Posted By
Litwr
on 2006-09-12
09:22:18
|  +4 biggest screen resolution
I've found that Summer Events use 192x252 screen. SVS 31 lines demo is 320x247. Standard screen is 320x200. I think it's possible to use up to 320x296 resolution. Gaia wrote that is possibility to use 400x400!!! I have serious doubts about this... What is the biggest +4 screen resolution?
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Posted By
Bionic
on 2006-09-12
11:47:30
| Re: +4 biggest screen resolution
About 400x512, but severe limitations apply 
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Posted By
Bionic
on 2006-09-12
11:57:30
| Re: +4 biggest screen resolution
May be as good as any reason to give this away. This is a screenshot from a part I started to code for last years coop demo:
http://www.digital-circuits.org/images/IMG_6430.JPG
Happy pixel counting! The vertical screen splitting is due to technical reasons (it is a true monochrome/multicolor split in hires mode!). The vertical limitation is simply to have more CPU time.
Unfortunately I never got much further than this screenshot, and it does not seem I will be able to finish it in the near future. The fact that it does not work with YAPE is a problem, too
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Posted By
Luca
on 2006-09-12
13:37:00
 | Re: +4 biggest screen resolution
Happy to see ya again Tim. I'm very sad because of your being busy 
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Posted By
Crown
on 2006-09-13
06:44:57
| Re: +4 biggest screen resolution
So apparently both Bubis and Bionic implemented my very old idea of switcing to NTSC mid line which speeds up the dot clock and makes the pixels smaller horizontally, increasing the potentially achieavable horizontal resolution.
Vertically you have 312 lines default, you have to keep a couple of lines for the vsync lines but every other line can be used for display. Check out Godzilla it uses exactly such a mode.
But you can increase the vertical frame size from 312 line to whatever you want, but this depends on the flexibility of the monitor or TV set you are watching it on. Some sets let you add an extra 10 lines, then they start rolling, while a 1084S monitor can easily handle around an extra 50-100 lines (don't remember the exact number, it was a long time ago, when I experimented with this.)
You might also try to reduce the number of vsync lines, but that again will depend on how well your set can handle not completely standard video signals.
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Posted By
Chicken
on 2006-09-13
07:02:28
 | Re: +4 biggest screen resolution
I was going to say "So you switched to NTSC?" because I remembered the discussion on the mailing list back then. Also I remembered that TLC suggested this on the mailing list. However, Crown and I were discussing opening side borders and similar things in some mails before. So I'm quite sure he had that idea long time ago
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Posted By
Litwr
on 2006-09-13
07:39:07
| Re: +4 biggest screen resolution
This is theoretical discussion... What is practical max +4 screen resolution? 
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Posted By
Chicken
on 2006-09-13
07:47:33
| Re: +4 biggest screen resolution
Privet!
No, it's not just theory Check out BUBIS' demo...
Also, CROWN managed to code a 42 char mode (there's a demo) and if I recall correctly he could do 43 chars (though with limitations), too.
Vertical resolution obviously seems to be limited by the display. I remember that some tv sets had problems back then with demos/games that extended the screen vertically (e.g. "rolling").
In the worst case, newer tv sets (digital components) reject "modified" signals completely and all you get is a black screen.
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Posted By
TLC
on 2006-09-13
09:41:01
| Re: +4 biggest screen resolution
You might want to ask Gaia if he still has a screenshot I mailed him 2004 summer... unfortunately, my instance got lost with the content I used to carry on a notebook. AFAIK Bubis succeeded to produce a test-version of a similar effect some few weeks later that summer.
As to whether it was "my" idea to trick the TED this way or it was someone else who "invented" it in theory, I don't know... I used to remember I had the idea back in '92, somehow similarly to the "real" interlace effect. OTOH, Crown used to code pretty wild TED effects earlier... way back in '90 or so. I guess whoever experimented with the TED or was a little bit deeper in the TED than most people might have known that switching to NTSC mode speeds things up. Those people must also have known the relation between cpu clocks and the screen (the division between the CPU clock and the screen dot clock is fixed... the dot clock is always 8 times the CPU single clock). If someone went along, he could deduce the theory of this high resolution effect thing. As to whether this was Crown or me or anyone else, well, I wouldn't make a bet. Someone might come in and claim he had the idea, say, way back in '86... ...Dunno.
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Posted By
Gaia
on 2006-09-13
09:55:39
| Re: +4 biggest screen resolution
Litwr: when I said 400x400 I refered to the normal window area with NTSC-hack and true-interlace. You must separate two things first: you can increase the visible "window area" resolution and you can increase the "overall" resolution. In the former, you extend the visible area to areas that are normally covered by the border. In the latter, you simply squeeze more pixels into one fixed size visible area, let that be border or window area.
With a similar trick like the upper and lower borders, you can completely remove sideborders as well. Depending on the display one could possibly show 480x~584 pixels by doing completely open borders, NTSC-hack and true-interlace all at the same time.
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Posted By
Chicken
on 2006-09-13
10:26:39
| Re: +4 biggest screen resolution
True interlace? This was discussed on the mailing list back then, too. Did anyone succeed? I just remember that TLC's demo looked different (fields swapped maybe?) on some monitors. If I'm mistaken on this one I apologize!
So... is there a demo with true interlace? Does it work in YAPE?
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Posted By
Bionic
on 2006-09-13
13:31:13
| Re: +4 biggest screen resolution
Well, I don't know who had this idea first, but my code does work (at least up to that screenshort ), which is a difference.
You should not forget to count the number of rows. The chars comprise 320x256 pixels, with a 80x256 multicolor area right to it. All in hires mode btw..
Real interlace does work, but it brings a lot of problems. I actually coded this with an oscilloscope connected to the video output. Getting it to work with color is another story.
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Posted By
Bionic
on 2006-09-13
13:38:43
| Re: +4 biggest screen resolution
I can confirm the 400x400 pixels from actually working code. As mentioned several times, the above screenshort only uses a part of the 400x400 area. (400x256 to be exact)
There are limitations: You can update the color attributes only once per screen (not every 8 lines) and the rightmost 80 pixels always get the color attribute #$00. So, unless you use multicolor you only can black foreground and background.
I tried a lot of things, it does not seem to be possible to restart the line register within the screen area to get different attributes. I also had some half backed version with two half-width screens next to each other (border area in center and at edges), but that was a bit useless.
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Posted By
Bionic
on 2006-09-13
13:55:54
| Re: +4 biggest screen resolution
I found another screenshort, showing interlace in action:
http://www.digital-circuits.org/images/IMG_6428.JPG
As you can see, the white and grey lines in the background have a higher vertical resolution that the chars. As bonus you can see the routine that generated this on the screenshort
The timings are actually very critical. According to my scope this code generates something very similar to pal sync pulses and it works on my display. However, things may be different elsewhere. Even on amiga it was always very painful to get interlace to work properly.
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Posted By
Chicken
on 2006-09-13
15:32:20
| Re: +4 biggest screen resolution
True interlace:
I experiemented with that a long time ago. On my monochrome monitor it looked real interlaced but my code was just experimental. I guessed, though, that colors would complicate things. But when everything is "amber" who cares about colors?
Bionic... Yes, I understood that the lines are limited for coding reason. That was clear in the first place and we all know that you can code more!
I just saw that you posted another one In the first screenshot...
http://www.digital-circuits.org/images/IMG_6430.JPG
... is that true interlace? Or just "normal" lines? I wonder because there's so much "border space" and you said you used 256 lines for hires display.
The new screen shot is cool I wish I had a plus/4 set up here. My monochrome monitor was very gentle when it came to weird signals, so I'd like to try that. Screen copy gets a new meaning
I couldn't find the demo with the Eaglesoft picture... which demo was that again?
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Posted By
Csabo
on 2006-09-13
18:39:39
| Re: +4 biggest screen resolution
I think that demo with the eagle is Chaos. See this entry in our knowledge base, the Plus/4 Encyclopedia: Sideborder.
I'll add my 2 cents to the above, but keep in mind that I could be completely wrong. Now, after that delightful disclaimer: in regards to displaying graphic information (rather than just the background color), it's possible to do that on the entire picture. While I played around with extending the sideborder, I noticed that the "border" is sometimes taken from the character on $2FF8 (or $3FF8?). So, if I put an 4x8 (since it's multicolor) piece of graphic there, it will be displayed everywhere, where normally the border would appear. Sure, it's the same character all over, so it's kind of useless, except to use it once to show it off, but possible. So it's 384 x whatever-number-of-lines we have, for area. The entire picture basically. For increasing the resultion, the above covers it pretty well (gotta admit my jaw dropped).
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Posted By
Bionic
on 2006-09-14
05:02:06
| Re: +4 biggest screen resolution
chicken: The IMG_6428... screenshot uses both real interlacing and the NTSC trick at once.
Csabo: There is also a way to use the CPU to generate bitmap data by forcing graphic fetch from a ROM bank that does not exist and disabling the line buffer. In that case the bitmap data is the last byte that remained on the bus, in fast clock mode every second processer cycle. If the CPU executes a chain of LDA #$Xx, it can be used to feed bitmap data to the TED.
Unfortunately you end up with some garbage because eventually you have to execute other instructions.
I have a program somewhere that uses this trick to display a bitmap in the border..
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Posted By
Chicken
on 2006-09-14
07:04:47
| Re: +4 biggest screen resolution
Bionic:
You meant IMG_6430... or?
Csabo:
Thanks I remembered that I read it somewhere. Actually, I've even been to the encyclopedia. Silly me
About open sideborders...
Some years ago, I tried this by applying the "C64 method" ($ff07). I discussed my "results" with Crown and he told me that he did the same way back in the late 80s. And he gave me a clever explanation what's "shown" there/where the color comes from. Maybe that can be added to the Encyclopedia as well, even though opening the borders that way doesn't make much sense.
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Posted By
Chicken
on 2006-09-14
07:16:07
| Re: +4 biggest screen resolution
Hm... I just went back to the Encyclopedia and read that Larry's and Crown's routines use $ff07. I thought Crown used $ff1e writes. So it uses $ff07 to open the borderl, too? I haven't looked into this so just forget about my last posting
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Posted By
TLC
on 2006-09-14
09:36:51
| Re: +4 biggest screen resolution
In fact that trick with feeding the TED with bitmap data by executing a series of CPU instructions works even without switching to an unused ROM bank; if you remove the upper and lower border by $FF06 magic, you end up with bitmap fetch with no TED bitmap address generation and address bus assertion, provided you keep the CPU in double clock mode; so whatever the TED reads from the data bus will be displayed as bitmap. It's kind of similar to the case when the TED reads from unconnected address space.
But AFAIK this is not new, either; I know of published examples of this phenomenon from Andreas Boose and Marko Mäkelä. Marko even wrote a testprogram that ran completely in unconnected address space (though, this is of kind of the opposite league).
As for the "difference"-thing that you mention above: I kind of agree (so much that I sort of wrote my previous reply in exactly the same sense, even if this sense might not have really come through). Speaking about theory is theoretical, something proving that something works is factual. Who cares if "I" invented this in theory? ...For me, it might be nice, but really who cares?
It may look like that we could stop here (as we seem to have reached "the" conclusion), but there is something more to this... at least as I feel.
From time to time, rumours raise up about things that have never been done before, effects that have been done for the first time ever on Plus/4, exotic TED effects and things like that, created by a couple of nice guys. Sometimes there are rumours about new, upcoming demos from the above sort of nice guys. ...O.K., but what's the problem (if there's one at all), you could ask?
Well, the problem is, all those rumours so far have all proven to be vaporware, that's the problem.
Why?
When someone tells me he succeeded to create something that, say, I had in mind or I also managed to get to work before, I feel disappointed. I'm an egoistic kind of person, after all. Philosophy says, one's ego feels threatened when something that gives him identity is threatened in its existence. Before you'd consider this, say, inappropriate, I'd ask you to tell me the feelings you got when you read this thread here; or I might as well ask Bubis to consider his feelings when he learnt I was forth to him by just three or four weeks. This is real. So?...
In the sight of this, what happens is absolutely false. Coming up with exotic things is nice, but presenting them as just rumours is really bad. ...Sometimes, back then, people knew, or, say, respected themself or others or the things they've created (I don't know which one, if not more than one is appropriate... ). I could never hear or read SCF or Mucsi or anyone amongst those guys rumouring about how cool effects they've created. You could, say, run Sign o' Times instead and wonder what you're watching. ...I wouldn't even consider this a phenomenon of today's better communication possibilities (there are other well known names who don't ever appear to rumour about things, they just come up with demos occassionally). ...The difference it makes is the feeling you get. Being a coder, you possibly feel bad when you hear someone coming up with something that you had in mind (or in test), I mean just the pure fact of deed. You possibly even stop experimenting. Or whatever. What's the use of a revolutionary effect that's also in someone else's hands, after all, even if none of you got it published? At the end, both of you may end up never publishing the stuff ('cos it's really not worth it, one feels).
When you're handed a demo, with no talks or whatever prior knowledge, the situation is absolutely different. For one, I don't feel jealous about a nice demo I see, even if it contains things I might have in mind before, or in test, or whatever. A nice demo is a nice demo. Period. You don't feel bad seeing a nice demo; you (if you like beauty) do like it, just for itself. (For one, I had absolutey no bad feelings about watching BSZ's trackmo, even if it had lots of ideas I had in mind, and some I had in test. I was truly happy about it, and didn't consider what I lost "in theory"; I simply didn't feel like that. Which is a difference).
As a conclusion, it might be useless to know, who had something in mind for the first time... as well as it might be slightly useless, or counter-productive, after all, to have a proof about something, as long as it's not respected to be featured in a demo, or a product, or whatever.
I'd be happy to see demos from guys I've talked about above (as to whom I'm talking about, I leave to their consideration), but no rumours. No vaporware. Please.
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Posted By
Bionic
on 2006-09-14
10:18:14
| Re: +4 biggest screen resolution
I am honestly suprised and a bit disappointed. What could have been a nice discussion about coding tricks instantly turned into a useless pissing contest. Grow up.
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Posted By
Degauss
on 2006-09-14
10:41:57
| Re: +4 biggest screen resolution
I remember playing around with Bionics code-snippet. I have to admit that i don't really understand how that real-interlace thing works but i had the feeling it depends heavily on the CRT-Display you are using. On my 1084S which seems to be a bit broken i gained better results (in that case: hires-lines) when i modfied the $FF1E values.
BTW: can anyone explain the real-interlace?
As for the "who's done it first"-discussion: I never saw an effect which couldn't have been improved at least a bit (at least in presentation). So why bother?
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Posted By
TLC
on 2006-09-14
14:43:53
| Re: +4 biggest screen resolution
Bionic: I don't feel like in need of defending myself (what I wrote was not aimed at you primarily in the first place; it was rather triggered by something that I read in your post. For not making this clear, I'm sorry; for what I really meant with that post, I'm not.)
degauss: true interlace is a mode all TVs normally operate in. TVs, actually, show a screen of 625 rows at a rate of 25Hz. They don't simply draw 625 rows one after the other, the refresh is done in two turns, which helps to avoid flashing. To simplify things, two frames of "312.5" rows are drawn, one after the other, each shifted by one screen row from each other in the vertical direction.
The Plus/4 generates 312 rows at 50Hz; to be able to show this on a TV-display, the TED would keep on showing a frame of always the same polarity. (This is a kind of "semi-standard" way of generating the screen; Commodore and the other manufacturers at the time would all do this ). What you can see on the Plus/4's screen is effectively half the vertical resolution a TV can do. Instead, you have twice the framerate you have in the TVs regular operation mode, which results in a more useable screen for the computer, since the screen doesn't flash at the sharp edges of the screen content like it would do in interlace mode.
Whilst most other computers are stuck in 312 rows at 50Hz (or 212 rows at 60Hz for ntsc) mode, on the Plus/4 it might be possible to overcome this by some kind of ff1e magic (as frame polarity is determined by the vertical retrace part of the screen.)
As Bionic said before, it's unclear as of now whether it's possible to do real, full-featured interlace mode on the Plus/4 (problems arise around the PAL color encoding), but he managed to do it in monochrome, even together with the horizontal resolution increasement trick.
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Posted By
Luca
on 2006-09-14
16:47:48
| Re: +4 biggest screen resolution
This is one of the most interesting discussions I read here in years, thanks pals!
Strange, Bubis is still idling, because he has important pictures too to show:
http://www.flickr.com/photos/dotsch/tags/ntsc50/
Incredible to say, I also appreciated the proud spirit of a scener like TLC, he talked in a sincere genuine manner, bring into question his own essence, and I like it. Omg pals, dangerously we're becoming an act...an acti...an...jeez got no power in my sould to say it...an _active scene_?
Indeed, vapourware must be beated, I'm with him.
From the other hand, must confess: I can give witness that one year ago Bionic did the (im)possible in order to join Crackers'Demo 4 with a revolutionary part based on his tough experience about that video format. He had to do most demanding and time consumpting stuff in those days, including to manage his loooong stay in the States.
Though this, he tried to achieve in the best way a technical result which we're still debating right now, due to the real difficulties we're spotting in several points of discussion. I still have the .d64 he sent to me in order to try the effect on several monitors, and probably he still has the 72x128 gfx in 3 colors I did for him (in 10 minutes, do you remember Tim? ). Yeah, once CD4 had been released, we didn't talked about all the lost/wasted work that took us nowhere.
You can bet on this, he tried and tried while managing his departure, an hour in the agency, the following hour on a real Plus/4. He did his best in order to achieve a decent result before the deadline. He really did his best, and I'm not able to imagine Tim as Vapourware Club Goldcard owner, absolutely not
All this, in order to say: plz guys don't loose this chance to chitchat altogether because of silly misunderstanding.
Bionic, what has just happened to your glorious nickname? 
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Posted By
Lavina
on 2006-09-15
03:04:45
 | Re: +4 biggest screen resolution
guys, I just coded a mega hype effect, it makes the TV that is connected to real plus4 to grow an arm, it plugs itself off the wall, dances around the table, than plugs back and the arm goes back to the TV and it operates further normally.
We are currently working on some minor bugfixes on YAPE to make it compatible with my new effect.
Coming soon.
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Posted By
JamesD
on 2006-09-15
12:48:13
| Re: +4 biggest screen resolution
Yeah but I bet it doesn't work on NTSC either. :D
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Posted By
Degauss
on 2006-09-16
01:10:34
| Re: +4 biggest screen resolution
Make Demo, Not War...
(Do we need to announce a "400 x something Cooperation-Demo" to stop this beef?)
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Posted By
Luca
on 2006-09-16
02:34:43
| Re: +4 biggest screen resolution
Cooperation demo? It will become a compo soon, at this point!
...an could be a further good idea too
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Posted By
Lavina
on 2006-09-16
06:07:38
| Re: +4 biggest screen resolution
At least I demonstrated one good use of a vapourware: stopping this dispute.
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Posted By
bubis
on 2006-09-17
04:53:00
| Re: +4 biggest screen resolution
Proof: http://www.flickr.com/photos/dotsch/tags/ntsc50/
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Posted By
Litwr
on 2006-09-21
01:27:31
| Re: +4 biggest screen resolution
I set 336x288 resolution for new version of "forever?" emulator. So I asked question "Is it enough for all EXISTING C+4 programs?" This discussion shows that true interlace is an odd myth... The ONE NTSC tricky demo by bubis is beyond my imagination but where is PRG? Is this extremly tricky demo compatible with any C+4 hardware?!
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Posted By
TLC
on 2006-09-21
03:55:16
| Re: +4 biggest screen resolution
These are my 2 cents (finally, thanks to Gaia who searched up his archives).
http://coroners.no-ip.hu/416x200.jpg
This is 416x200, or 52 chars. When it was created (26.07.'04), it was shown to Gaia, with whom we changed e-mails very frequently at the time (due to lots of tests done in order to improve Yape's TED emulation), and Coyote.
I severely doubt that I'll ever get around to present a trackmo that this kind of stuff would really deserve (as I guess)... so you better hurry up yourself experimenting and coding, etc. (I ain't gonna steal this pleasure from you, that is).
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Posted By
Chicken
on 2006-09-21
04:03:10
| Re: +4 biggest screen resolution
Of course I'd rather be hit by surprise when loading a TLC demo
Nevertheless, I think that these are 52 cents at least
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Posted By
Luca
on 2006-09-21
05:22:48
| Re: +4 biggest screen resolution
Levente, you're so enigmatic today: are you coding a Coroners trackmo in these days?
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Posted By
TLC
on 2006-09-21
07:07:34
| Re: +4 biggest screen resolution
Chicken: me too, you can bet... :D
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Posted By
TLC
on 2006-09-21
07:08:28
| Re: +4 biggest screen resolution
Luca: your guess?...
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Posted By
Luca
on 2006-09-21
07:10:26
| Re: +4 biggest screen resolution
TLC:mmmmm I bet on "NO" :D
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Posted By
Litwr
on 2006-09-22
04:15:27
| Re: +4 biggest screen resolution
Is there any PRG available with shown effects (416/408x200)?!!! Excuse me, but without PRG JPG picture may be produced by any graphics tools (copy & paste). Can we get any REAL proof? Any way thank you very much for the pictures!
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Posted By
Lavina
on 2006-09-22
05:33:43
| Re: +4 biggest screen resolution
Litwr, I hope this was only a joke.
You cannot really think someone would use Photoshop to produce a fake screenshot just to boost??? This is not politics here, this is the Plus4 family!
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Posted By
Chicken
on 2006-09-22
07:14:38
| Re: +4 biggest screen resolution
I guess Litwr just wanted to encourage the coders to code some demo. It's always nicer to see it on your own machine
We waited for this so many years so I think a few more months won't hurt. How about Compy X-Mas 2006? That would be a nice present for all of us Bionic, Bubis, TLC, whoever... start coding :D
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Posted By
Bionic
on 2006-09-22
14:10:14
| Re: +4 biggest screen resolution
If you want to see true interlacing: Load the second screenshort I posted (...6428), type in the hex dump that is shown there and start with G5000.
But be warned, it may not work properly on all monitors.
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Posted By
siz
on 2006-09-22
15:34:48
| Re: +4 biggest screen resolution
Just a silly question: am I right that these non-standard screen resolutions probably won't work with an S-Video to VGA converter on a TFT display?
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Posted By
TLC
on 2006-09-25
09:25:48
| Re: +4 biggest screen resolution
Siz: there won't be any problems with the higher screen resolution (other computers, like the Amiga are capable of 640x400 in normal and about 700x550 in overscan... no problems with that, except that they look like slightly blurry on composite displays). Yet, there might be problems, due to bad timings or other (similar) flaws (that might be hard, however possible to fix). This is especially true for the vertical "high resolution" trick (true interlace) that nobody yet proved if it was possible to do in a tv-standard conforming way.
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Posted By
Bionic
on 2006-09-29
06:35:24
| Re: +4 biggest screen resolution
Levente: Thank you for being so utterly constructive...
Has anybody tried the interlace routine from my screenshot? Would be interesting to compare different monitors.
Siz: 400 horizontal pixels should be pal compatible and work with the converterter. However 416 pixels are likely to screw up the horizontal timing somewhat, which may not be tolerated by all monitors.
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Posted By
Luca
on 2006-09-29
07:21:43
| Re: +4 biggest screen resolution
Bionic: you just know my results on the Commodore 1701 monitor.
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Posted By
TLC
on 2006-09-29
14:01:22
| Re: +4 biggest screen resolution
Bionic: If you mean that I wrote the above comment in the meaning of some kind of dishonour, then you might have missed the point. ...Remember, neither I could prove if true interlace (conforming to the tv-standard) was possible... so what gives? ...Yet, if you're angry about something related to me, you better tell me in a private or in e-mail... thank you.
Regarding your comment about the 416 pixels effect: false. 40*1.25=50. 48*1.25-8=52. Yours and mine result in exactly the same line timing (well, provided that yours is coded correctly... :-DDD ) It could possibly still stretched a bit, but I'm not that sure... At the left side, there is only one more place to steal, provided one needs PAL colors. Even if it could, it would possibly not be symmetric horizontally.
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Posted By
Litwr
on 2012-08-19
08:48:16
| Re: +4 biggest screen resolution
As I know the demo with more than 400 horizontal pixels is still not made. Maybe it is impossible practically?
BTW all picture links had became invalid. Is it possible to provide a directory to upload pictures? It is not difficult to set size limit for the pictures and maybe the small programs. It is not very difficult to write a script which will test all the links, move the small accessed pictures to this directory, write appropriate messages to the active post authors of missed pictures.
I am especially sad about loss of a unique Bionic's picture with 50 horizontal chars.
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Posted By
Bionic
on 2012-10-15
14:45:56
| Re: +4 biggest screen resolution
Hi guys,
I actually check this board ever other month or so. I re-upped the images on imgur:
http://imgur.com/a/AityF
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Posted By
Luca
on 2012-10-15
14:54:31
| Re: +4 biggest screen resolution
Uh, look here, how many columns
Did you used that 72x128 lil'pix in 3 colurs only I sent years ago?
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Posted By
bubis
on 2012-10-16
08:20:23
| Re: +4 biggest screen resolution
Nice! (http://zoom.it/8Bty)
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Posted By
Degauss
on 2012-10-16
07:32:41
| Re: +4 biggest screen resolution
Yeah, totally nice!
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Posted By
TLC
on 2012-10-16
11:59:22
| Re: +4 biggest screen resolution
http://harsfalvi.net/tmp/416x200.jpg
Note: the routine runs in NTSC during the sideborders, effectively providing two more (shrunk) screen character places (40 + 10 + 2 = 52 chars) whilst still maintaining full (just shrunk) sideborders + correct horizontal timing.
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Posted By
Bionic
on 2012-10-16
17:33:45
| Re: +4 biggest screen resolution
Omg, TLC managed to piss 2 cm further. AMAAZING!!
No, but seriously. Well done! Is any emulator emulating this yet?
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Posted By
bubis
on 2012-10-17
09:01:51
| Re: +4 biggest screen resolution
@Bionic: Probably you can easily answer that question if you run the same code in Yape or Plus4Emu.
BTW, this is your pal interlace code disassembled:
* = $5000
SEI
STA $FF3F
LDA #lo(irq0)
STA $FFFE
LDA #hi(irq0)
STA $FFFF
LDA #$02
STA $FF0A
LDA #$FA
STA $FF0B
CLI
JMP *
irq0:
PHA
LDA $FF1E
LSR A
AND #$07
STA reljump
reljump = *+1
BPL *
LDA #$A9
LDA #$A9
LDA #$A9
BIT $EA
LDA #$54
STA $FF1E
LDA #$05
STA $E8
TXA
l1: LDX #$14
l2: DEX
BNE l2
DEC $E8
BNE l1
TAX
LDA #$CA
STA $FF1E
LDA #lo(irq1)
STA $FFFE
LSR $FF09
LDA #$61
STA $FF15
PLA
RTI
irq1:
PHA
LDA #lo(irq0)
STA $FFFE
LSR $FF09
LDA #$71
STA $FF15
PLA
RTI
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Posted By
TLC
on 2012-10-17
18:04:34
| Re: +4 biggest screen resolution
@Bionic: this is actually the only routine of that kind that I ever did... consequently, I only had this screenshot to show (which clearly looks strange for the trained eye around the left and right sides of the screen area). I had the choice of emphasizing on why/how this is 416 pixels wide, or, possibly risk some slightly inadvertent comments about how definitely non-standard the line timing of such stuff has to be .
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Posted By
bubis
on 2012-11-24
09:56:54
| Re: +4 biggest screen resolution
Found a pretty good doc about the PAL standard, in case you are interested:
http://www.itelcast.com/_download/ITEL-video-course.pdf
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Posted By
Litwr
on 2013-09-17
14:13:29
| Re: +4 biggest screen resolution
I tried the bubis's code for the interlace effects with the emulators and the real hardware and got nothing but the flickering screen. No visible lines at all. I remember Amiga 500 interlaced 640x512 PAL graphics - it flickered but every line was visible. Is it possible to show visible 200-250 distinct horizontal lines with +4? It is a bit odd that even very old tv shows 625 lines at good quality but the exact computer hardware (even Amiga) can't make them without the flicker.
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Posted By
Rybags
on 2013-09-18
09:43:14
| Re: +4 biggest screen resolution
Interlace will show flickering when there's single pixel high stuff on a CRT. It's the nature of the beast.
You can overcome it to a degree by ensuring horizontal/near horizontal lines are at least 2 pixels tall. It defeats the purpose a little but you still have the doubling of reolution WRT where objects can be placed.
Many modern LCD displays will employ frame blending and display at 25 Hz in Pal - in some cases you even get interlace whether you want it or not as the device decided to display 312p images being fed to it at 50 Hz as 625p at 25 Hz.
How many lines you can see is a limitation of the display. Even many really old TVs have a Vertical Height control which allows you to control the under/overscan area.
Default setting is usually that 15-20 or more scanlines of the 625 are lost at the top and bottom.
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Posted By
Litwr
on 2013-09-18
13:01:19
| Re: +4 biggest screen resolution
Thank you! I wanted to get horizontal one pixel width lines with the distance at 1 pixel between them. Is it possible at C+4? The bubis's code has to show such lines but it doesn't. So I am seeking a way to prove the presence of 576 visible lines instead 288. p4fliconv gives such a proof but in a bit complicated and indirect way - we don't have a tool to create a picture with desired pixel locations in it. :-(
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Posted By
bubis
on 2013-09-19
13:27:19
| Re: +4 biggest screen resolution
Hey!
It's not my code!
It's just this (Bionic's) code disassebled: http://imgur.com/a/AityF
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Posted By
Rybags
on 2013-09-20
10:01:06
| Re: +4 biggest screen resolution
I also reassembled that program in the screendump a few years back.
The thing I found is that with the CRTs I tried it on you can even change the program to generate the extra sync pulse some scanlines further up the display and the interlace still works (not that you want to do that, but it was an interesting discovery).
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