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Author Topic: Testing of OSSC: Is this how it should look? (Read 852 times)

Offline John Fante

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Testing of OSSC: Is this how it should look?
« on: 2018.July.30. 18:22:38 »
I am running my EP's RGB output through a Open Source Scan Converter. A fantastic kit that gives a great picture on a modern monitor :-)

I am finetuning the settings at the moment and have come a cross an effect that I would like to know if iis intended. It is from the game Chimera that I found on EpJatek disk 2.

As you can see from the video below there is some small "noise" in letters at the bottom and some jittering in the graphics on the side. Is that normal for this game?

Link to Chimera video

Thank you in advance!

Offline geco

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Re: Testing of OSSC: Is this how it should look?
« Reply #1 on: 2018.July.30. 19:50:51 »
You have also a Nick from "bad" series, the noise and the extra characters at the bottom of the screen shows that, my EP has also this kind of Nick chip, some speccy conversions had this noise which did not have black border, and showed the extra characters also (for example in Turbo Esprit, and there was noise and jumping screen in The way of the exploding fist, now I remember only these 2 games)
I think the border effect is not fix on the side, because timing problem in the code.

Offline Zozosoft

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Re: Testing of OSSC: Is this how it should look?
« Reply #2 on: 2018.July.30. 20:43:57 »
John's machine from me, with selected Nick chip. At me on old good CRT don't see any strange effect.

I don't found this game on ep128.hu. Probably removed because buggy?

Offline John Fante

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Re: Testing of OSSC: Is this how it should look?
« Reply #3 on: 2018.July.30. 21:19:44 »
John's machine from me, with selected Nick chip. At me on old good CRT don't see any strange effect.

I don't found this game on ep128.hu. Probably removed because buggy?

It is on this disk.

It is in .hfe format since I am using it in my HxC. I have the original files on another PC atm.

I must admit I can not remember where I got the files originally. They have been on my machine for years ... :-)

Offline geco

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Re: Testing of OSSC: Is this how it should look?
« Reply #4 on: 2018.July.31. 08:43:14 »
John's machine from me, with selected Nick chip. At me on old good CRT don't see any strange effect.

I don't found this game on ep128.hu. Probably removed because buggy?
It is strange, the machine produce the same effect as mine produced back in the eighties and nineties, please try The Way of the Exploding Fist, and Turbo Esprit also, if they produce similar extra character and 'noise' in the bottom, and please try attribute pictures with IView if the machune produce strange pixels on the screen, probably these 2 things shows different Nick 'problems'?

Offline dangerman

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Re: Testing of OSSC: Is this how it should look?
« Reply #5 on: 2018.August.04. 13:25:40 »
I think the weird border is just how this game looks. I've tried loading the game into the ep128emu emulator and I still get the same unstable border.

I believe the game is a spectrum conversion and the spectrum code rewrites the border to achieve a multi-coloured effect (see attached image - it only happens on the menu because the actual game doesn't use this effect). But this doesn't work on the Enterprise because the CPU timings are different from the Spectrum.

Is it even possible to have stable border effects on the Enterprise? On the Spectrum the Z80 CPU and the graphics ULA run from the same clock, so you can time the Z80 code exactly.

On the EP, the Z80 and Nick chip run on different clocks which I guess means that you can't predict the exact timings for how long the Nick chip is going to delay the Z80. Perhaps if the variation is only a few clock cycles different and this happens during the horizontal blanking then it would work. Or maybe you would have to set up Nick interrupts and use them to do the timing?...


Offline geco

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Re: Testing of OSSC: Is this how it should look?
« Reply #6 on: 2018.August.04. 17:47:36 »
I think the weird border is just how this game looks. I've tried loading the game into the ep128emu emulator and I still get the same unstable border.

I believe the game is a spectrum conversion and the spectrum code rewrites the border to achieve a multi-coloured effect (see attached image - it only happens on the menu because the actual game doesn't use this effect). But this doesn't work on the Enterprise because the CPU timings are different from the Spectrum.

Is it even possible to have stable border effects on the Enterprise? On the Spectrum the Z80 CPU and the graphics ULA run from the same clock, so you can time the Z80 code exactly.

On the EP, the Z80 and Nick chip run on different clocks which I guess means that you can't predict the exact timings for how long the Nick chip is going to delay the Z80. Perhaps if the variation is only a few clock cycles different and this happens during the horizontal blanking then it would work. Or maybe you would have to set up Nick interrupts and use them to do the timing?...
Yes :)
yes :)
Yes, I have some stable border effect, without timing, but if you want different border effect than mine, checking Nick interrupt flag is a good idea.
You can test this just enter into the debugger of emulator:
Code: [Select]
A   1000  3E 0C        LD    A, 0C
A   1002  D3 BF        OUT   (BF), A
A   1004  F3           DI 
A   1005  3E 01        LD    A, 01
A   1007  D3 81        OUT   (81), A
A   1009  3E 08        LD    A, 08
A   100B  D3 81        OUT   (81), A
A   100D  3E 09        LD    A, 09
A   100F  D3 81        OUT   (81), A
A   1011  00           NOP
A   1012  C3 05 10     JP    1005
A   1015 


;1000 0023 0001 6F3E 06FF B1DF 6562 B253
Here is another:
Code: [Select]
A   1000  3E 0C        LD    A, 0C
A   1002  D3 BF        OUT   (BF), A
A   1004  F3           DI 
A   1005  AF           XOR   A
A   1006  01 81 20     LD    BC, 2081
A   1009  80           ADD   A, B
A   100A  ED 79        OUT   (C), A
A   100C  00           NOP
A   100D  C3 09 10     JP    1009

;1000 0023 0001 6F3E 06FF B1DF 6562 B253

or this:
Code: [Select]
A   1000  FB           EI 
A   1001  3E 0C        LD    A, 0C
A   1003  D3 BF        OUT   (BF), A
A   1005  76           HALT
A   1006  F3           DI 
A   1007  3E 01        LD    A, 01
A   1009  D3 81        OUT   (81), A
A   100B  3E 41        LD    A, 41
A   100D  D3 81        OUT   (81), A
A   100F  3E 09        LD    A, 09
A   1011  D3 81        OUT   (81), A
A   1013  3E 49        LD    A, 49
A   1015  D3 81        OUT   (81), A
A   1017  3E 59        LD    A, 59
A   1019  D3 81        OUT   (81), A
A   101B  3E 4B        LD    A, 4B
A   101D  D3 81        OUT   (81), A
A   101F  3E 5B        LD    A, 5B
A   1021  D3 81        OUT   (81), A
A   1023  3E DB        LD    A, DB
A   1025  D3 81        OUT   (81), A
A   1027  3E 40        LD    A, 40
A   1029  D3 81        OUT   (81), A
A   102B  3E 08        LD    A, 08
A   102D  D3 81        OUT   (81), A
A   102F  3E 48        LD    A, 48
A   1031  D3 81        OUT   (81), A
A   1033  C3 07 10     JP    1007
A   1036 
;1000 6020 2081 6F3E 06FF B1DF 6562 B253


Offline dangerman

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Re: Testing of OSSC: Is this how it should look?
« Reply #7 on: 2018.August.11. 11:22:54 »
Yes, I have some stable border effect, without timing

Wow - thanks for these. They look really good.

Although when I tried on the emulator, the 2nd demo wasn't stable for me - not sure if I was doing something wrong... Haven't tried it on a real Enterprise though.

Offline geco

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Re: Testing of OSSC: Is this how it should look?
« Reply #8 on: 2018.August.13. 11:23:04 »
Wow - thanks for these. They look really good.

Although when I tried on the emulator, the 2nd demo wasn't stable for me - not sure if I was doing something wrong... Haven't tried it on a real Enterprise though.
If you mean that it is not stable because the start position of colours can be changed at each start then it is normal. If the picture was moved then please try to run it on EP128 config on 4MHz.

Offline John Fante

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Re: Testing of OSSC: Is this how it should look?
« Reply #9 on: 2018.August.15. 07:13:50 »
I have been asking around a bit on the OSSC forum about the different settings on the OSSC, to be sure that I am using the best settings for the output from the EP.

There I get the info that the resistors in the cable are not big enough :?: :

"According to the video out specs the sync is TTL level and the RGB signals are 4 volts. The 100 Ohm resistors are not enough. They should be at least 330 Ohm for RGB. For TTL Csync 470 Ohm is usually used. Otherwise the sync voltage will be too high for SCART and may damage the OSSC."

Link to OSSC forum

Retrocables told me that the resistors used in the cables are as they should be according to the official EP documentation:

“The resistors value are 100ohm(in RGB signals and Sync) and 470 ohm between pin 8 and 16 for RGB activation singnal.”

I do not have any problems with a very "bright" image, but I would like to hear what people here think about the best size of the resistors in scart RGB cables? I would certainly not want to damage my OSSC ....
« Last Edit: 2018.August.15. 08:08:28 by John Fante »

Online gflorez

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Re: Testing of OSSC: Is this how it should look?
« Reply #10 on: 2018.August.15. 10:53:47 »
Practice and some expert tests have shown that the Enterprise colours and sync signals could need higher resistors on some equipments, up to 330 Ohm.
« Last Edit: 2018.August.15. 11:33:07 by gflorez »

Offline John Fante

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Re: Testing of OSSC: Is this how it should look?
« Reply #11 on: 2018.August.15. 21:08:05 »
Practice and some expert tests have shown that the Enterprise colours and sync signals could need higher resistors on some equipments, up to 330 Ohm.

Thank you :-)

I do not have the brightness problem when I use the OSSC. BUT, if I take the scart directly to my TV/monitor (an old Samsung that has both scart and DVI and VGA) then the picture is rather bright.

I will see if changing the resistors to 220R (as suggested) will make things better.

BTW: I found a modern LCD-monitor that supports 15khz output. and therefore should support the standard output of the EP.

Online gflorez

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Re: Testing of OSSC: Is this how it should look?
« Reply #12 on: 2018.August.15. 23:50:59 »
You mean multi-sync monitors. You have this list, probably not complete.

To use one of these monitors you don't need electronic adapters, only to arrange the Enterprise signals  to the VGA connector.

Personally I use my Enterprise connected to a NEC Multisync 17'' monitor with sound. It has a second DVI input that I plan to use with the GFX-NINE MSX cartridge. The two inputs are switchable with a button.  

What I don't know is if this monitor is also able to sync to 25KHz.
« Last Edit: 2018.August.16. 00:41:18 by gflorez »

Offline John Fante

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Re: Testing of OSSC: Is this how it should look?
« Reply #13 on: 2018.August.16. 07:43:41 »
You mean multi-sync monitors. You have this list, probably not complete.

To use one of these monitors you don't need electronic adapters, only to arrange the Enterprise signals  to the VGA connector.

Personally I use my Enterprise connected to a NEC Multisync 17'' monitor with sound. It has a second DVI input that I plan to use with the GFX-NINE MSX cartridge. The two inputs are switchable with a button.  

What I don't know is if this monitor is also able to sync to 25KHz.

Yes. I also found that webpage along the way :-)

How is the picture quality on your NEC?

Offline Zozosoft

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Re: Testing of OSSC: Is this how it should look?
« Reply #14 on: 2018.August.16. 08:27:57 »
Another alternative, get one Monitor-TV with native SCART input. Primary from LG then Samsung.
I'm using LG M2362DP.