Crazyace
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Posts posted by Crazyace
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No problem,
GPRIOR0 and 23 colours per scanline ( scrolled ) would be a big advantage to the A8 apart from it having quite stringent limitations - The best image I saw was the Tetris game in the other thread. That's why I treat it in the same way as the 48 colour/line Spectrum 512, which is also limited , but has quite an impact.
( It might be interesting to try to reproduce a particular image if you've got something in mind though )
I've seen some of the Photochrome pictures that look pretty amazing, but I guess they are in the same class as the hip mode pictures on the A8 - they are using 2 frames to get effectively 16 shades rather than 8 , but the flickering seems a lot less noticeable than some of the A8 pictures. I guess that's because the A8 is trying to mix a base colour with a brightness , but the ST is just trying to flicker between two consecutive brightnesses to suggest an inbetween value.
Mr Robot is a game that I couldn't see any problem with replicating on the ST though, so that's why I raised it. ( The character animation might seem complex, but there's nowhere like a full screen animating on any of the levels )
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Well, your attention to detail is the thing that will make it a great version of the game
- I had a look at the PC Engine version, and if you made a version with no background at all it would still be amazing.( I keep wondering what the XL would have been like if it had been designed with Beeb style components ... more bandwidth, 160 pixel GTIA modes
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That's a lame argument to claim gaming world doesn't use it. I am discussing which hardware aspects are superior-- whether some application uses it or not is not my problem. Most games don't even use GTIA modes at all what to speak of translucency effects and scrolling them. You can't show 16 shades nor do you have the bandwidth to do the scroll/overscan for 16 colors what to speak of >16 colors.
Whatever, You dismiss the 640 by 4 colour and 320 by 16 colour pixel screen modes on the ST as any kind of advantage, and concentrate on the 80 pixel by 16 colour scroller.
As I said - there seem to be demos that already do this on the ST, so I don't feel the need to make another one.
I never said those games were impossible to do on ST, they are better on A8. You keep repeating the samething over and over again. Yes, ST has higher resolution and better processor but lower resolution modes are also useful and shades are also useful. Yes, TEXT modes are useful as well. ST display is inferior when it comes to games relying more on motion rather than hi-res static imagery. And even static imagery that requires shading doesn't look so hot on ST. If ST had a 256 color A8 palette, its imagery would look more like Amiga's (using high resolution). Just having high resolution doesn't make the display superior else you can say CGA with 640*200 and 320*200*4 has better display than A8.
Please back this up? Mr Robot doesn't use 16 shades - it's completely non GTIA. What are you comparing a static ST image with? Everything I've seen looks technically way better than the A8 best. ( And why are you bringing CGA into it again - the discussion is A8 vs ST )
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Have you considered using bitmap rather than character mode? ( One of my favorite A8 games is bandits - which pretty much did everything in bitmap mode - although it had a rather cavalier attitude towards framerate at times )
( Just thinking about Zalaga on the BBC as a good shooter - nowhere near as complex as galaga88 though )
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Owned:
ZX80
Spectrum
Atari 800
C64
Amstrad CPC664
800XL
QL
4160STe
Amiga 2000
Various PC's
7800
Net Yaroze
PS2 linux
PS3 linux
Saturn
Dreamcast
Xbox
Gamecube
Wii
Xbox360
Retro ( now ):
Plus4
2600
XE GS
130XE
Jaguar
1040ST ( not tested, no room to set up on desk - and emulators pretty good )
Colecovision
SuperCassetteVision
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It's readable but I wouldn't want to be writing letters all day in black on white text etc over a PC monitor which has at least 2x the native resolution on the CRT tube
It's all a long time ago now
- Once I moved on to coding on a host PC I switched to using Brief in 132 column mode ( I think on some Cirrus Logic video card? ) -
Actually I find that I haven't used my Saturn or Dreamcast for quite a long time now. Most of the games I'd really like to play ( enough to set up the machines ) are light gun games, and both my main TV - and the TV that my kids use in their room, are LCD's which dont work with light guns
All of the old CRT monitors I used to use for gaming have gone, and with them the era of gun games ( Point Blank, Time Crisis, Virtua Cop, House of the Dead - all just gathering dust now )
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Problem is in 80 columns regular CRT dot pitch/native resolution is insufficient anyway, and well 320x200 doesn't need RGB as you put it, using an ST or Amiga via S-Video or composhite [not a typo] video is perfectly adequate for gamers (and 320x200 is too low for serious applications anyway) The reason why you can't read 80 column txt on an ST is not because the converter is low quality, but the TV input technology itself.
I've never had any problems reading 80 column txt on any TV I had via RGB ( I had one of these ( Ferguson mc-01 http://www.worldofspectrum.org/showmag.cgi?mag=YourComputer/Issue8411/Pages/YourComputer841100192.jpg ) that I used with my 800(via s-vhs) and my ST for a while before I got a Trinitron RGB/Composite monitor. ( Like this one http://upload.wikimedia.org/wikipedia/en/thumb/3/3a/Trinitron_computer.JPG/800px-Trinitron_computer.JPG )
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I can scroll a GPRIOR mode 0 as well as an overscanned screen Graphics 9 screen w/translucency. These are a couple of examples impossible for ST.
Good for you
- I'm glad the rest of the gaming world took to graphics 9 so much Several demos seem to scroll overscanned full screen images with more than 16 colours, so I wouldn't say it's impossible though.
You're speaking rubbish. Don't compare with quarter screens then. If you think low-res modes are not needed then be prepared to replicate pixels and lines to mimic the A8 modes at CPU cost. Of course, some cannot be mimiced, but that's your problem. Games I mentioned won't play any better with higher resolution; in fact, they will most likely slow down or perform worse on ST with the higher resolution. So don't say ST wins just because it has higher resolution. Text modes are also significant. You can't paint a text screen in the same time or less as an A8 doing it. In fact, I can repaint any of the A8 text modes within the VBI. More time penalty for ST just like scrolling.
Text modes are really useful - I'm not sure I'd include Mr Robot as something impossible to do on the ST though.
But you can't reproduce 320x200x16 colours per pixel in any way possible on the A8 - ( and forget 640 pixels ). On the ST I can reproduce any display on the A8 - it may just take more time. Therefore I say that the ST display is superior.
Even with GTIA - I can happily say pallette of 512 colours is better than pallette of 128 colours, as the only 16 shade modes aren't palletted.
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It's more colors and less shades. So it's a trade-off since now ST has problems representing some of the gradiences and shaded images of A8. So not a clear cut win for ST. Humans perceive luminances more than colors-- just study the TV signal construction. So don't just declare ST wins. I rather have more shades. As I stated before, I rather have 64 shades and 4 colors.
The pallette on the A8 only has 8 shades, so it's a fair comparision 512 palletted colours vs 128 palletted colours.
So given A8s fast I/O using joystick I/O, that also has to be put into the comparison not just "oh, now we can use the parallel port."
Feel free to put abuse of joystick port as an A8 advantage
- I won't argue with your opinion on thatThat's the biggest bullcrap you have written thus far. I can also say parallel ports for laplink, ZIP drives, etc. is utter abuse of the parallel port; you need help. I suppose putting in bidirectionality in the joystick ports was a big mistake or some accident by Atari. SYNC is ABUSE of video circuit on ST, but doing I/O is perfectly good use of joysticks as PIA wasn't just meant for reading digital joysticks.
I'm not arguing with you? - so why are you continuing. I'm quite happy with the advantages you've already given for the extra use of joystick ports.
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It sound's pretty flexible ( mind you the A8 OS was always pretty cool in the way device drivers worked. ) - I never looked at the internals of gem/drdos though - but don't they have similar concepts?
( For games on both machines it was just boot sector then take over the hardware
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Having a full system bus connector ( or even r/w ) on the cart would have been great - I don't know why Atari didn't - maybe the idea was that all of the interfaces were already present on the machine. It was annoying having to 'spoof' the write for Replay.
Did the PBI give you dma access though? ( like the Commodore REU's did )
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never thought that the ST is superior to be honest... in terms of flexibility of the hardware (gfx chip, sound f.e.)... ok... games were good but as coder when I touched the machine (but never cought my attention too much)...
The Amiga had all of the cool hardware
- I think I felt a bit more warmly about the ST than you, as I'd just been programming for the QL ( which was pretty slow - but at least had a nibble screen mode.( Also the Amiga 1000 was way way more expensive than an ST )
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Conclusion (not to be taken separately from the rest of the post): XL/XE is a more open architecture than ST, both hardware-wise (connectors) and, even more, software-wise (plug-and-play mechanism, known as Parallel Bus Interface, absent in ST). So in this point XL/XE seems better than ST, eventhough it is older and therefore inferior in gfx and processing power.
The 400 and 800 didn't have this capability though? ( and I guess you could implement a rom device on the ST via the cartridge port if you wanted ) so I expect what you're comparing is the XL PBI to something like the internal bus connector in the Mega ST machines?
It's definitely more flexible than the DMA interface though.
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Technically obviously the ST is more superior, but I way way way prefer the 8-bit.
The OP is right, the ST just doesn't feel the same as the 8-bit at all, it really doesn't seem as though they are related to each other.
The ST just kinda feels souless in comparison to the 8-bit, like it's more like a traditional bland computer.
When I was young, I was sucked in by the flashy graphics of the ST, and sold my 8-bit to get one (I had in mind that I'd buy another 8-bit when I was able to).
About a week later I totally regretted it, the games on the ST just weren't as fun as the games on the 8-bit, they weren't even the same. In fact to this day there's not really many games that I like on the ST.
I've got games that I loved on both platforms - from Drol and Bandits on the A8 which hardly use any special h/w , Preppie and Rally Speedway , through Lemmings and Dungeon Keeper , Kick off ( and Sensible soccer ), Captain Blood and Another World
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If it's not S.Y.N.C. based, let's see it.
It's not dodgy; it works consistently. And the code above proves that the PRIOR 0 mode is DEFAULT. I didn't have to alter the PRIOR register to get the ORing to take place as the default setting of location 623 is 0. If it were dodgy, you would think the OS would have put some other value than 0 into 623 at startup. I have read other things regarding SYNC (for ST, CGA, and other machines) and CGA was an example which modified the frequencies of monitor to get new graphics/text modes (or mixed versions) that led to the damages of many monitors.
What is S.Y.N.C ? I've heard of sync scrolling ( short for synchronisation I guess) - but not S.Y.N.C
Please only concentrate on ST ( or A8 ) in this topic - you keep on bringing up CGA for some reason - maybe you're getting confused about something completely different on that card.
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I wasn't going to reply, but I guess I did invite the response
Sorry, but A8 graphics modes are full-screen. So whether A8 does 320*200 or 80*200 or 40*25, they are all full screen (and can be more w/overscan). And don't forget the mixing of modes like doing GTIA + Gr.8 on one scanline.
A8 graphics modes are also lores - but I was being pedantic about the quarter screen
, so I'm not going to use that argument as an advantage for ST.Does mixing modes work with scrolling as well? ( In software it's a bit trivial for the ST - but I've never looked at whether you could switch 320-640 mode in the middle of the screen )
( Also GTIA on the A8 wasn't launch, maybe I should compare an ST model with blitter for timings )
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STe was when people already went for Amiga/PCs. GTIA was when 8-bit was still peaking and natural upgrade (backward compatible). If ST had been compatible with A8, nobody would be debating this issue.
I was thinking MegaST for blitter , but you're correct, most A8 machines had GTIA, - and all of the scrolling was present on CTIA only. I'll stick with code samples that only require a standard 520ST.
Sorry, if you are going to list specific modes, A8 will win. A8 has a lot more graphics modes/text modes than ST. A8 can't do 640 modes but ST can't do most of the A8 modes of >16 colors. That's why you have to replicate pixels/lines to simulate those modes; otherwise I would have listed those modes as a separate advantage in my list. So Mr. Robot, Boulderdash, Joust, Pac-Man, etc. are 160*200 but the objects are well-defined at that resolution and full-screen.
Rubbish - ST wins because it has higher resolution, higher colour modes. ( and what A8 modes are >16 colours - nothing in any of the hardware manuals I've got? )
( I don't actually understand what your Mr Robot etc point is about though - can you clarify? )
ST has 512 colours, better than 128 for launch A8
Cut the "for launch" crap. ST not having RF modulator is worse than some 400/800 not having GTIA chips. 400/800 can pop in GTIA chip w/o soldering; you can't pop in a RF modulator in the ST. And I didn't put "lack of RF-modulator" in my list. Nor can you pop in a chip in the ST and give it more shades.
512 colours better than 128 has nothing to do with an RF modulator? - what is your point?
Even with GTIA - I can happily say pallette of 512 colours is better than pallette of 128 colours, as the only 16 shade modes aren't palletted.
RGB video is not better than A8. A8 was targetted for TVs so it doesn't need the RGB. ST needs the RGB video (making it more expensive) in order to show it's advantage of higher resolution.
Rubbish - RGB video is a better standard, ( and in Europe it was in a hell of a lot of TV's , with SCART/Peritel eventually standardising it )
So given A8s fast I/O using joystick I/O, that also has to be put into the comparison not just "oh, now we can use the parallel port."
Feel free to put abuse of joystick port as an A8 advantage
- I won't argue with your opinion on that -
I'll take a look at the code once I get some time. It's theoretically impossible to copy 4 planes for a full screen given the 68K bandwidth limitations.
You can stop speculating that it can be done in less than 10% of the cycles.
No problem, I wrote it for my info more than anything else, and then posted it so at least there would be something to back up my claim.
I'll see if I can get the Battlesquadron first level to assemble ( I couldn't fully recover one of my data discs ), as that uses vertical smooth scrolling ( 16 colours ) with roughly 20 scanlines worth of time. - Not speculation, but actual figures for a game.
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ST has video starting address at 256-byte alignment so unless you are doing some weird tricks, even vertical scrolling would be troublesome. Compare with EGA which has video starting address on BYTE alignment.
Yup - it's using wierd tricks, but they work
To me, Sync scrolling is just as valid as the prior 0 hacks on the 8 bits, something that relies on an undocumented reliable mechanism in the hardware to give a boost to the machine capabilities.
Sorry, but PRIOR 0 is GTIA doing its normal operations and not a big discovery-- just type something like:
POKE 706,122:POKE 53263,255:POKE 53250,128
It has nothing to do with playing with video frequencies which has proven in history to cause problems/damage (i.e., CGA).
It's very dodgy, as inside the chip you're driving two outputs at the same time into a single input. I guess it just luckily works because it's NMOS ( Curt can probably correct me if I'm wrong )
Please also read up on how the sync scrolling works - it doesn't actually change the frequency going to the monitor - it just confuses the shifter into displaying more valid infomation per line - just like wide playfield on A8, but via a hack.
( Not sure about what CGA has to do with it? only talking about A8 and ST here )
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Just started looking at your code. Why do you have: "movem.l (a5)+,d0-d7/a0-a4, movem.l do-d7/a0-a5,0(a6)"? Is this a typo or purposely screwing with the stack in which case it would affect the cycle count...
I meant screwing with (a6) by storing a5 on it since you have cycles @8*13.
Sorry, those two lines aren't actually used anywhere - I was just sketching different routines before deciding which one to actually use
( I think I started with movem.l (a6)+,d0-d7/a0-a5 ; movem.l d0-d7/a0-a5,-(a7) - as I had a crazy thought about abusing the stack as a temporary register )
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Emulation , and changing TV standards will eventually kill off old consoles. After all in a few years TV's wont have analogue RF inputs, so they won't be able to tune the really old consoles in.
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ST has parallel floppy disc, better than A8
And? This is also possible on Atari 8bit. when you make a list, you should not mention things that both systems can.
When you compare A8 and atari ST you must compare 'bare' systems. So Atari ST without floppy (520 ST).
And about harddrive. OK atari 8bit can hookup harddrive on Parallel Port and Cart Port, which is not DMA, but really fast. Fast enough I'd say.
I should have realised that making a list was a mistake.... but it was so tempting 
Even the 520ST still has a parallel floppy interface - just no drive built in.
The ST HDD interface is better because it's faster, dma, and has no low cpu cost. ( Did any of the HDD interfaces actually exist back in the day - when I was using the A8 the happy chip and US doubler were the 'cool' addons, and the cartridge port was for Mac65 ) I've seen the SIO2SD stuff ( which is still slow, but cool ) and I use the SIO2USB now - but I haven't got much knowledge about internal/cart mods.
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Hmm, I remember you mentioning this before, but I got a different impression in another discussion here: http://sega-16.com/forum/showthread.php?t=8473
SMS, they set a square channel to a high playback rate and modulate the volume. But the volume isn't linear and since it's low of granularity steps, it's noisy. Another method is to combine this process on the three square channels so that the mixing gets more "in between values". There's the problem that you can't change all volumes fast enough, so that introduces some noise/artifacts. And there's the PWM method. You set the channel to high frequency and turn the volume on(max)/off to produce PWM waveform. Problem with this method is that it needs to be really fast and with precise timings. Pretty much all the methods require almost 100% processing time for the timed-code playback routine. The method that uses all three square channels sounds the best.Then again, that was in specific context of the SN76489 PSG, not the AY/YM2149, so it might be different. I'd though the 76489 used logarithmic based volume control as well ("stepped" volume rather than linear), but int hat case it's 4-bit (16 volume levels), so the YM2149 might have more control there.
On the ST it was quick enough to do in an interrupt. The normal per voice volume level was {1,sqrt(1/2)}*{1,1/2,1/4,1/8,1/16,1/32,1/64,1/128} so the dynamic range was there, and the tables were precalculated to approximate a linear curve using 3 voices ( sometimes two )
I never looked at PWM for improving the signal capabilities as such, only to multiplex voices at one point ( and I've got no idea where the code is, it's probably on one of my old replay disks )
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Plus, I've got more than my hands full with A8 stuff, and then there's the small matter of just very suddenly having fallen in love with the Coco3 which might see things go even more not to plan if I don't control the urges to play
I'm sure I saw some sync scrolling stuff floating around on www.atari-forum.com/ forums.. And also there's some thing I recall about being able to use the DMA chip to perform 1 bit shifts as well, or some such guff, but it was probably hot-air, just like some of the industrial level hot air claims being made in here as well
Really I'm just watching this thread only for it's enormously fun car crash value and entertainment
Long may it run!I should be programming SPE stuff at the moment ( although I think it's safe to say that it's not really required this week ) - and I've got random A8 and 7800 and Jaguar stuff in my coding folder to play with.
I saw the Coco3 with the Donkey Kong and Pacman games, and the recent 256 colour pictures, but it's NTSC only which is a bit of a let down... so I'm managing to resist it.. ( and one day, maybe my Pandora console will actually arrive, and I can run the A8, C64, ST and Amiga emulators on a DS sized machine with a keyboard )
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I thought they were like some of the Pern dragons in some ways
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You'll never see me making claims about a machine being inferior just by looking at a few games. In fact, I argued in reverse for the most part-- that it's better to look at capabilities of the hardware. I said Boulderdash and Joust are inferior on ST. But I'm not going to generalize from that that the machine is inferior. It's the reverse-- since I know ST takes a big hit for scrolling (via cycle calculations), I look for examples where that big hit takes place. It's more deductive logic than inductive.
Well, on a like for like case - If I scroll a 16 colour 80x192 line screen on the ST it will take less than a quarter of the cycles ( It will also only be quarter of the screen, but that's a limitation of the A8 )
I should compare 320x192 2 colour as that's the only resolution that matches between A8 and ST.
( Also GTIA on the A8 wasn't launch, maybe I should compare an ST model with blitter for timings )
So for me:
ST has 640x200 4 colour mode - better than A8
ST has 320x200 16 colour mode - better than A8
ST has 512 colours, better than 128 for launch A8
ST has faster processor - better than A8
A8 has scrolling, better than ST
A8 has 4 sound channels, better than ST
ST has parallel floppy disc, better than A8
ST has RGB video, better than A8
ST has DMA harddrive, better than A8
ST has 512k ram, better than A8
... and so on, can't be bothered making a longer list ....
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Atari 8bit is superior to the ST
in Atari 8-Bit Computers
Posted
Having scroll registers would have been great though. The STe was just a little too late - by the time it came out developers couldn't ignore the base ST model - so any support would have to be extra work.
Personally I'd have been happy with a word addressable screen base - as that would solve the problems for vertical scrollers at least.
( I wonder what the chances were of a ~10MHz 68000 at the time - you could use the same crystal found on the NES , /2 for CPU, /6 for 3.58 NTSC colour , or slightly different crystal /5 for 4.43 PAL colour )