tVIstec 20 by Orb [web]
screenshot added by ultra on 2013-11-15 18:03:01
platform :
type :
release date : november 2013
  • rulez 14
  • is ok 1
  • sucks 0
popularity : 55%
  • rulez 0.93
alltime top: #8800
added on the 2013-11-15 17:59:59 by ultra ultra

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The result after a kick assembler test session.

tVIsteC 20 ... A 256 byte twister for vc20 with sound

So far i know there is no 256 byte twister on VC20 yet... Hm even no 256 byter ? Strange...Anyway

As you can see looks very like the twistex twister i did for vectrex but the code is quite different. The video setup and drawing is a lot more complicated on VC20. Also the VC20 has a 6502 and vectrex a 6509. 6509 has 16 bit registers quite cool Cpu besides...

For those not having the real machine, you can try Vice emulator with the proper settings (no expansion memory, 5kb of ram) or else it won't run: Settings -> Vic settings

Video can be found here:
added on the 2013-11-15 18:02:24 by ultra ultra
could someone plz add orb as group ?... somehow that got lost...

pouet is damn slow here atm...
added on the 2013-11-15 18:04:32 by ultra ultra
sound is kinda unnecessary imho. looks great! (=
rulez added on the 2013-11-15 18:15:26 by sensenstahl sensenstahl
Group and video link added. Nice looking twister, good stuff as usual! :)
rulez added on the 2013-11-15 18:20:15 by StingRay StingRay
thx ;)
added on the 2013-11-15 18:21:24 by ultra ultra
Oh, quite nice. Liked the sound also.
rulez added on the 2013-11-15 18:43:35 by leGend leGend
Yup, does twist. Sounds nice too.
rulez added on the 2013-11-15 20:36:02 by Preacher Preacher
Nice :) (from video, link is 404)
Loved the nfo as well :)
rulez added on the 2013-11-15 20:47:39 by Buckethead Buckethead
Pretty good!
rulez added on the 2013-11-15 21:55:08 by p01 p01
nice twister, "music", 256b on vic... yeah, i think that deserves a thumb up. Several even. But I only have 2, and pouet only allows one (why, when I have 2?).
rulez added on the 2013-11-15 23:40:20 by psonice psonice
ULTRA is... ultra! :D
rulez added on the 2013-11-16 00:10:28 by rez rez
rulez added on the 2013-11-16 02:44:50 by iks iks
One good thing done!
rulez added on the 2013-11-16 13:17:02 by baah baah
but does anybody got the file itself? I got 404 by pressing on the Download-Button...

thanks for pointing me to the actual VIC file...
rulez added on the 2013-11-18 08:47:00 by Heaven/TQA Heaven/TQA
I have fixed the download link.
added on the 2013-11-18 09:06:14 by StingRay StingRay

hm seems to be a bug with the link... if you do not add http:// infront of the url or so...
added on the 2013-11-19 20:38:15 by ultra ultra
No, that wasn't the problem, the spelling of the file name was wrong (lower case 'c' vs upper case 'C'). :)
added on the 2013-11-19 22:23:47 by StingRay StingRay
oh... didn't see that...

but i was talking about the video link in the first comment... this one is correct and gives a wrong link looks like a link inside of pouet...
added on the 2013-11-19 22:28:48 by ultra ultra
just converting the source to Atari8... clever usage of VIC-1 hardware... (8 chars wide screen etc).

maybe after 20 years of 6502 coding... I don't get the magic trick here: ;=)

LDA sintab,x
LDY sinpostab,x
LDA sinbittab,x
STA (scrpos),y
I compared the plot routine in vice monitor and source code and it seems no typo... or is the unnecessary LDA sintab,x there for "slowing down" the code??? :D
oh...there is no magic in there... indeed that makes no sense...
seems i didn't see the useless lda sintab,x ;)

but be careful some variables @$40-$50 needs to be 0 maybe on atari8 they aren't 0 ... otherwise you will get wrong results.
on vc20 the system clears some of them and i'm using the $0 ones...
added on the 2013-11-20 10:52:27 by ultra ultra
ok. runs on A8...

only thing is the damned 128 char limit vs 256 VIC has... but next step will be to go bitmap mode anyway ;)
another question regarding your sin generator... it is a simple approxmiation and can this be adjusted? f.e. instead of 64 pixel wide half of amplitude or 40x amplitude?

(ok... I could use the sin-generator build in assembler but well... just wondering).
cool @a8... if done send me the source ;)
it can be adjusted ... tmp1 is the start value. in my case it's $100 and sbc #4

$100 sbc #4 ->64
$c0 sbc #3 -> 48
$80 sbc #2 -> 32
$40 sbc #1 -> 16

other values will not create a clean "sin"...
added on the 2013-11-20 14:02:38 by ultra ultra
i mean you always have to double or half both start value and sbc... if not the sin is not clean...
added on the 2013-11-20 14:08:37 by ultra ultra
no... ;) sorry this is more correct...

amp = n * 16
startvalue = n * $40
sbc = n

for example... if you want a 128 wide sin:
amp = n * 16
n = amp / 16
n = 128 / 16
n = 8

startvalue = 8*$40 -> $200
sbc = 8
added on the 2013-11-20 14:21:41 by ultra ultra
ok. thanks... will do... I can send you the WIP already. E-Mail-Adress?

everytime I touch VIC code I love the machine... simple but the VIC is so flexible...
ultrafex1 at gmx.de ...thx... maybe i'll do something on it again...

yeah vc20 is cool... but unforunately a bit too less memory limits you quite often... esp in music and stuff... but on the other hand that's the challenge...

@love how about doing a demo on it ? ;)
added on the 2013-11-20 15:53:00 by ultra ultra
rulez added on the 2013-11-25 00:46:48 by tonyrocks tonyrocks
rulez added on the 2013-11-25 15:51:57 by whizart whizart

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