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PostPosted: Sat Feb 04, 2017 12:40 pm 
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Fisher wrote:
- And at last but not least, is the color subcarrier what carries the colorburst? I'm a bit confused about these two names...
Yeah. The colorburst is a marker at a specific time after the hsync pulse to indicate a specific angle or color. (in NTSC, that's pure hue "-U"; in PAL-B it alternates betweens -U-V and -U+V)


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PostPosted: Sat Feb 04, 2017 1:23 pm 
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Fisher wrote:
How can this ROM be dumped.

I have read that it can be dumped by interrupting the boot process at a certain point and then displaying the contents of the ROM on the TV. Unfortunately, your N64 has to boot in order to do that, and you would need a flashcart, and you would need the dumping tool to put on the flashcart.

It could probably also be dumped by using a logic analyzer to spy on the CPU reading the ROM when it first powers up, or by decapping it, but I don't think you have the equipment to do either of those.

l_oliveira wrote:
The main "transcodification" thing on the Brazilian N64 is a pin of the video encoder IC which has it's connection inverted (from + to GND or GND to + I don't remember) and the RCP-NUS clock source is replaced from 14.31818 to 14.30444.

Interesting. I wonder if that means it would be easy to modify a PAL-M N64 to PAL60 (or PAL to PAL-N, or NTSC to NTSC4.43), just by changing the oscillator.

l_oliveira wrote:
The PIF-NUS-M is important to give the video the correct timing when interlaced video is used. If you mod a NTSC unit to PAL-M and keep the NTSC PIF you will have B&W video on interlaced video due to a timing problem with the chroma burst.

That's because the boot ROM in the NTSC PIF tells the game it's running on a NTSC console, so the game sets up NTSC timings and not PAL-M timings. You can fix this with a Gameshark instead of swapping the PIF. (IIRC, it's the same code for just about every game.)


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PostPosted: Sat Feb 04, 2017 1:26 pm 
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Great!!
Solved virtually all my doubts!!
Thanks!! :beer:
Quote:
If you mod a NTSC unit to PAL-M and keep the NTSC PIF you will have B&W video on interlaced video due to a timing problem with the chroma burst. (A good example is the N64 Killer Instinct game)

I need to take a look on my working N64.
Does a list of games that trigger this effect exists?
I don't have much games, I think 10 or so...
And they're becoming quite expensive here!!
Quote:
PS1 has some special optimizations to make the CXA145 image better:

I'll also check my PS1 I'm not sure if it's PAL-M.
On PSONE I saw only a crystal exchange.
How does the alternating phase behave in these cases?
Quote:
Again, timing problems with the color burst. They put two 100nf capacitors at strategic spots to reduce that a bit.

I'll do some tests. I think the TecToy's one I have takes the signal direct from the video controller.
They should have modded the main clock on later releases.
But unfortunatelly this causes the freaking "rainbow banding", wich seems to be mostly gone with the crystal.
Quote:
Basically... PAL-M is a hack and you're better avoiding it like the plague.

Yes, I sure want to!
How hard would be to convert an old TV, if ever practical?
I think I should be asking this on an electronics forum... :oops:
Can someone recomend a good one?
Maybe when the analog signal is turned off I should do my parents a favor and convert their TV to NTSC.
Or even better, gift them with a newer LED one!!

Quote:
Yeah. The colorburst is a marker at a specific time after the hsync pulse to indicate a specific angle or color

Any recommended books that explain these (and other) terms?
This seems to be basic knowledge that I'm missing, and at least on the places I've been reding it only gives me more doubts. :cry:

Well I relly feel strange playing retrogames on a LCD TV...
They just don't seem to fit well. It can be the nostalgia that makes me see those things with "pink glases". :mrgreen:
Maybe I should be getting used to it, I think CRT TVs will become rare and difficult to mantain.
In 30 years I think most of them will have failed to work, unfortunatelly :-(
So whem (if) I ever got this old, with rheumatism on the fingers, I think old games on CRT TVs will be just histories I will tell to my grandsons...

Edit:
OOPS!!
I didn't saw Joe's post...
Quote:
I have read that it can be dumped by interrupting the boot process at a certain point and then displaying the contents of the ROM on the TV.

Can it be done with a Gameshark?
I've seem a schematic that could convert a standard Gameshark to a Gameshark pro.
But I just can't find it now :-(
Would be great if the PIF could be exchanged by a microcontroller running it's code.
So a region free N64 would be possible! :-)


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PostPosted: Sat Feb 04, 2017 1:55 pm 
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All Tec Toy megadrives use PAL-Mx15 (53.634Mhz) crystal oscillators. To make them work in NTSC that need to be replaced with a 53.693Mhz oscillator. For 50Hz PAL the correct clock is 53.203Mhz (4.433Mhz x12)

Actually, if the encoder chips were made with PAL-M in mind (they were not) it wouldn't be bad. The problem is them operating out of spec.


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PostPosted: Sat Feb 04, 2017 2:30 pm 
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I took a look at my N64.
It's transcodified.
It has a crystal of 14.30244 and the pin 7 of the ENC-NUS pulled to GND.

Would this frequency difference be a try to correct the bug?
I've been told that 007 had this bug too.
I have Goldeneye 007 and it's not present.
Maybe it's the other 007, the world is not enough...


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PostPosted: Sat Feb 04, 2017 2:42 pm 
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The NTSC x4 crystal is really easy to get. You can pull one from a dead PC motherboard. Remove it, any bodge capacitor that might be installed, install the NTSCx4 crystal and put NUS ENC pin back to the board.


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PostPosted: Sat Feb 04, 2017 4:38 pm 
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Fisher wrote:
Quote:
I have read that it can be dumped by interrupting the boot process at a certain point and then displaying the contents of the ROM on the TV.

Can it be done with a Gameshark?

Maybe. I don't have anywhere to set up my equipment, so I can't find out right now.

Fisher wrote:
I took a look at my N64.
It's transcodified.

Without the PIF(M)-NUS chip, there's no reason to dump it. If you're able to get it to work, you could try this Gameshark code to complete the conversion from NTSC to PAL-M:
(wrong code removed)
If any games have messed up color, or no color at all, this might fix them.

Edit: it might work better if I give you the right code:
Code:
F0000303 0002


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PostPosted: Mon Feb 06, 2017 12:52 pm 
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@l_oliveira: Great idea! I'll scavenge a crystal from an old motherboard as soon as I can make my Gradiente's N64 work or I can transcode my parents' TV. Else I'll have the same problem. Thanks for the info!

@Joe Thanks for the info. For now I don't have any games with this bug, nor a GameShark. Maybe the one I saw on sale cheaper because it was black and white is hiting this same bug.
Any idea if it's really possible to convert a regular GS on a GS pro or it was only my imagination?

I had no take a look at the Mega drive, but I think it already has some capacitor on the crystal.
As soon as I can I'll post some pics of the bug.
Maybe I could try the same SNES mod. Any chance it would work?
I also could get the scanned Phantom System's schematics, wich I'm sharing here, just in case someone else needs it.


Attachments:
GRADIENTE PHANTOM SYSTEM.jpg
GRADIENTE PHANTOM SYSTEM.jpg [ 1.16 MiB | Viewed 871 times ]
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PostPosted: Tue Feb 07, 2017 5:22 pm 
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Just if someone is as curious as I am, here's the Playtronic's NES transcodification board.
A far more complex circuit. I just wish to know how it's plugged on the mainboard and how it's doing it's job...

The solder side:
Attachment:
File comment: Solder side
Nes BR Transcoder - Solda.png
Nes BR Transcoder - Solda.png [ 1.78 MiB | Viewed 843 times ]

The componnent side:
Attachment:
File comment: Component side
Nes BR Transcoder - Componentes.png
Nes BR Transcoder - Componentes.png [ 1.58 MiB | Viewed 843 times ]


I know the smaller IC (BA7046) is a sync separator. The other IC (BA7045) is a NTSC to PAL format converter. I just can't understand the TTL chips on it, to sync?
Maybe they didn't made a good job, since I saw many of these NESes with altered colors :-(
I still need to do the Phantom's circuit and see how good (or bad) the image becomes...

I also would like to know how the french NES does RGB.
Probably it has an extra board to split the signals.
Would love to see this extra board!!


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PostPosted: Tue Feb 07, 2017 5:39 pm 
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The French NES has an internal PAL decoder. But I too wonder about its comb filter or lack thereof. Without one, you get Hanover bars.


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PostPosted: Tue Feb 07, 2017 6:18 pm 
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I can see why that board was taken out of the system... It cracked. Probably someone fastened the screw too tight and it snapped.


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PostPosted: Tue Feb 07, 2017 7:28 pm 
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Fisher wrote:
I also would like to know how the French NES does RGB.
The silver box that would have contained the RF modulator instead contains a Sony V7021 = CXA1621, an all-in-one NTSC-or-PAL-to-RGB demodulator.

Its datasheet recommends a 1-scanline delay line (i.e. the comb filter), which would conceal the Hanover bars. We'd need an actual picture of the component side (to match the occasional good ones we can get of the solder side) to make sure they're doing that.

As far as the daughterboard you posted pictures of... I'm tracing it now. I'll edit this post, or add a new one, as I figure out more of what's going on.

The 74'161 (and 1/6 of the 74'04) is making a divide-by-3. It'll count 13 14 15 13 14 15 &c. It's clocked by a highpassed version of some signal from P1 (pin2 - C1=10nF - 7404pin9 - 7404pin8)
Half the 74'74 takes that output to make it a divide-by-6. This should convert the 21.5MHz main clock into the desired modulation frequency

P1 pins:
1 - gnd
2 - 21.5MHz clock input
3 - stop and zero chroma phase
4 - delayed ("acknowledged") and latched copy of pin 3 (latched by falling edge of pin 2)
5 - PAL-M video out
6 - NTSC-M video in
7 - +5V

Not clear what why pins 3 and 4 are wanted here.


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PostPosted: Wed Feb 08, 2017 5:42 am 
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I've found some pictures.
Attachment:
DSC07583.jpg
DSC07583.jpg [ 170.64 KiB | Viewed 809 times ]

Attachment:
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Attachment:
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DSC07588.jpg [ 172.37 KiB | Viewed 809 times ]

Attachment:
Captura de tela de 2017-02-08 10-38-44.png
Captura de tela de 2017-02-08 10-38-44.png [ 909.79 KiB | Viewed 809 times ]

Looks like the board pins are these cable colors:
Code:
1- Brown
2- Red
3- Orange
4- Yellow
5- Green
6- Blue
7- Purple

The orange wire should be PPU /INT (or is it PPU /RST?).
I just can't figure out the yellow wire...
Is it GND??
Looks like it has a trace cut near the CIC and it's soldered on it.

@l_oliveira I'm not sure, but I think this board was from a NES that was on a flood.
If I remember correctly, the owner opened it and it was full of the river's water.
This may had damaged the board. Or, as you said was the screw.
The rest of the unit was on a miserable state... very dirty and smelling like sewer.
That was sad!! :-(


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PostPosted: Wed Feb 08, 2017 7:08 am 
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My advice is not use that board as it causes wrong colors on RED and GREEN (RED becomes purple-ish and GREEN becomes "brown-ish" due to color matrix differences between PAL and NTSC encoding). If you must use PAL-M, use a native PAL-M PPU from UMC as that will give you correct, perfect colors.

Nintendo would never buy a PPU from a pirate/clone company nor would put money at making a proper PAL-M PPU for the NES, but they did modify the SNES, N64, made the Game Cube and Wii support for PAL-M natively as manufacturing option.

Because they would not buy a clone PPU nor make a new one for Brazil they decided on making that bodge board.


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PostPosted: Wed Feb 08, 2017 8:14 am 
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Sure! I saw some of these NESes with color problems.
Some of them got fixed afer a couple of resets, others don't...
Have you seem a transcoded Phantom? How good (or bad) is it?
I agree with you. A proper PAL-M PPU would be the best solution, but I'm kind of going on the cheap side, since most of the parts I already have at hand.

I'll try to take a picture of the Hi Top Game and this Phantom screens for comparisons.
I'm not sure if the PPU's palette are different or the decoding circuit at the TV is confused and gives sort of different colors.
I would say that the colors are "stronger", but not saturated.
Well... I just don't know how to describe it properly, so, some pictures may be better.
Any game suggestions? I was thinking in write a palette test program to a flash ROM (this one from Blargg seems just fine) and take pictures, but this will take some more time. Maybe I try Ninja Gaiden, Battletoads and Super Mario Bros 3.

Any chance you know what was modified on the Wii?
I just got one with a dead drive but no loaders worked on it...
Looks like the game checks the drive at runtime.


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