Small LCD display...

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This includes generic Oric talkings and things that are totaly unrelated but want to share with people here :)
mmu_man
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Small LCD display...

Post by mmu_man » Wed Nov 26, 2008 1:58 pm

I've been trying for some time to find something I could use as a display for my ORIC...
I checked the LCD photo frames everyone will buy for xmas, but almost none have a video in (I recall finding one, but that was months ago), and aren't that cheap anyway...
OTH I just noticed the car DVD players usually come with pairs of LCD displays, and some are also shipped alone, like:
http://www.feuvert.fr/son-video-navigat ... D_ECR.html
Both the scott and irandom displays seem to have composite in, so a little trick would be needed but it should be doable, and they seem to have enough resolution.
manual for the scott one:
http://www.d-klik.eu/socrimex-web/uploa ... _im_gb.pdf

An interesting use would include battery powered "portable" ORIC, as they just need 12V input ;-)
I think it should be possible to find those cheap on ebay...

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rgb lcd screen

Post by romualdl » Sun Dec 21, 2008 5:02 pm

Hi there,

You can easily modify a basic composite playstation mini lcd-screen to plug your RGB oric on it. I've explained how to mod the bigben model here (in french sorry) :

http://www.vieuzordiland.fr/index.php?o ... &Itemid=34

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Twilighte
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Post by Twilighte » Tue Dec 23, 2008 4:27 pm

I've got such a screen (ok, not big ben but the Joytech one). Trouble is i hear from others that rgb will only work on french orics because the signal the real oric outputs is high enough to trigger the rgb lines.

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lcd screen

Post by romualdl » Tue Dec 23, 2008 9:56 pm

hi there,

I don't know about the difference in terms of level between french and non french oric. If you're talking about the "commuting" stuff, when you plug the oric the TV knows it's rgb signal because it receives some voltage on a given pinout there's no need here. In fact it's a composite only screen (for psone) but which is able to take other signals thanks to the video chip in it. Without modification you cannot add rgb or yuv signals (the bigben I have is also able to take yuv but it implies some fiddling with a pair of resistors, I was too lazy). In the mod I've performed I've modified the wiring so that when switching to RGB mode the chip is then fed internally with the necessary voltage so there's no need for a modified oric or a powered scart. If you are interested in the "logic" of the mod I can translate it to English.

All the little lcd screens like that may not be able to take rgb with some soldering, it depends on the video chip used. I don't know about the joytech never had one.

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Twilighte
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Post by Twilighte » Tue Dec 23, 2008 11:56 pm

Well i am very resistant to take the joytech monitor apart. I bought it new for around 100 pounds and it already comes with composite and rgb connectors. If it is possible to directly connect to oric then i would be willing to have a go.
Can't remember what SM or someone said about connecting composite to before UHF modulator inside oric?

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oric

Post by romualdl » Wed Dec 24, 2008 2:56 pm

Hi,

Have you tried to connect your oric to the Joytech? I've been reading the manual of your monitor and it should be ok. Use the sys button to choose between ntsc/pal and the input selection (the one next to the sys button) to cycle through RGB/composite/svideo. You don't care about the commute stuff because it was made for tv which had to be told through some voltage to choose between one type of signal or another. Here your monitor takes rgb and is selectable through some button so it should be ok. If not you should have a look at your scart cable which may not be ok.

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Symoon
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Post by Symoon » Fri Dec 26, 2008 7:03 pm

Well, I just got the Joytech screen.
I am no expert, but it only displayed my French Atmos (with the 50/60Hz problem Fabrice described: at the default Oric frequency, some lines don't appear).
The UK one gave a scrambled black and white picture (even by changing the SYS parameter). I didn't try to power the Scart.

Oh, and the Atari ST was displayed like a charm (once the "changehz.prg" program was run ;-))

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Post by Symoon » Sat Dec 27, 2008 12:24 pm

I tried the French Atmos with the UK SCART cable (so, unpowered), and got the same scrabled screen than the UK Atmos.
So it might require the SCART being powered ? I tried but it didn't work either. Very strange.
BTW the UK SCART cable I'm using works fine on my (or former Romu's :wink: ) Amiga monitor.

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Post by Twilighte » Sat Dec 27, 2008 7:08 pm

Well since Fabrice recommended the joytech to me back in May he then sent me a new Oric ROM that supports the better hz screen. How possible would it be to get hold of (or swap) a french atmos with my English one?
Anyone interested?

It may even give me incentive to come to ceo on 31st. Apparently Dave Wilkins showed some interest to come to that one too :P

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Post by carlsson » Tue Dec 30, 2008 11:56 am

Twilighte wrote:rgb will only work on french orics because the signal the real oric outputs is high enough to trigger the rgb lines.
Do you mean the voltage levels on the RGB output is higher on an UK market Oric than on a French one? SCART devices usually expect analog signals in the range of 0.7 - 1V. On the other end of the scale of course you have digital TTL signals like CGA which can go up to 5V. Previously I searched the forum and some web pages for description how to build an Oric SCART cable but never found affirmative answers. Perhaps if there exists a difference between models, it will get even more confusing.

A too high voltage can be brought down in a few different ways, perhaps the easiest although not always best recommended way is to add resistors as voltage dividers.

This discussion probably should continue in the Hardware section, where I've spotted a few threads previously discussing the matter.
Anders Carlsson

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Post by Dbug » Tue Dec 30, 2008 10:59 pm

The whole topic about how to connect an Oric to a display device (tv, monitor, projector, ...) is a nightmare.

I know that connecting any Oric to a Commodore monitor (108x) or similar, is easy.

Anything else is just nightmarish. Between the output voltage, frequency, lack of composite, single sync line, lack of scart commutation power... getting the picture on a tv is hard.

On my 3 year old 82cm Toshiba, there is no way to get any picture on the screen... tried everything... until I pressed the "teletext" button and suddenly got the oric picture incrusted in the teletext window display. Hacky, but it works.

I wonder if it would be possible to create some scart cable that works everywhere, and then sell them at production price to people who need them ?

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Post by Symoon » Wed Dec 31, 2008 12:41 am

Dbug wrote:I wonder if it would be possible to create some scart cable that works everywhere, and then sell them at production price to people who need them ?
That would be great!
But the single fact that, for instance, French Atmoses have one more pin on the Oric side will make it hard to build for every Oric (not counting the Telestrat).
I recall André Chéramy made an article in the CEO Mag, a few years ago, about how to build a scart cable for Atmos or Telestrat. I'll have to dig my collection to find in which issue it was...

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Post by Twilighte » Wed Dec 31, 2008 11:56 am

Dbug wrote:The whole topic about how to connect an Oric to a display device (tv, monitor, projector, ...) is a nightmare.
I utterly agree with you and i am not willing to make xxx mods to monitor to make it work on Oric. I also have no time to mess around with hardware mods.

Symoon, are you going to CEO meet on 31st Jan? anyone else going?

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Post by Symoon » Thu Jan 01, 2009 5:10 pm

Twilighte wrote:Symoon, are you going to CEO meet on 31st Jan? anyone else going?
Happy new year to everyone around!
Yes I should be at the meet, not sure how much spare time I'll have, but I have some tapes to give back so I'll drop in for sure.
André Chéramy and Jean should be there, as well as probably Alain (long time no see), and maybe Jede.

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Post by carlsson » Fri Jan 02, 2009 3:08 pm

So if I get this correct, the 5-pin (UK) Oric has a video output like this:

* RGB + composite sync
* Signal values close to 75 ohm, but not steady?
* VSYNC 50 Hz (as per Dbug's comments elsehwhere)
* HSYNC 7.90 kHz (?? as per Dbug's comments elsewhere)

This page says the SCART voltages should be 1Vpp 75 ohm for red, 0.7Vpp 75 ohm for blue and green. A 50 Hz VSYNC doesn't seem so odd, I believe at least many TVs will accept it. Dunno about HSYNC unless I misunderstood Dbug. Perhaps he meant the signal is 15.75 kHz but transmitted in interlace instead of progressive as many other computers and video games used to? In that case, chances are that the Oric picture should be easier to display on a modern TV than e.g. NES, since newer flat screen TVs tend to have a problem with progressive signals.

The circuit described on the Defence-Force page, once derived from a newsgroup or mailing list discussion seems to use a 5V power source to buffer the signals to TTL level, then divide them again to those 0.7 - 1Vpp. Dbug wrote that it generates a poor, dark picture which perhaps means the resistors are one too many? I'm a novice when it comes to electronics but I don't quite understand what the transistors do.

Has anyone (recently) measured the raw video output from a such Oric to know which voltages we're talking about? Perhaps there exists some other IC which can be used to amplify the signal slightly less?

Did Oric ever sell their own RGB monitors to which an Oric could be connected directly?
Anders Carlsson

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