AtariSt hardware capabilities???
category: general [glöplog]
I have got the latest SainT and watched some more famous Atari demos. They all look very Wow! The older clasic ones were not that trackmo, but reminded me the CPC ones with their cool onescreeners and menus to choose parts and stuff. Some of them seem to copy hardware effects from Amiga. Do they make that with software or hardware tricks? I have heard that Atari had much fewer hardware effects than Amiga.
What does it have and what not. Hardware scrolling/sprites? Horizontal/line splitting? Vertical splitting? Raster interrupts? What are the hardware tricks that Atari do have and what are the ones that it doesn't?
Btw,. does the Atari has a bitplane logic like in Amiga? (Which makes it very hard to do pixel per pixel bitmap effects as far as I know) Or is it easier to do software effect on Atari than in Amiga? I think I have seen quite many great software effects there, never been seen in old Amiga..
I have an Atari here but it's sleeping. Have to get the monitor from my brother till times :(
Optimus
P.S. Did you know btw, that Chaos/Sanity had recoded/converted the Elysium starwars scroller in an AtariSt demo?! I think the demo was called Just buggin with a Ninja moving around a level and opening door demoparts, but I can't remember for sure... (I don't know which demo is which)
What does it have and what not. Hardware scrolling/sprites? Horizontal/line splitting? Vertical splitting? Raster interrupts? What are the hardware tricks that Atari do have and what are the ones that it doesn't?
Btw,. does the Atari has a bitplane logic like in Amiga? (Which makes it very hard to do pixel per pixel bitmap effects as far as I know) Or is it easier to do software effect on Atari than in Amiga? I think I have seen quite many great software effects there, never been seen in old Amiga..
I have an Atari here but it's sleeping. Have to get the monitor from my brother till times :(
Optimus
P.S. Did you know btw, that Chaos/Sanity had recoded/converted the Elysium starwars scroller in an AtariSt demo?! I think the demo was called Just buggin with a Ninja moving around a level and opening door demoparts, but I can't remember for sure... (I don't know which demo is which)
Atari Hardware:
CPU 68000 8 MHz. Amiga has 7.1xxx Mhz. since pixel clock and cpu clock are synced on both computers, atari pixels are smaller. since both have a 320/640 resolution, atari has a larger border. (yes, that's why amiga has that strange clockrate)
Sound: 3 square + 1 noise + 1 envelope. thats much less than a C64! no filter, no sync, no other waveforms and (!) no pulsewith modulation. to get something cool out of an st, some people have programmed the cpu-timers to high interrupt rates and resetted a waveform, emulating pulsewidth modulation. this was often called "sid".
display: the graphic chip is called "shifter" because it does nothing but shifting bits. you can set the display start address, but not the lower 8 bits (therefore smooth scrolling is impossible). you can switch 50 and 60 hz and 16 colors 320 pixels / 4 colors 640 pixels / 2 colors monochrome monitor output. you can't change the border. you can't smooth-scroll. you cant even scroll by changing the display start address (lower 8 bits are missing). you can display a picture. in 16 colors, bitplanes are word-interleaved, not like amiga line or screen interleaved. 16 colors are out of a palette of 512 colors. oh, no blitter for classic ST demos. oh, i forgot, you can't change the display address each line, the register is latched each frame.
sync-coding:
you can synchronize the cpu to the graphics hardware and change the screen-resolution each line. this may make the shifter "forget" to start the border. this make make lines longer. some early atari demos needed 21 (or so) rasterlines, some of them with open border, others not, to waste some bytes. these lines are not displayed, but by using special mixes of these lines you can "regain" the missing 8 bits of the display start address, allowing "soft scrolling" (together with other tricks).
preshifting:
now you can scroll by 1 pixel in y and 16 pixel in x. to scroll smoother in x, you need to store your image in "preshifted" versions. ususally 4 versions are good. if you see something scrolling SLOWLY by x you can be shure that it took a lot of memory or very clever coding.
must see demos:
- Dark Side of the Spoon
- Ooh Crickey Wot A Scorcher
(oh, i am an ULM/LostBoy fan! I saw "Dark Side" once at a local meeting and that was the day when I stopped calling ST-users "Lamer".)
classic atari style:
a character runs through some kind of jump&run game entering doors that lead to the effects (called "screens").
i converted some of my amiga effects to st
- the fullscreen sine scroller (sanity is dead, woc)
- the elysium starwars scroller
- the arte rotzoom
and to falcon
- a fullscreen rotzoom
- the tilting waving fullscreen rotzoom (roots)
and maybe some i forgot.
maybe some of my statements are not accurate since it's ten years ago and i never did sync-coding myself.
(optimus always knows a new question to ask..)
(too much text. must work.)
CPU 68000 8 MHz. Amiga has 7.1xxx Mhz. since pixel clock and cpu clock are synced on both computers, atari pixels are smaller. since both have a 320/640 resolution, atari has a larger border. (yes, that's why amiga has that strange clockrate)
Sound: 3 square + 1 noise + 1 envelope. thats much less than a C64! no filter, no sync, no other waveforms and (!) no pulsewith modulation. to get something cool out of an st, some people have programmed the cpu-timers to high interrupt rates and resetted a waveform, emulating pulsewidth modulation. this was often called "sid".
display: the graphic chip is called "shifter" because it does nothing but shifting bits. you can set the display start address, but not the lower 8 bits (therefore smooth scrolling is impossible). you can switch 50 and 60 hz and 16 colors 320 pixels / 4 colors 640 pixels / 2 colors monochrome monitor output. you can't change the border. you can't smooth-scroll. you cant even scroll by changing the display start address (lower 8 bits are missing). you can display a picture. in 16 colors, bitplanes are word-interleaved, not like amiga line or screen interleaved. 16 colors are out of a palette of 512 colors. oh, no blitter for classic ST demos. oh, i forgot, you can't change the display address each line, the register is latched each frame.
sync-coding:
you can synchronize the cpu to the graphics hardware and change the screen-resolution each line. this may make the shifter "forget" to start the border. this make make lines longer. some early atari demos needed 21 (or so) rasterlines, some of them with open border, others not, to waste some bytes. these lines are not displayed, but by using special mixes of these lines you can "regain" the missing 8 bits of the display start address, allowing "soft scrolling" (together with other tricks).
preshifting:
now you can scroll by 1 pixel in y and 16 pixel in x. to scroll smoother in x, you need to store your image in "preshifted" versions. ususally 4 versions are good. if you see something scrolling SLOWLY by x you can be shure that it took a lot of memory or very clever coding.
must see demos:
- Dark Side of the Spoon
- Ooh Crickey Wot A Scorcher
(oh, i am an ULM/LostBoy fan! I saw "Dark Side" once at a local meeting and that was the day when I stopped calling ST-users "Lamer".)
classic atari style:
a character runs through some kind of jump&run game entering doors that lead to the effects (called "screens").
i converted some of my amiga effects to st
- the fullscreen sine scroller (sanity is dead, woc)
- the elysium starwars scroller
- the arte rotzoom
and to falcon
- a fullscreen rotzoom
- the tilting waving fullscreen rotzoom (roots)
and maybe some i forgot.
maybe some of my statements are not accurate since it's ten years ago and i never did sync-coding myself.
(optimus always knows a new question to ask..)
(too much text. must work.)
Wow... lot's of infos! Thanx!!!
Btw,.. in which demos can I find these?
- the fullscreen sine scroller (sanity is dead, woc)
- the arte rotzoom
these two are also must see-demos:
odd stuff by sector one & dune
http://www.pouet.net/prod.php?which=1960
virtual escape by equinox
http://www.pouet.net/prod.php?which=109
be also sure to check out equinox' website: http://equinox.planet-d.net for some java conversions of good old atari effects :)
odd stuff by sector one & dune
http://www.pouet.net/prod.php?which=1960
virtual escape by equinox
http://www.pouet.net/prod.php?which=109
be also sure to check out equinox' website: http://equinox.planet-d.net for some java conversions of good old atari effects :)
Yeah, Odd stuff is a great thing! That sidlike music is lovely, I tried to record it with SainT as a YM but it isn't sounding very well, WAV did a bit better, but still bad imho..
Virtual escape was the first AtariSt demo I had ever seen, preety much liked it..
Optimus
P.S. I would ask onemore, in which AtariSt demos can I find the other 2 Chaos parts (sine scroll, arte rotozoomer)
what about TCB?
optimus : according to moondog and modmate on dhs.nu bulletin board,
Quote:
there is a 4plane bitmap rotating zoomer by chaos in the ´93 megademo "a grumbler in the rutting season" by electricity, another screen, a starwars scroller appeared in the ´92 acf demo "just buggin"... about the third i´m not sure
Quote:
the third screen moondog was talking about is the chaos screen in "the year after" demo by the german alliance. it's a zooming and rotating scroller with a moving background texture...
>megademo "a grumbler in the rutting season" by >electricity
Damn, I can't find this, neither in the Pacidemo website (http://pacidemo.planet-d.net/html.html) nor by searching in google. If anyone has it, I would appreciate if he could sent that to me at optimus6128@yahoo.gr (And not at hotmail cause I don't have too much free space there)
As for the second one (the year after) it can't run in SainT and in Pacifist, Kaos part is not beeing displayed properly. I will see it later when I will get my new Atari working..
Damn, I can't find this, neither in the Pacidemo website (http://pacidemo.planet-d.net/html.html) nor by searching in google. If anyone has it, I would appreciate if he could sent that to me at optimus6128@yahoo.gr (And not at hotmail cause I don't have too much free space there)
As for the second one (the year after) it can't run in SainT and in Pacifist, Kaos part is not beeing displayed properly. I will see it later when I will get my new Atari working..
The ST description is pretty accurate, but no one talk about the STE that arrived years after. The STE features:
- Complete video adress (the 8 missing bits are here) that can be changed every line (give us easy multidirectional scroller, and splitted screens..
- A shift register that allows you to move the begining of the nex line at pixel level (thus having smooth horizontal scrolling.
- A "line width" register to create virtual frame buffers largers than the displayed area.
- Instead of 512 colors, we now have 4096. Just that the encoding is a little bit weird, since the new "very least significant bit" is the last one. So a component is coded as bits 0321 :)
The STE also has "a blitter", that was only present in the "Mega" version of the ST. It's far from beiing as complete than amiga's blitter. Than one only know how to transfert blocs of data with one source, and one destination, performing optionaly a binary operation (xor, and, or ...)... note that the blitter share it's clock cycles with the processor, and since there is no fast ram on an atari, if you perform something with the blitter the cpu is stalled...
For the sound, we have two major modifications:
- A small audio device (MicroWire interface) that allows the STE to put more/less treble in the sound.
- A DMA chanel that can replay one 8 bit mono or stereo sample at a fixed frequency choosed among 12.5, 25, or 50khz.
I believe that's all.
You can check what I was doing on the Atari before going back to the Oric on pouet. Just look for group "Next".
- Complete video adress (the 8 missing bits are here) that can be changed every line (give us easy multidirectional scroller, and splitted screens..
- A shift register that allows you to move the begining of the nex line at pixel level (thus having smooth horizontal scrolling.
- A "line width" register to create virtual frame buffers largers than the displayed area.
- Instead of 512 colors, we now have 4096. Just that the encoding is a little bit weird, since the new "very least significant bit" is the last one. So a component is coded as bits 0321 :)
The STE also has "a blitter", that was only present in the "Mega" version of the ST. It's far from beiing as complete than amiga's blitter. Than one only know how to transfert blocs of data with one source, and one destination, performing optionaly a binary operation (xor, and, or ...)... note that the blitter share it's clock cycles with the processor, and since there is no fast ram on an atari, if you perform something with the blitter the cpu is stalled...
For the sound, we have two major modifications:
- A small audio device (MicroWire interface) that allows the STE to put more/less treble in the sound.
- A DMA chanel that can replay one 8 bit mono or stereo sample at a fixed frequency choosed among 12.5, 25, or 50khz.
I believe that's all.
You can check what I was doing on the Atari before going back to the Oric on pouet. Just look for group "Next".
the mp3 of the Odd Stuff-soundtrack is available for download at www.scenemusic.net.
Use Steem to view the demo rather than saint :)
Use Steem to view the demo rather than saint :)