VGA to RGB and RGB to VGA

[Zetr0]

Originally Posted by SkippyAR

Does OS3.5 have any support for VGA? Have they're been any drivers coded of recent that support VGA these days?

Under productivity modes there are a handfull of screen modes that work with a VGA monitor at 31kHz however only mode promoted WB programs would benefit from it.

Games, would not

@Zetro, yeah I've noticed. Just been messing about with them. WB looks really nice in Multiscan 640*400. But obviously when I go to use an Intuition program such as Octamed 4 then all hell breaks loose.

Besides, even with a 68030@50, using 256 colours in 640@400 is useless.

And I suppose even with external devices such as EZVGA from eyetech are going to be a load of rubbish too, because all the weight of running in these modes is still upon the processor.

So although it looks nice, its completely redundant, because its like carrying a dead horse.

[Zetr0]

An RTG Amiga, is a wonderfull Experience!

if you ever get the opportunity, one should not miss out on it!

Yeah Zee, that seems like the most sensible option really. But for an a1200 its just too much expansion and expense!

[Zetr0]

I have to agree.... but i have some theories that i hope to try out this year at the UNI lab

my hope is to be able to create a zorro2 to isa2 port that will run a 2/4mb video card .... hopefully....

this way, one could be put internally in an A1200 / CD32 / mayhap if i can get it working for a zorro port it could happen for A1000 / A500 / even a600 after modification.

Do you have to do the a520 adaptor hack in order to get an S-Video Composite connecter?

I assume if you'd taken the AV transcoder VGA route you'd still only be limited to the Amiga native 50Hz x 15.60Khz frequently anyway - right?

So Multiscan/Productivity Modes will not work. The point I'm trying to make is, although the device will up-scale/de-interlace to a solid high definition resolution the actual physical resolution of the Amiga display hasn't changed.

So you'll only end up benefiting from, for arguments sake, say SuperHires 1280*512 Interlaced. How are screenmode unique parameters handled too.

IE: Unclick default option and resize to...

1. SuperHires 640(1280)*512 (still very low work area)
2. Overscan a large physical area 1280*1024, would this be rescaled to fit the screen in VGA mode???

[Zetr0]

@Skippstah

Hmmmmm

well the 1280x512, is bigger than it sounds, or it could just be my 42" Plasma TV lol, the Screen is upscaled to 1280x1024 and is then input into VGA input on the TV. infact perhaps a little toooo big me thinks. I find 640x512 quite comfy

Alas I haven't tried any Overscan modes, although i would go out on a limb and state that these wont be re-scaled, but i will try later tonight and let you know.

[alexh]

Originally Posted by Cerberus73

i was wondering if one of these would be any good for getting a Signal from my a1200 to a SVGA screen

Why not buy a Sync Dongle and see if either work?

[pbareges]

Originally Posted by Zetr0

@pbarges

Ahhh my friend, i think i know why there is such a difference of performance...

I am using a Plasma TV no LCD... but fear not my friend, I have some SVideo boards being made as I type and i have your name down for one

with this one should go quite comftably to the SVideo in of the LCD or via the Up-Scaler

i trust you all the way...much appreciated sir!

[demolition]

Originally Posted by Zetr0

an adapter eh?
heres one hot off the MS paint

Did anyone try to build this one IRL?

I would like to make an RGB->VGA cable for the monitors which support 15kHz Hsync, like the C= adapters:

Looking at the schematic, I can see some possible errors, like the VSYNC and HSYNC labels switched around and also that the HSYNC line is connected to Amiga pin 22 where it should be pin 11. Also, pins 9, 10, 12 & 13 of the IC should be connected to Gnd.

Otherwise I think it should be possible to build this by cutting a VGA cable and putting the buffer circuit inside the SUBD shell.

[1NOM155]

Originally Posted by demolition

Did anyone try to build this one IRL?

I would like to make an RGB->VGA cable for the monitors which support 15kHz Hsync, like the C= adapters:

Looking at the schematic, I can see some possible errors, like the VSYNC and HSYNC labels switched around and also that the HSYNC line is connected to Amiga pin 22 where it should be pin 11. Also, pins 9, 10, 12 & 13 of the IC should be connected to Gnd.

Otherwise I think it should be possible to build this by cutting a VGA cable and putting the buffer circuit inside the SUBD shell.

Hi Demo, I know this is a old post, but why you should connect PIN's 9, 10, 12 and 13 of IC to GND?

regards,

1NOM155

[demolition]

Originally Posted by 1NOM155

Hi Demo, I know this is a old post, but why you should connect PIN's 9, 10, 12 and 13 of IC to GND?

Because those pins are inputs and inputs should never be left floating (unless they have internal pull-ups/downs). If they are floating, their corresponding outputs may flicker which causes higher power consumption and generates noise.
I built the circuit, only I used a 7404 instead as that was what I had. It works great with my 2001FP monitor.

[1NOM155]

Originally Posted by demolition

Because those pins are inputs and inputs should never be left floating (unless they have internal pull-ups/downs). If they are floating, their corresponding outputs may flicker which causes higher power consumption and generates noise.
I built the circuit, only I used a 7404 instead as that was what I had. It works great with my 2001FP monitor.

Hi Demolition, thanks for your help

[olav]

Sorry for my possible ignorance, but how will the IC on the previous page negate the signal?
I suppose that is the purpose of using the IC, to negate the sync signals?

For me, using just connections to each RGB, each ground, and the sync signals is enough. I guess some monitors cannot handle that, so you want to use the IC?

The reason why I ask, 1 and 1 on the inputs of an AND gate gives 1, 0 and 0 gives 0... so what is then the merit? Is there something I am missing here?!

Thanks!

[demolition]

Originally Posted by olav

Sorry for my possible ignorance, but how will the IC on the previous page negate the signal?
I suppose that is the purpose of using the IC, to negate the sync signals?

For me, using just connections to each RGB, each ground, and the sync signals is enough. I guess some monitors cannot handle that, so you want to use the IC?

The reason why I ask, 1 and 1 on the inputs of an AND gate gives 1, 0 and 0 gives 0... so what is then the merit? Is there something I am missing here?!

Thanks!

The IC is not there to negate the signals, only to act as a buffer to boost the signal. That way, you can use a longer cable before the signal will be too small. If you only use a short cable, just connecting the sync signals directly will also work.

[olav]

Originally Posted by demolition

The IC is not there to negate the signals, only to act as a buffer to boost the signal. That way, you can use a longer cable before the signal will be too small. If you only use a short cable, just connecting the sync signals directly will also work.

I see, thanks! Hence the 5V into the IC.. By long, you mean several meters?
What voltage value would you recommend for the capacitor? Can it be ceramic?
Also, would it be an advantage to connect the grounds individually to the proper grounds at the other end?

[Jope]

Originally Posted by Zetr0

@Cerberus73

an adapter eh?

heres one hot off the MS paint

Please don't use this schematic! My friend built it recently and fried his 74ls08 chip, thankfully nothing else was toasted I believe.

The text descriptions for the pins are correct in the picture, but in the schematic, the HSYNC and VSYNC wire labels are swapped, but more importantly, the wire marked as VSYNC is not connected to a sync pin, instead it is connected to the +12V supply! This will cause damage.

Seems no-one built it anyway back in 2008, as the smoke wouldn't have gone unnoticed if someone had. I can't edit the post to notify anyone, so this will have to do.

[dalek]

I have a schematic and pcb gerbers for a replica of the commodore adaptor (DB23->HD15) using an smd 74hct08. Will get it up in a public place in a week or so. Need to work on a second version that fits nicely in a backshell.

[LuMan]

@Jope - Good spot. I didn't see this thread previously, but read it with interest now it's been bumped. A decent solution to my straighforward, yet flickery, RGB-SCART connection would be nice.