cover with the fill. I can see how it might be competitive for small polys,...
Forum: Amiga scene 25 February 2015, 04:46
Replies: 34
Views: 10,965
Posted By mc6809e
But you can't usually render a poly directly to a...

But you can't usually render a poly directly to a frame buffer unless it's the only poly to be rendered, unless I'm missing something.

The best way, IMO, is to first render/fill the poly to a...
Forum: support.Games 22 February 2015, 04:48
Replies: 19
Views: 5,175
Posted By mc6809e
Oh it's easy to write a chess playing program...

Oh it's easy to write a chess playing program that takes just a few seconds to make a decision.

Those decisions won't be good ones, but they can be made quickly.
Forum: support.Games 20 February 2015, 09:00
Replies: 19
Views: 5,175
Posted By mc6809e
The CPU of the Amiga would probably limit...

The CPU of the Amiga would probably limit stockfish's rating.

If Chessmaster 2100 was written in assembler, it might actually be a better player on the Amiga than stockfish's compiled c++ running...
Forum: Nostalgia & memories 18 February 2015, 22:49
Replies: 131
Views: 14,785
Posted By mc6809e
The C128 stunk because it confused consumers'...

The C128 stunk because it confused consumers' perception of Commodore's commitment to the Amiga.

How's that?
Forum: Retrogaming General Discussion 07 February 2015, 07:19
Replies: 57
Views: 7,778
Posted By mc6809e
You're not too dumb. The problem is that...

You're not too dumb.

The problem is that you're aware of more important things and those things distract you.
Forum: Nostalgia & memories 04 February 2015, 20:39
Replies: 2,424
Views: 361,765
Posted By mc6809e
I think the designers believed that more complex...

I think the designers believed that more complex stereo effects would be done by simply duplicating most channel settings and altering the volume on pairs of channels to place the audio in space.
...
Forum: support.Hardware 25 January 2015, 16:48
Replies: 11
Views: 1,505
Posted By mc6809e
The problem could be a marginal IC or other...

The problem could be a marginal IC or other component that fails as it heats up, often due to a high resistance internal short.

Carefully touch the top of each IC to see if its VERY hot. Don't...
Showing results 1 to 40 of 304

 
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