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Forum: Coders. Asm / Hardware 14 November 2018, 21:16
Replies: 852
Views: 29,035
Posted By coder76
It's not easy to compare instruction cycle count...

It's not easy to compare instruction cycle count between various architectures. If you look in MC68020 manual, there's 3 cases given for each instruction, best, cache and worst. Typically you would...
Forum: Retrogaming General Discussion 27 October 2018, 21:01
Replies: 155
Views: 7,681
Posted By coder76
I think AGA is still underrated in terms of...

I think AGA is still underrated in terms of performance vs. OCS. While AGA was not designed to run games like Doom and Quake, it turned out that these will run decently on an AGA machine with enough...
Forum: Retrogaming General Discussion 29 September 2018, 18:34
Replies: 155
Views: 7,681
Posted By coder76
Wolfenstein does run on high-end 286's, and also...

Wolfenstein does run on high-end 286's, and also on a 386SX. Doom requires better hardware, so a 386/40 MHz is probably a minimum, and it won' run fast on that. Doom runs on Amiga too, but requires a...
Forum: Coders. Asm / Hardware 25 September 2018, 17:54
Replies: 70
Views: 2,350
Posted By coder76
Yes, but we were talking about handling GCR...

Yes, but we were talking about handling GCR format with Amiga's native disk drives. This A1020 is some external disk drive which has its own drive mechanism, and probably is connected to Amiga via...
Forum: Coders. Asm / Hardware 25 September 2018, 10:26
Replies: 70
Views: 2,350
Posted By coder76
In Wikipedia there is an article about GCR format...

In Wikipedia there is an article about GCR format and some of its variations. Apple used three different encodings, of which the two first were pretty poor in terms of encoding efficiency. Then later...
Forum: Coders. Asm / Hardware 21 September 2018, 23:46
Replies: 70
Views: 2,350
Posted By coder76
I remember that I tried to implement GCR format...

I remember that I tried to implement GCR format reading and writing to floppy disk as described in Amiga Disk Drives Inside & Out, but it didn't work at all. Not sure where problem is, but got only...
Forum: News 19 September 2018, 15:16
Replies: 341
Views: 52,634
Posted By coder76
Has there been a fix to these guru meditation...

Has there been a fix to these guru meditation boxes and early bootup screen that you activate with both mouse buttons, that they also work with ~30 kHz displays? Now it looks to me under AmigaOS 3.1...
Forum: Amiga scene 29 August 2018, 12:11
Replies: 67
Views: 3,630
Posted By coder76
Old PC desktop models ranging from 286 to Pentium...

Old PC desktop models ranging from 286 to Pentium MMX and Pentium Pro aren't cheap either, they usually cost several hundred USD. Prices start to go down with Pentium II, which you can get for less...
Forum: Coders. Asm / Hardware 21 August 2018, 19:37
Replies: 852
Views: 29,035
Posted By coder76
Here's a list of x86 instruction clock cycles...

Here's a list of x86 instruction clock cycles from 8088-Pentium:
https://www.cs.dartmouth.edu/~mckeeman/cs48/mxcom/doc/x86.html

Compared to a 286, a 68000 seems slow. It's 5 clock cycles for a...
Forum: Coders. General 13 August 2018, 22:13
Replies: 62
Views: 13,778
Posted By coder76
Not necessarily. Stardust used this mirroring...

Not necessarily. Stardust used this mirroring technique in the tunnel sequences with dualplayfield, so the objects were in a different playfield. But then you're limited to 3+3 bitplanes, which may...
Forum: Coders. General 09 August 2018, 23:22
Replies: 120
Views: 8,173
Posted By coder76
It isnt clear from your writings how you fill...

It isnt clear from your writings how you fill your polygons, but you should fill only 1 bitplane per surface, so if you have a 4 bitplane screen, then you have only 4 colors available (0001, 0010,...
Forum: Nostalgia & memories 04 August 2018, 01:21
Replies: 106
Views: 12,892
Posted By coder76
Yes, but all is not lost here, after writing into...

Yes, but all is not lost here, after writing into chip ram, the 68030 can continue executing code in parallell in fast ram, provided no more memory accesses are done during these 28 cycles. This...
Forum: New to Emulation or Amiga scene 09 July 2018, 16:55
Replies: 45
Views: 3,376
Posted By coder76
Yes, you are right, I was thinking too much in...

Yes, you are right, I was thinking too much in terms of how amiga memory system works. The PC's have always had better bandwidth for their CPUs to their video memory than Amigas.
Forum: New to Emulation or Amiga scene 09 July 2018, 14:05
Replies: 45
Views: 3,376
Posted By coder76
It's not possible to run 640x480 with 256 colors...

It's not possible to run 640x480 with 256 colors and 60 Hz on a standard ISA bus. There were some special screenmodes available that could run with lower refresh rates and lower resolution with 256...
Forum: New to Emulation or Amiga scene 09 July 2018, 13:48
Replies: 45
Views: 3,376
Posted By coder76
The VGA standard was made for the ISA bus, which...

The VGA standard was made for the ISA bus, which was a standard back then on the PC's. However, the ISA bus has a too limited bandwidth to support more than 16 colors in 640x480. This is where AGA is...
Forum: Coders. General 07 July 2018, 19:45
Replies: 587
Views: 48,383
Posted By coder76
I think your calculations are not entirely...

I think your calculations are not entirely correct. 128 bytes for gfx and 32 for mask are clear, but you're saying total overhead is 928 bytes? It's too much. A 32 bit CPU wouldn't also write 16...
Forum: Coders. General 06 July 2018, 22:18
Replies: 587
Views: 48,383
Posted By coder76
This can't be true, initially I would have...

This can't be true, initially I would have estimated max number of sprites to be around 500. Then I found this documentation, which says that X68000 has 128 sprites, but the author found a way to...
Forum: Coders. General 06 July 2018, 18:35
Replies: 587
Views: 48,383
Posted By coder76
Well it seemed to me that AnimaInCorpore doubted...

Well it seemed to me that AnimaInCorpore doubted that it would be possible to make some more high-end bullet hell shooter on an A1200 like Cho Ren Sha. Yes, not possible on an unexpanded A1200, one...
Forum: Coders. General 06 July 2018, 17:22
Replies: 587
Views: 48,383
Posted By coder76
If one wants to have something more high-end,...

If one wants to have something more high-end, then one should use an accelerator board with an A1200, and draw most object graphics with the CPU, because the blitter is way too slow. I did some tests...
Forum: Coders. Asm / Hardware 11 March 2018, 17:59
Replies: 54
Views: 9,769
Posted By coder76
Could you be more specific? The tests on my...

Could you be more specific? The tests on my Blizzard IV board on an A1200 with a 68030/50 MHz and fast ram gives over 10 MB/sec with cpu + blitter performing straight copies into chip ram at same...
Forum: Coders. Asm / Hardware 11 March 2018, 13:19
Replies: 54
Views: 9,769
Posted By coder76
Yes ok, but I still think GameSmith doesn't offer...

Yes ok, but I still think GameSmith doesn't offer what I'm looking for. After reading some Atari Forums, I became interested in how one could implement software sprites on Amiga, and that means...
Forum: Coders. Asm / Hardware 10 March 2018, 23:10
Replies: 54
Views: 9,769
Posted By coder76
@Samurai Crow Thanks for the idea, but I'm used...

@Samurai Crow
Thanks for the idea, but I'm used to hack Amiga hardware directly with just asm and maybe C. Got some experience from past, so not starting from a clean table.

@PeterK
Yes, ok. It...
Forum: Coders. Asm / Hardware 10 March 2018, 20:07
Replies: 54
Views: 9,769
Posted By coder76
I don't know how FBlit works in detail, but of...

I don't know how FBlit works in detail, but of course you need to store your data in both fast and chip ram, if blitter and CPU operates on same objects. Mainly thought about fonts, icons and some...
Forum: Coders. Asm / Hardware 10 March 2018, 18:32
Replies: 54
Views: 9,769
Posted By coder76
Can Fblit use CPU and blitter at same time for...

Can Fblit use CPU and blitter at same time for same tasks? on AGA machines with fastram, there is certainly enough bandwidth for CPU and blitter to work in parallell into chip ram. With 32-bit memory...
Forum: Retrogaming General Discussion 09 March 2018, 13:15
Replies: 67
Views: 3,338
Posted By coder76
Yes, you need both a blitter and horizontal...

Yes, you need both a blitter and horizontal HW-scroll to compete with Amiga games. But even then Atari STe doesn't have some features that Amiga has, like hardware sprites, dual playfield, and more...
Forum: Retrogaming General Discussion 09 March 2018, 01:02
Replies: 67
Views: 3,338
Posted By coder76
Atari failed pretty badly with their hardware. At...

Atari failed pretty badly with their hardware. At first, they didn't want to use a blitter, because it was too expensive, and then when it became cheaper, they started installing it in later Atari...
Forum: Amiga scene 02 March 2018, 22:21
Replies: 63
Views: 2,305
Posted By coder76
It's called Sega Megafire, it has some added...

It's called Sega Megafire, it has some added functionality, like autofire for each button. So not the standard pad I believe. I think also that various Sega pads require different code to work, which...
Forum: Amiga scene 02 March 2018, 21:59
Replies: 63
Views: 2,305
Posted By coder76
I tested an old 3 button Megadrive controller...

I tested an old 3 button Megadrive controller (buttons A, B, C) with a few games on an A1200, and only Turrican 2 worked. ADoom for example didn't respond to button "C", but then when "B" (fire...
Forum: Coders. General 02 March 2018, 13:34
Replies: 15
Views: 1,158
Posted By coder76
Well, it's the usual horizontal HW-scrolling with...

Well, it's the usual horizontal HW-scrolling with the lava field. With copper, you can make several regions vertically which each have their own colors, scrollspeed, and bitmaps to scroll in.
Forum: Amiga scene 01 March 2018, 10:33
Replies: 63
Views: 2,305
Posted By coder76
But one should be a bit careful though, these new...

But one should be a bit careful though, these new cheap editions of e.g. Genesis controllers can also be very poor in quality. Not corresponding to original quality, and size is different. Look at...
Forum: Amiga scene 28 February 2018, 22:27
Replies: 63
Views: 2,305
Posted By coder76
The Sega Megadrive/Genesis controllers work also...

The Sega Megadrive/Genesis controllers work also on Amiga and are pretty cheap. You get 2 buttons on both to work, but soldering is required to get third button to work. Haven't tested myself, but...
Forum: Coders. Asm / Hardware 21 February 2018, 17:00
Replies: 164
Views: 15,676
Posted By coder76
Yes, but I think leaving DMA support out here was...

Yes, but I think leaving DMA support out here was a good idea, as decoding an MFM track doesn't take a long time anyway, probably less than 1/50 s judging on data amount. This gives flexibility to...
Forum: Coders. Asm / Hardware 21 February 2018, 15:34
Replies: 164
Views: 15,676
Posted By coder76
I don't think that the Amiga floppy hardware is...

I don't think that the Amiga floppy hardware is poorly designed. It is more flexible than the PC floppy controller, Amiga can read 720 kb DOS disks, but the PC disk drive can't read Amiga formatted...
Forum: Amiga scene 20 February 2018, 18:04
Replies: 336
Views: 30,123
Posted By coder76
I also agree that Bomb Jack looks good as it is....

I also agree that Bomb Jack looks good as it is. And instead of trying to tweak with the OCS hardware, why not do an AGA version instead? With AGA you can have a better resolution and lots of colors...
Forum: Amiga scene 15 February 2018, 13:38
Replies: 63
Views: 2,838
Posted By coder76
Does an unexpanded A1200 really cost 300-400 €...

Does an unexpanded A1200 really cost 300-400 € these days? Or is it with an additional memory /accelerator expansion?
Forum: Retrogaming General Discussion 07 January 2018, 14:58
Replies: 36
Views: 2,050
Posted By coder76
I had an opportunity to test this SNES mini, but...

I had an opportunity to test this SNES mini, but didnt like it. The games look very blocky on a modern LCD display, almost like C64 games. This is because SNES has a 256x240 resolution in most games....
Forum: Coders. AMOS 17 December 2017, 07:55
Replies: 3
Views: 1,131
Posted By coder76
The copper does not usually have time to change...

The copper does not usually have time to change all colors and other values etc. that is required for a new screen, if there is not a whole scanline available. During that time the palette is being...
Forum: Coders. General 22 November 2017, 12:14
Replies: 188
Views: 16,528
Posted By coder76
Yes, I think we all agree that an A1200 is needed...

Yes, I think we all agree that an A1200 is needed to get a decent Metal Slug port. And also an accelerator board with lots of fast ram.

With 16 color dualplayfield you can actually get something...
Forum: Coders. General 14 November 2017, 15:39
Replies: 188
Views: 16,528
Posted By coder76
Look up Neo Geo specs somewhere: ...

Look up Neo Geo specs somewhere:
https://wiki.neogeodev.org/index.php?title=Sprites

Neo Geo has a limit of 381 sprites per frame and 96 per scanline. Neo Geo sprites are all 16 pixels wide and...
Forum: Coders. General 12 November 2017, 16:23
Replies: 188
Views: 16,528
Posted By coder76
The single buffer method will not usually work...

The single buffer method will not usually work even for games that run in one frame, unless you are able to race down before the beam when drawing. But screen drawing can't usually be done like that,...
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