Search found 97 matches

by alien
Thu Dec 24, 2015 12:23 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 172459

Re: horizontal scrolling on ST

(Ah, I just found your wiki. FWIW, there were 4 articles, not two)
by alien
Thu Dec 24, 2015 12:20 am
Forum: Coding
Topic: horizontal scrolling on ST
Replies: 576
Views: 172459

Re: horizontal scrolling on ST

Hi Troed, I enjoyed your presentation. I wish I could have come to STNICCC... You mentioned you wanted people to jump in with details, so here are the first to come to mind. I believe I mentioned wake states in my articles. I thought it was to do with a "desynchonization of the MMU, the Glue an...
by alien
Wed Dec 23, 2015 10:28 pm
Forum: 680x0
Topic: STE specific fullscreen issue
Replies: 34
Views: 16687

Re: STE specific fullscreen issue

Interesting, I noticed that weirdness when I played your demo in Hatari. I thought it was an STe thing, not ever having had one. The prefetch thing is simply that the Shifter needs to have been given 4 words early by the MMU so that should the scroll register be set to a value that results in most o...
by alien
Fri Jan 05, 2007 12:26 am
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

Stops

ijor wrote:Exactly :) The jitter is not random, it is deterministic and predictable (well, at least it is so in my ST). So the program predicts the jitter for each HBL.


Wow! That's interesting
by alien
Fri Jan 05, 2007 12:21 am
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

Of the 10 lines Here is how i tested it: - i wait for the VBL - i wait a variable number of HBLs with STOP - i switch to High res and almost 512 cycles later to Low res From memory, my test code went like this: - Figure out the number of cycles in a VBL (160256 from memory?) - sync up to the last l...
by alien
Fri Jan 05, 2007 12:06 am
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

Yesterday, with the top border tests, i found out something i did not know: you can disable the complete screen with a 60/50 switch done before the normal top border removal. Did you knew that ? I knew that. It happened to me when I was trying to find top overscan. I was very upset. I thought I had...
by alien
Fri Jan 05, 2007 12:00 am
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

May be they also can be used with a 71/50 switch to remove the top border instead of the normal 60/50. But Alien wrote in its document that this was not working on all STs. I have to test it. Yes it's quite possible it didn't work on all ST's. I'd have to go back and read my articles :-) Note thoug...
by alien
Thu Jan 04, 2007 11:32 pm
Forum: News & Announcements
Topic: New idea about a demo idea
Replies: 74
Views: 27127

screens

Screens I like: * my 4 bit scroller in PYM (ST-CNX) & the one I have in the Ventura which is kind of boring but I like the font. * Checksum's full screen rotozoomer * ULM's hidden scroller on Crickey WAS * Main menu of Crickey WAS * Ziggy's Full 3d & his 3d with MCoder * Oxygene's 3d for STN...
by alien
Tue Nov 07, 2006 3:49 pm
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

ijor wrote:The only way to get those scan lengths without altering sync, is to be fully synced. And again, if you don't mind putting a few lines (that are not displayed) in 508 cycles, then you could get some more new line lengths.


You can be fully synced with the 70Hz "higher" overscan
by alien
Tue Nov 07, 2006 3:59 am
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

Hi Alien ! You said you could have a 162 and 206 lines for the first line. How could you do that ? Did you just delay the switch back to 50Hz when removing the top border ? But then you should have some slight bitmap distorting as you where not synched, no ? Short answer: I don't remember. Long ans...
by alien
Mon Oct 30, 2006 11:55 pm
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

Hi Alien ! I don't know about that "NoCrew's 4 cycle enable/disable technique". Can you explain a bit or send me an email about it ? The trick is apparently to exploit the 68000's internal prefetching Leonard explains it here http://bbs.dhs.nu/coding/index.php?request=2049 , based on an e...
by alien
Tue Oct 24, 2006 6:26 pm
Forum: Coding
Topic: Keyboard controller
Replies: 64
Views: 38888

6301 coding

Yup, ST CNX pioneered it. FWIW, I sold a 127 byte keyboard, joystick and mouse routine to ESAT software in 1991/1992. So you can get them all working. Takes a lot of work to fit it all into 128 bytes.
by alien
Tue Oct 24, 2006 6:11 pm
Forum: Demos - General
Topic: Punish Your Machine
Replies: 10
Views: 6795

That doesn't even work on my real ST! I remember I had to go round to a friends house and use his STFM as I had just 'Upgraded' to the STE. STE is not ST. FWIW I had an STE in my hands for 2 hours & I tried to make it work with people talking all around me (not ideal). I almost got it working a...
by alien
Tue Oct 24, 2006 6:04 pm
Forum: 680x0
Topic: 68000 clock cycles table
Replies: 160
Views: 76181

Are you sure? If Alien is right the code (presented in page 10 of the Overscan Technique part II) is shown as: You are right, I made a typo. But as I explained, Alien was completely wrong about the behavior of "Y". So the whole seudo-code (and not just the values) regarding the activation...
by alien
Tue Oct 24, 2006 5:19 pm
Forum: Demos - General
Topic: Fullscreen graphics distortion
Replies: 16
Views: 10211

Re: Fullscreen graphics distortion

Did anyone noticed some fullscreen graphics distortion on some TV sets ? (for example the Shadow of the beast main menu from the Phaleon demo) ... it seems that having data in the right border causes this problem. Seems like this already happened in the "good old days"... cite from http:/...
by alien
Tue Dec 06, 2005 10:50 pm
Forum: Demos - General
Topic: New Game... thoughts :)
Replies: 17
Views: 9338

bod/STAX wrote:Sadly I don't have a 4-bit rout, which would be even better.


4 bit routines work only in overscan. IIRC it's in the next series of my articles about overscan in the Alive 12/13 timeframe.
by alien
Tue Dec 06, 2005 10:44 pm
Forum: Demos - General
Topic: What is "sync scrolling"?
Replies: 154
Views: 84753

Hi Alien, I’ll take the opportunity to ask you something about overscan coding (and it is related a bit to the prefetch issue). I managed to read your excellent articles on the subject that are still not translated from French. I learned a lot! Thanks. Thanks for the compliment. It's nice tha...
by alien
Mon Nov 14, 2005 1:38 am
Forum: Demos - General
Topic: What is "sync scrolling"?
Replies: 154
Views: 84753

As I said, it is possible that there are instructions with “weird” behavior. For example, and instruction might have two or more bus accesses that they are misaligned between themselves. Or it might have extra idle cycles both at the start and at the end. Again, I have no idea if such i...
by alien
Wed May 04, 2005 7:51 pm
Forum: Demos - General
Topic: Best fullscreen screen.
Replies: 83
Views: 85224

karlm wrote:unreleased overscan pacman!? c'mon now alien, release it or bear the wrath of untold emails from atari-forum members :)

karlm.


It's in Germany, somewhere in my parent's in law's house. I'm in the US... Don't even know if the harddrive still works.
by alien
Wed May 04, 2005 5:11 am
Forum: Demos - General
Topic: Best fullscreen screen.
Replies: 83
Views: 85224

Best Full Screen Ever

This is a hard question, and I don't think I can come up with a single demo. - Level 16 in the Union was a jaw dropper to me, and made me search for left/right Overscan & I liked the way left/right borders were used in the main menu of the Union Demo - TCB's super scroller in the Cuddly Demos wa...
by alien
Sun May 01, 2005 5:02 pm
Forum: Games - General
Topic: Turrican - Special Edition
Replies: 310
Views: 110225

Also, ST Connexion did a preview of a TFMX replay demo, and I'm sure Alien/ST-CNX floats about the forums here Yup. Marlon of ST-CNX wrote one that worked on pretty much anything. It wasn't optimized though. I've asked him whether he still has the source code. All my source code (including the opti...
by alien
Sat Apr 30, 2005 4:33 pm
Forum: Demos - General
Topic: Best fullscreen screen.
Replies: 83
Views: 85224

rainbox wall

I like the creative use of Overscan in the Rainbow Wall demo. It's not as technically to the limit as some of the other overscan screens made so far, but... it's a nice idea, and it's prettier than Zarathoustra's Overscan Othello (the other overscan game that made it out). Although as Paulo said, I'...
by alien
Sat Apr 30, 2005 2:27 am
Forum: Demos - General
Topic: Best fullscreen screen.
Replies: 83
Views: 85224

I can't get that image to work in SainT or Steem, am I doing something wrong? I have tried the obvious changing RAM and TOS config but on Steem it resets continously and on Saint it tries to boot from it then goes to the desktop and can't read from drive A. Has anyone managed to get it working with...
by alien
Sat Apr 30, 2005 2:20 am
Forum: Demos - General
Topic: What is "sync scrolling"?
Replies: 154
Views: 84753

Damn, I got the examples wrong: exg d0,d0 ; 6 cycles move.b 0(an,dn),dn ; 4n+2 instruction starting at 4n + 2 boundary: takes 14 cycles and an example of case 2 would be nop ; 4 cycles exg d0, d0 ; 4n + 2 instruction starting at 4n boundary: takes 8 cycles An example of case 3 is nop ; 4 cyc...
by alien
Sat Apr 30, 2005 2:02 am
Forum: Demos - General
Topic: What is "sync scrolling"?
Replies: 154
Views: 84753

The cycle by cycle order (including prefetch cycles) of a specific instructions is fixed in microcode. Let’s call “penalty” the additional 2 cycles inserted by GLUE for instructions that attempt a misaligned bus access. An instruction that takes 6 cycles (or any value not multiple of 4) will genera...

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