Crazyace

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The WinVICE C16 and Plus/4 emulation is nowhere near accurate at the moment and it stuffs up a lot of things; for demo watching especially, get hold of YAPE instead. Thanks. I like the 128 colour chunky mode shown on the plus 4 - that's quite cool - although the CPU seems to slow down more than the atari during the demo

Some of those are quite nice - but some are a bit disappointing... but that's on a machine designed in 1984 - which would be a different Atari v Commodore comparision. Most DFLI pictures are converted, the dithering and so forth is down to that process; throw a decent editor at a good artist and it'll do something pretty spectacular... For the Plus/4 to Atari comparison, the A8 can do 80 colours a scanline from 121 in 320x200 mode, can overscan vertically with ease although horizontal is a more tricky, the CPU is about the same speed on both and the only real down sides are the lack of hardware sprites and TED sound... If only there had been sprites - ( or if the C64 had the extended pallette ) there probally wouldn't be any comparisions... As an aside I tried to run the chaos demo under WinVice, and it stops... What effect isn't being emulated?

Some of those are quite nice - but some are a bit disappointing... but that's on a machine designed in 1984 - which would be a different Atari v Commodore comparision.

Full screen curtains wouldn't be impossible on the c64 - just more difficult. I'd only use sprites for the edges of the curtains, and change the colour/character cells - as that way I wouldn't have to use any interupts or multiplexing, and the curtain edges could be more detailed. This is reaching - especially as there are effects ( The 256 colour per pixel 80x100 GTIA+ mode ) that are impossible to replicate on the C64. ( Funny - I think the +4 might be able to do it - but that has no sprites at all )

I just looked around and the universe still has IN FACT more than one dimension! I sense your bias (and some others') toward your C64 at the cost of establishing the truth. There's also a Y-axis and Z-axis and time, originality, etc.. Ever heard of these elements of the universe? If I only looked at the height of sprites, perhaps I will conclude the opposite. If I had to move sprites in the Z-direction, well then having 2X,4X zoom is better than just 2X so Atari wins there as well. If I had to look at the time factor, 1.7897 timer vs. 1Mhz timer on C64. Well, Atari would win there as well. If I had to look at originality, well Atari came out with sprites first. I can show you sprite examples (if you did not read about them already in this thread or others) that will not work on C64. So don't say stuff like in your post #347: "C64: 64K memory, way better sprites, 16 colours/line, 320pixel scrolling and colour" It's not WAY better. I rather have vertically high sprites for some applications. 16 colors/line is also available on Atari and even more colors as well. You can also multiplex sprites horizontally if the shapes are taken from same PMBase. 64K memory is not a big deal vs. 62K on 800XL. Brilliant The 64k memory comment for the C64 was more about every single machine having 64k ram - my 400 only had 16k , and my first 800 came with 16k that I upgraded to 48k. There were a lot of A8 games that had to use less memory to maximise the audience. Even with the XL there were the 600XL and 800XL - only the XE's gave 62K min. I've been programming the 8 bits for a long time - and I like the PM graphics, but as a programmer there's no way I'd prefer them over the C64 sprites - even given the stupid limitations . ( The Z direction is the most stupid thing ever - it's like saying the 2600 players are better than the A8 or C64 because you can set 3 copies ) The Atari advantages come with the faster processor and the bitmap modes - look at Wayout on C64 and A8, the Atari version looks a lot smoother. If anything, I'm biased towards the A8... but although I'm biased I cant really accept complete fiction

That's the thing missing with the 8 bit atari's. The Amiga had revisions to it's basic chipset to improve things. The ST had hardware revisions as well ( MegaST , STe, falcon ) - even the c64 had the c128 But all of the Atari revisions never changed anything with Antic/GTIA

I dont know how anyone can argue that the Atari sprites are better than the C64 sprites - it's just not true.. ( Setting double width on C64 - so that the res is the same ) C64 - 8 sprites, each 24 pixels wide A8 - 4 sprites, each 8+2 pixels wide or 5 sprites, each 8 pixels wide ....there's no comparision - the C64 wins the sprite award with ease

Driving GTIA directly only allows you to set players and missiles. The playfield is only supplied by the AN0-AN2 circuitry ( and Sync as well ) so there isn't actually as much functionality exposed as the original TIA

The definition is a bit pointless really. Antic is just one part of the 8 bit Atari. I was thinking that one of the things that's great about the C64 is the 64k memory... Imagine if it had been released as the ultimax , with all of the potential locked up by the measly 4k ram If the 8 bits had been designed for 16k ( rather than 4k in the low end ) I doubt that some of the 'lower' res graphics modes would have been included at all in Antic as they could easily be reproduced with more complex display lists. To sum up: C64: 64K memory, way better sprites, 16 colours/line, 320pixel scrolling and colour A8: Larger colour selection, faster CPU, better scrolling of bitmaps It's a wonder that anything is better on the A8 at all - given the fact there are 4 years between the machines. I sometimes wonder - given that the A8 was meant to be a 2600 followup - what would have happened if it had been released as a console in 79/80.. The Intellivision would have had far more trouble going against a '5200' at launch - and maybe b/c with 2600 games would have been more important for a console release ( rather than a computer that would be 'repositioned' later

I tend to just think of Antic/GTIA as being the display processor. I guess you could connect a GTIA directly to a 6502 in some way - but it wouldn't be that much better than the original 2600

The user comments seem to be a bit random - to say the least If the FCC regs weren't so tight at the time the 400/800 might have been a bit cheaper to make - rather than having insides constructed like tanks

For the Pacman demo running 4 ghosts + Pacman is taking most of a frame at the moment ( at 60Hz ) This is not fully optimised code, and implements a mask/data sprite, rather than simple Xor. 5 sprites - 16x16 pixels each, renderer as 20x16y for horizontal, and 16x24y for vertical. Real H/W sprites are way,way better

The Atari has 2 graphics chips. One that has a 16 Bit Adress bus and one that has 8 Bit registers for colour counting... The colours are only limited by the GTIA. That's got almost nothing to do with bandwidth though... The Char fetch would not be necessary if they were stored in the external memory. Antic only was needed for down-compatibility to the older machines and for extensive screenusage. Only some command was needed then. a command that tells "E-GTIA" -> now compatibility mode -> now extended mode... The extended mode could be controlled by ANTIC's DMA. The Screendata is pre loaded and the DMA controls what's happening on the screen. There were two ways to store the screen data into the external RAM 1. Simply Data polling via writing into registers (good for Business use and 80 coloumns) 2. An "E-GTIA" Mode that can be loaded through a special command via ANTIC's DMA That's a really complex scheme though - why have external memory when the internal memory is fast enough If you were redesigning the XL(or XE ) you could just use faster memory - colclk/1.5 rather than 2 would give you a lot more clock cycles for antic dma during a line. The changes I'm thinking of are probally more limited, because I thinking what could have been put in for use in the 800XL ( or 130XE ) by Atari at that time - for the price they wanted to sell the machine

In bandwidth terms the Vic is better as it has a 12 bit bus - that's 50% more. Even if a 16 colour mode took most of the b/w it would still be usefull for graphics. 80 column text would be extremely difficult ... If you spread the character fetch you could run 80+10 fetches per line though - widescreen would be 96+12 which would probally be every possible cycle 80+16 fetches woud fill the char buffer in five lines - leaving 3 lines with a little more cpu activity

? GTIA has enough free registers and adress range to bind a Radeon 4500 series chip without changing the design philosophy. All necessary was the sparated Screen RAM and some added logics to the GTIA. No changes on Antic or the System-Bus were needed. Now that's a stupid idea - binding a seperate video chip in via the GTIA ports would neglect the reason for Antic - You would actually end up with a design similar to the TI/MSX/Colecovision etc. For a redesign by Atari for XL or XE - changes to GTIA/Antic would be way easier. ( It's not such a stupid idea if you're trying to patch in another board to a fixed design - like the videoboard )

Yes, comparing a8 to Amiga is a bit pointless in this thread The separate colour ram in the c64 is a real strength - it would have been difficult to add to the a8 without completely changing the design philosophy..

When does what data get fetched on the A8? The A8 performs two memory cycles in the time required to display each character, but from my understanding it does not interleave memory cycles with the CPU the way the C64 and Apple II do. Are the bytes required for each line fetched in a burst, or what? It would seem the A8 should have enough memory bandwidth to at least handle 320-wide 4-color graphics or 160-wide 16-color graphics. Antic already fetches 80 bytes in character mode lines ( not every line though ) - so it could easily handle 160x16 colour with no change to the memory system. Given the Antic architecture - 16 colours pallete rather than a colour ram would be more suitable.. Make 16 palletes .. BK, PF0 - PF3 ... [ PF4,PF5,PF6 ] 8 players ( no missiles ) P0 - P3 .. [ P4 - P7 ] For mono text select colour pairs, rather than colour+BK For 4 colour text select ) BK/PF0-PF2 and PF4-PF6/PF3 - two groups of 4 colours, rather than 5 and 16 pallette entries for GTIA modes It would be a cool design maybe some FPGA wizard could implement it... ( or maybe Curt knows of some hidden prototype already )

That's really nice - I think it actually looks better than the c64 pictures because of the extended colour range

That's how I'd change antic if I wanted to add c64 style colour attribs - Are there any plus4 equivalents to FLI pictures around? 80 columns wouldn't be the main aim, just one possibility - especially as Atari were already offering an 80 column solution. ( The 800 was aimed at home computing, not just games - even though games were a primary use ) For the Amstrad - a faster z80 would have helped ( and better scrolling or even sprites at the launch ) I dont know what happened inside Atari - but the 1200XL didn't actually offer much over the 800 apart from the extra 16k Atari were very cautious about their products in some ways - after all Commodore went from the Vic20 to the C64 in a much shorter timespan than the 400/800 -> 600XL/800XL

I didn't know that - I guess the c16/+4 didn't have the seperate colour ram? 80 columns would have been useful as other machines had them - the BBC micro offered 80 column in 1981/1982 , and the Amstrad machine also had 640/320/160. Also the AppleIIe was out in 1983 with the 80col card and double hires graphics. It would have been great if a redesigned Antic/GTIA made it into the XL machines ( or even the XE machines )

That's a major change - especially as antic already reads 80 bytes on some lines - without any extra ram, just the cost of slowing down the cpu a lot, it would be possible to run hires or 16 colour lowres. There's only 112 cycles - so if a charmode was needed the charcodes would have to be read in over multiple lines ( and widescreen would have to be curtailed.. )

This is almost worth a seperate topic to discuss what could be changed in Antic/GTIA to give better graphics with zero change to the rest of the system ( I'd go for a 80 cycle graphics mode to give 640x2, 320x4 or 160x16 , and 8 bit missiles with seperate color registers )

Given the tech - It should have been easy to make the missiles 8 bits wide ( and give them 4 extra pallete entries - Then the GTIA 10 mode could be 13 colours If Antics internal line ram could be doubled it could be loaded over 2 lines - one for character, and one for an attribute A much more useful 160x100 16 colour background could be implemented by using the antic internal character buffer to hold 40 bytes to combine with the standard 40 bytes read Hires and C64 size sprites would have been great as well but unlikely given the design coming from the VCS

Thanks for the answer - I found about about the $3fff property after reading a bit more. So if the only way to use the borders is with sprites then this is a weakness against the 8bit atari. ( Of course in demos - where the level of coding is heroic, to say the least, the C64 pulls off some amazing effects )