VGA out for ST

[+poobah]

So, some questions for people seeking a VGA out for the ST.....

 

0) Connecting to a CRT or an LCD?

 

1) If you use an LCD monitor, are you comfortable relying on the internal scaler for non-native resolutions?

 

2) If you use an LCD, is it wide screen or 'square'

 

3) How important is the overscan area to you (on a vanilla ST, the white area around the green desktop)?

 

4) How important is 50 Hz support?

 

5) Does your CRT or LCD support any 50 Hz timings?

 

6) Do you have a 40 pin shifter (ST/Mega/Stacy) or a GST (STe) shifter?

 

7) How much soldering is too much?

 

 

Thanks!

(No, I don't have a product... yet.)

[+DarkLord]

So, some questions for people seeking a VGA out for the ST.....

 

0) Connecting to a CRT or an LCD?

 

In my case (STacy), an LCD if I can find one to replace the original screen.

 

1) If you use an LCD monitor, are you comfortable relying on the internal scaler for non-native resolutions?

 

I suppose. As long as ST-Low and ST-Med rez's come out okay, I'm good with it.

 

2) If you use an LCD, is it wide screen or 'square'

 

Tough to answer, considering I haven't actually found a replacement yet. However,

the STacy's screen seems to suggest wide-screen would fit it better.

 

3) How important is the overscan area to you (on a vanilla ST, the white area around the green desktop)?

 

Not necessary, but certainly welcome.

 

4) How important is 50 Hz support?

 

Well, given the limited amount of software, and how much is Euro in

nature, I'd like to see it.

 

5) Does your CRT or LCD support any 50 Hz timings?

 

Again, tough for me to answer, but when I do actually go to buy

one, it will certainly be on my list of features to look for.

 

6) Do you have a 40 pin shifter (ST/Mega/Stacy) or a GST (STe) shifter?

 

I've got the STacy version.

 

7) How much soldering is too much?

 

The less the better in my case.

 

Thanks!

(No, I don't have a product... yet.)

 

Well, if you can actually release a product that works across the

spectrum of ST variances, at a reasonable cost, there'll be a lot

of people (myself included) thanking you profusely.

[AtariMusicNet]

There was an idea like this being proposed over at the atari forum a few months back, but this would have been for older 40 pin shifters only.

 

I've got at least 1 of every ST type released (ST, ST+, STfm, STe etc) and would be interested in something for the mega STe that allowed switchable colour and mono out to VGA and also something similar for STe and the regular ST series.

 

Soldering is an issue for me these days but I know people who could help with that, so not really an issue and as for monitors, I'd be accessing a number of different types including CRT, square LCD and wide LCD.

 

 

Sent from my iPhone using Tapatalk

[AtariMusicNet]

@darklord, last time I spoke to Barrie at keychange, he had a Stacy in bits and the screen was still intact. Have you tried contacting him at all?

 

 

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[+DarkLord]

@darklord, last time I spoke to Barrie at keychange, he had a Stacy in bits and the screen was still intact. Have you tried contacting him at all?

 

Sent from my iPhone using Tapatalk

 

Thanks for the suggestion, but its not an original replacement screen that I want. I want to replace

the original screen with an LCD that will allow me to do ST-Low and ST-Med rez, in other words, *color*,

on my STacy.

[Shredder11]

So, some questions for people seeking a VGA out for the ST.....

 

0) Connecting to a CRT or an LCD?

 

Currently LCD TFT 19" 4:3 ratio but it is old and will not last forever...

 

1) If you use an LCD monitor, are you comfortable relying on the internal scaler for non-native resolutions?

 

As long as the image is centred properly and not in one corner, otherwise the interface needs to be able to sort this.

 

2) If you use an LCD, is it wide screen or 'square'

 

Current one square but next one will likely be wide due to scare square 4:3 ratio ones.

 

3) How important is the overscan area to you (on a vanilla ST, the white area around the green desktop)?

 

To fully enjoy demos well yes it is.

 

4) How important is 50 Hz support?

 

Many demos need this to look smooth and authentic. I would like this for sure.

 

5) Does your CRT or LCD support any 50 Hz timings?

 

I doubt it but my next one certainly will, because I will choose one based on this.

 

6) Do you have a 40 pin shifter (ST/Mega/Stacy) or a GST (STe) shifter?

 

I've got the STE version.

 

7) How much soldering is too much?

 

The less the better in my case.

 

Thanks!

(No, I don't have a product... yet.)

 

There is a demand for this and that includes myself!

[+wood_jl]

If it was widescreen, would like "bars" on the side to maintain original aspect ratio. Would be using a 4:3 initially, as long as it lasts.

 

I suppose most ST are NOT STe so probably better to cater to the larger base (ST), if not possible for both?

 

As little soldering as possible. Wish for an external box (no soldering) that would work on all machines, but I'm guessing this is not possible, and I fathom I haven't the understanding to know why.

 

I am happy to see someone working on this (GO, technically-minded man!), regardless of what comes out. This is very nice!

[Goochman]

Here is the only way I can answer your questions:

 

Id like to run my Mega 2 ST or 1040 ST (both NTSC) on any LCD monitor with Mono, Med, and Low Rez (I have a Mono cable so I could pass on that option)

 

Any stretching would make games pretty ugly IMHO - not sure what modes my LCD works with but Id hate for me to need a new LCD monitor and the connection not work.

 

I cant solder a lick and havent found anyone in the US that I could ship my ST to do the work (Classics does 8bit stuff )

 

My LCD is 'wide screen' and the Mono cable I have looks great with the ST High Rez

 

One last point - I hvae an AT-Speed and 16mhz CPU in my Mega 2 ST - so Im not sure how much room would be required to add something like this but if it has to be stock then I might be out of luck.

[+DarkLord]

 

I cant solder a lick and havent found anyone in the US that I could ship my ST to do the work (Classics does 8bit stuff )

 

 

Alex Yu at ATY Computers still does Atari ST work. Just a while ago, he socketed the CPU on my STacy

for me. He's not cheap (charged me around $60.00 for labor/parts for this), but he does good work.

 

Good point about the modifications - my STacy is going to be running at either 16mhz or 25mhz, so it has to

be able to work with that as well.

[+wood_jl]

 

I cant solder a lick and havent found anyone in the US that I could ship my ST to do the work (Classics does 8bit stuff )

 

 

Alex Yu at ATY Computers still does Atari ST work. Just a while ago, he socketed the CPU on my STacy

for me. He's not cheap (charged me around $60.00 for labor/parts for this), but he does good work.

 

Good point about the modifications - my STacy is going to be running at either 16mhz or 25mhz, so it has to

be able to work with that as well.

 

Well, there's no point in Emailing him. I've tried it a couple of times, and decided I may as well email Santa Claus. Maybe he takes old-fashioned phone calls? Recognizes your emails?

[atarian1]

 

I cant solder a lick and havent found anyone in the US that I could ship my ST to do the work (Classics does 8bit stuff )

 

 

Alex Yu at ATY Computers still does Atari ST work. Just a while ago, he socketed the CPU on my STacy

for me. He's not cheap (charged me around $60.00 for labor/parts for this), but he does good work.

 

Good point about the modifications - my STacy is going to be running at either 16mhz or 25mhz, so it has to

be able to work with that as well.

 

Well, there's no point in Emailing him. I've tried it a couple of times, and decided I may as well email Santa Claus. Maybe he takes old-fashioned phone calls? Recognizes your emails?

 

He was still around at the beginning of the year when I visited his store. He does answer the phone.

[atarian1]

So, some questions for people seeking a VGA out for the ST.....

 

0) Connecting to a CRT or an LCD?

 

1) If you use an LCD monitor, are you comfortable relying on the internal scaler for non-native resolutions?

 

2) If you use an LCD, is it wide screen or 'square'

 

3) How important is the overscan area to you (on a vanilla ST, the white area around the green desktop)?

 

4) How important is 50 Hz support?

 

5) Does your CRT or LCD support any 50 Hz timings?

 

6) Do you have a 40 pin shifter (ST/Mega/Stacy) or a GST (STe) shifter?

 

7) How much soldering is too much?

 

 

Thanks!

(No, I don't have a product... yet.)

0) LCD

1) Not really. Best to have some type of on-screen menu or something to move the image around. Even when using mono modes on several LCDs, the image ends up on top or middle of the screen with black bars on the bottom or top.

2) 'square' screens are hard to find except through mail order - usually direct from big manufacturers like NEC, Dell, etc. Best to go widescreen and have black bars on the sides to keep the correct resolution/aspect ratio

3) We need overscan for games and demos.

4) We need 50Hz support since so many games and demos come from Europe.

5) Not sure. I think so.

6) Both

7) Like others said, the less the better.

 

I hope to see this product comes true!

[+DarkLord]

Well, there's no point in Emailing him. I've tried it a couple of times, and decided I may as well email Santa Claus. Maybe he takes old-fashioned phone calls? Recognizes your emails?

 

Okay, I just don't know what to say about this. I've never had any trouble getting in contact with him

although admittedly, I can't remember whether or not I e-mailed him, or called him direct.

 

All I can suggest is to visit the website, get the store hours/phone number and call him directly.

 

I hope this helps.

 

http://www.dcn.davis.ca.us/vme/aty/

[+poobah]

Ok, interesting feedback.

 

So now lets look at reality

 

The ST video signal is a very strange beastie. I may write up a nice technical document describing it, and the implications in great detail, but for now, lets just stick with "its weird". Because it is weird there are some extra challenges for a modern display device, not all of which can be completely solved

 

When the ST is hooked to the SC1224, life is pretty easy. The SC1224 is tweaked a little for the ST, and our 60 Hz SC1224s will even do 50Hz video signals without too much complaining. Note that it is actually the monitor that allows us to do 50Hz, since all the ST does is have SHIFTER display a few extra (normally blank) lines, and have GLUE hold off on VSync for a bit.

 

Now lets imagine the ST hooked to a normal 35 KHz analog VGA monitor...

Taking a 60Hz ST video signal, and scan doubling it for output is relatively trivial, we have to sample a little quicker than normal, but it should be doable in a small CPLD. All we have to do is buffer one line of data (well 2), and clock double the HSync signal. In fact, with a bit of extra space in the CPLD, you might get 50Hz, assuming that the analog VGA monitor can sync to it.

We still have borders and probably have 50Hz... Life is good, except for the 20 year old 60# CRT taking up half your desk.

 

My assumption is that people want to connect to a modern LCD display, and therein lies the rub... The adapter above will not work satisfactorily on an LCD.

 

Using the notional adapter above on an LCD, you will likely see missing vertical pixel locations, or doubled columns (depending on the monitor chipset). You may also see some horizontal jitter from one scan line to the next. The LCD will expect 640 pixels per line, but the ST actually sends quite a bit more than that (as many as 848 depending on the specific rev of GLUE and SHIFTER). Since we only have 640 pixel locations on the screen, something has to give. Things were OK on the CRT, because there are no pixels to worry about on an analog CRT, so long as we have a sufficient phosphor dot pitch.

 

So what are the options?

 

We could stick with 640x480 which keeps timing simple, and not display the left and right borders. That gives us the correct number of pixels, so no columns are lost. We get 20 ST scan lines of border top and bottom, which isn't too bad. Making sure we get the correct 640 pixels is a bit of a challenge, and might require end-user tweaking.

 

We could go to 800x600 and write each scan line 3 times. That solves (mostly) the horizontal pixel issue, but now we won't have top or bottom borders. If a vertically squished picture was OK, we could only double the scan lines, and have large borders top and bottom. Additionally, 800x600 requires a 40 MHz pixel clock. The ST only has 16 MHz and 32 MHz clocks handy, so we'd need to generate a new 40 MHz clock. Either we synthesize it from the ST clock, or we have an on-board oscillator, but now we have to cross clock domains in our logic. Either way, we need a bigger more capable logic device (better clocks, and more logic to deal with clock domains = more $$).

 

We could also go to a wide-screen resolution, which would lets us accommodate all the ST pixels, and preserve the borders. Unfortunately, that also changes the aspect ratio, stretching the ST image horizontally. Also, a rather uncommon pixel res is required (848x480), not all wide screen LCD's will sync to it.

 

Oh yes.... what about 50 Hz... Well, some LCD's will happily sync to a 50Hz signal. In that case, we are golden. However, many will not, and those monitors won't display the image. We could buffer the entire ST screen at 50 Hz and simply display every fifth screen twice. However, that will require a lot of memory on the logic device or a large external memory chip.

 

Lastly, even if we can get a proper image sent out to the LCD, it likely will not be at the screen's native resolution, or some even division of it. Either we rely on the LCD to do a decent job scaling the image, OR, we buffer the entire screen, and insert it into a larger standard resolution that is native to the LCD (many LCDs will do this for us).

 

Now this may have sounded a little brutal, but those are the facts that we are stuck with (Short of replacing the SHIFTER and GLUE with new custom chips) Outputting the ST video signal to a modern LCD is going to require compromise, period, end of story. It's not simple or straightforward, which is why there aren't any (good) adapters you can go get today.

 

So, now, the question becomes... Which compromises are you happy with, and how much is the next 'improvement' worth to you. Bigger CPLDs and FPGAs get expensive fast, and soldering them becomes less humanly possible.

 

So, as a hypothetical, (and I mean hypothetical... there is no product, and these are NOT the prices for anything I have in mind!)

 

... Assume that we have a basic scan doubler that works reasonably well on an analog CRT at 60Hz. Suppose this device costs $100 assembled and shipped. Additionally there are options:

 

0) +$0: I'll use a CRT, maybe it will sync to 50Hz, and maybe my LCD will work and look OK.

1) +$5: supports 640x480 LCD, no right or left border, no extra 50Hz support

2) +$25: supports 800x600 LCD displays natively, option for no border, or squished vertical image with borders. 50 Hz only on panels that sync to 50 Hz signals

3) +$25: supports widescreen displays, 50 Hz only on panels that sync to 50Hz signals.

4) +$50: buffers the entire screen, does 50Hz, and can insert the image into a larger 'standard' rez, such as 1024x768.

 

Which would you choose?

If you would choose more than one, please rank your choices.

 

Thanks!

[Goochman]

Thanks for the tech writeup Poobah. Im willing to spend up to $100 for a solution - so any of the options except 1 is fine with me

 

Also - would it be possible to create a solution which plugs into the ST monitor port and then provides a VGA connector to go to the monitor thereby not needed any soldering inside the ST (of course the board would need soldering for the connectors).

[+poobah]

Thanks for the tech writeup Poobah. Im willing to spend up to $100 for a solution - so any of the options except 1 is fine with me

 

Also - would it be possible to create a solution which plugs into the ST monitor port and then provides a VGA connector to go to the monitor thereby not needed any soldering inside the ST (of course the board would need soldering for the connectors).

 

Unfortunately, I need access to signals not available on the monitor port for what I have in mind.

For what I am thinking, you remove the shifter, put it in socket on provided board, plug board into shifter socket, then make 2 additional solder connections. From there, I could either send the VGA out the ST monitor port, or to a standard DB15 that you would mount somewhere on the case.

 

I have an opinion on the best option, but I'd like to see what you all think.

[+DarkLord]

I'll second that thank you for a nice technical write-up of the difficutly

in doing this project. It explains a lot about why we've not ever seen

such a device (despite a lot of promises and false starts).

 

I reckon I'd also say that all options besides #1 would be okay, and I'm

comfortable with a $100-150.00 price range.

 

Thanks much!

[Goochman]

Id pay up to $150 for a non solder solution which doesnt seem possible - otherwise $100 + what Id need to pay for someone to solder it for me (unless it would be pretty easy and someone would write up a Soldering 101 guide )

 

This is prob the biggest issue keeping me from playing with my ST. When I got the mono cable I went nuts with Spectre and such - but color is where the fun is

[venom4728a]

Upto $150 for me, I would love to have my ST hooked up to a large LCD screen.

[pixelmischief]

I would pay $100 for such a solution, given its elegance and containment. Jens Schoenfeld's device for the Amiga 1200 is an example of what I would call "a near perfect" implementation. The only drawback is that it does not bind itself very firmly onto the chip it piggy-backs.

 

A "fair" external solution exists. Cons: The output does not look fantastic, it is an external device, and it requires a, ST to VGA cable plus gender-changer to work. Pros: it is "plug-and-play", scales internally, and costs a total of $60.

 

0) Connecting to a CRT or an LCD? - LCD.

 

1) If you use an LCD monitor, are you comfortable relying on the internal scaler for non-native resolutions? - No. Would need to scale to 640x480.

 

2) If you use an LCD, is it wide screen or 'square' - Wide screen. Willing to rely on LCD for horizontal stretch setting.

 

3) How important is the overscan area to you (on a vanilla ST, the white area around the green desktop)? - Directly proportionate to the likelihood that I will lose content in games or demos by not having it.

 

4) How important is 50 Hz support? - It is not.

 

5) Does your CRT or LCD support any 50 Hz timings? - No.

 

6) Do you have a 40 pin shifter (ST/Mega/Stacy) or a GST (STe) shifter? - STe.

 

7) How much soldering is too much? - Soldering directly to extremely small chip pins where a mistake may result in physical damage, more than 10 intermediate level soldering points.

Edited May 2, 2011 by pixelmischief

[vitaflo]

0) Connecting to a CRT or an LCD?

 

1) If you use an LCD monitor, are you comfortable relying on the internal scaler for non-native resolutions?

 

2) If you use an LCD, is it wide screen or 'square'

 

3) How important is the overscan area to you (on a vanilla ST, the white area around the green desktop)?

 

4) How important is 50 Hz support?

 

5) Does your CRT or LCD support any 50 Hz timings?

 

6) Do you have a 40 pin shifter (ST/Mega/Stacy) or a GST (STe) shifter?

 

7) How much soldering is too much?

 

0) LCD

1) Yes

2) I have both widescreen and 4:3 LCD monitors

3) Not very

4) Not important

5) No

6) STe

7) Depends. Does soldering include desoldering? I think most people would like a black box solution, but honestly, *any* solution is preferable to what we have now, which is basically nothing.

 

I'd pay whatever price is required to get a decent solution that is as easy as possible to install. $150+ is no issue at all. Also, documenting as much of this info as possible would be very helpful posterity's sake. There's so little good info out there on this that I think it's really important to write down for historical reasons.

Edited May 6, 2011 by vitaflo

[krupkaj]

0 - LCD

1 - That's hard question some LCD has nice scaler some not. Depend on the LCD

2 - If you look at ST standard resolution 320x200 which is de facto wide (16:10), I think wide monitor is OK.

3 - Lot of games and demos use the overscan, so it is important.

4 - I am from Europe area and 50Hz is a standard here.

5 - that would be a problem, there is small number of LCD with 50Hz support

6 - I Have both, ST and STE (BTW what about the autoswitch overscan for ST in high resolution?)

7 - This depend on technology. Have not problem with DIL but have not enough experience in high density surface mounting.