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AuthorTopic: CRT and VGA displays simultaneously on stock A1200?  (Read 445 times)

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Offline A1200Dude

CRT and VGA displays simultaneously on stock A1200?
« on: August 11, 2019, 05:17:32 PM »
Help please!

I currently have a mostly-stock A1200 (accelerator card, no flicker fixer) hooked up to a NEC AccuSync LCD 71V monitor via the Commodore 23-pin to 15pin adapter...great display for retro systems, displays standard 15KHz Amiga modes in addition to 31KHz and several in between. Love it, but wanted to add a CRT alongside for gaming and a more "authentic" graphics experience.

I found a guy on Facebook marketplace that sold me an Amiga 1080 CRT in good condition and it is currently in transit. What I'm looking for now is a set-it-and-forget-it way to get both displays connected to the A1200 at the same time, without having to swap cables at the 23-pin Amiga RGB port all the time. A dual-monitor, duplicate-display setup, if you will.

I found both a VGA splitter and a 15-pin VGA to 9-pin RGB cable on Amazon that at initial glance looked like they would do the job...connect the splitter to the existing 23-to-15 adapter, plug the VGA monitor into one split, and the 15-to-9 cable into the other split to then send to the 1080. But after talking it through with another user on Facebook, he pointed out that it wouldn't work because the CSYNC line from the Amiga would not pass through to the CRT from any of the splitters and cables in the chain.

I guess what I'm looking for is...are there existing solutions that I am overlooking? Or is this purely a create-your-own-custom-cables thing? If the latter, are there any users here that create cables/splitters that can help with this, or can point me in the right direction? I have zero DIY skills when it comes to cabling so any help getting both monitors connected and displaying simultaneously would be TREMENDOUSLY appreciated!
 

Offline Kronos

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Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #1 on: August 11, 2019, 06:32:24 PM »
If you plan to use the 1080 only for gaming you might want to check wether composite is good enough for you.

Back in the days I had a 2024 on RGB and a 1084S on composite as a similar setup.
1. Make an announcment.
2. Wait a while.
3. Check if it can actually be done.
4. Wait for someone else to do it.
5. Start working on it while giving out hillarious progress-reports.
6. Deny that you have ever announced it
7. Blame someone else
 

Offline A1200Dude

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #2 on: August 12, 2019, 05:12:32 AM »
Sheesh, I hadn’t even thought about using composite but that would definitely be the simplest solution.  ::) Is the quality decent enough for games compared to RGB or is there a considerable and noticeable drop off?
 

Offline paul1981

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #3 on: August 12, 2019, 11:58:44 AM »
Composite isn't really that bad at all. Try it, you might like it. When I first had my A1200, I used RF for quite a while... before I realised my tv had a Composite Video input on the back. I survived with RF so I'm sure you'll survive with Composite.  :)
 

Offline A1200Dude

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #4 on: August 12, 2019, 05:38:42 PM »
Ok, I'll just go the composite route then. Now my next question(s)...will the composite output of the 1200 automatically "turn off" when a non-15KHz mode is displayed (e.g. my Workbench screen is Productivity mode)? Or will the 1080 show a scrambled screen?

Also, is there a way to have all 15HKz modes display solely on the 1080 and all the non-15KHz modes display solely via RGB/VGA? Would really like as seamless a "dual display" setup as possible.
« Last Edit: August 12, 2019, 06:19:00 PM by A1200Dude »
 

Offline paul1981

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #5 on: August 13, 2019, 11:49:55 AM »
Ok, I'll just go the composite route then. Now my next question(s)...will the composite output of the 1200 automatically "turn off" when a non-15KHz mode is displayed (e.g. my Workbench screen is Productivity mode)? Or will the 1080 show a scrambled screen?

Also, is there a way to have all 15HKz modes display solely on the 1080 and all the non-15KHz modes display solely via RGB/VGA? Would really like as seamless a "dual display" setup as possible.

The composite output won't turn off and it will display a scrambled screen on a 15KHz monitor. What you could do is either turn the monitor off when this happens (it definitely won't do it any good keep turning it on and off), or unplug the composite output from the back of the Amiga every time, or, install a switch somewhere on the cable that turns the signal on/off. Some monitors may have a video channel selection switch so that could be pressed instead. The thing is, I wouldn't want both monitors on all of the time as it's wasting power anyway so I don't quite understand what your after. Also, those 15KHz CRT's have that whistle noise which would be very annoying if on and not being used.

The simple obvious solution is to just hook up the CRT to another Amiga so you can then pick which one you want to use. Alternatively, hook them up to the same machine and edit your Startup-sequence so that holding down the left mouse button boots into a games launcher in a 15KHz mode (TinyLauncher for example), and holding down the right mouse button boots into Workbench in a 15Khz mode (for your graphics applications). If you boot without holding any mouse buttons down then you get your normal 31KHz Workbench for your NEC LCD screen. This saves all the fiddling about, and it's what I'd do.

What you don't want to do is to accidentally display these non 15KHz modes on a 15KHz monitor because it's not supposed to be particularly good for them.  :) So, in your 15KHz Workbench boot option (RMB) you'll want to make sure you only have the PAL/NTSC/Euro36 driver in Devs/Monitors. Of course, taking this further there will be some of your software configured for the higher resolution 31KHz modes and these save their settings somewhere (usually ENVARC:) so you could have an alternative ENV with these 15KHz settings for when you boot with the RMB pressed down (I'm talking besides the obvious screenmode.prefs which would have to be switched).

Or, you could have different boot partition for 15KHz. There is a little shell program that can change the boot partition priorities, so this could be used with the mouse detection at the beginning of the Startup-sequence and cause a reboot into the 15KHz Workbench. Of course it will remember it, so you'd have in your sequence either something that reverts it back to your preferred boot (31KHz) or detect the buttons again at the beginning. For example, you might forget which mode you left it on....well, it doesn't matter really, just boot up and hold down both mouse buttons together and it'll boot into 31KHz. You can even detect a joystick press, or a key combination instead. It's all on Aminet, and your options are endless in what you can achieve.
« Last Edit: August 13, 2019, 12:13:12 PM by paul1981 »
 

Offline A1200Dude

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #6 on: August 15, 2019, 01:53:22 AM »
Ok, so the 1080 arrived and I hooked it up to the 1200 via composite. However, after some fiddling with the front controls of the monitor, I'm only able to display in B&W. Any ideas what could be wrong? (and yes, I've fiddled with the color knob)
 

Offline paul1981

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #7 on: August 15, 2019, 12:51:53 PM »
Ok, so the 1080 arrived and I hooked it up to the 1200 via composite. However, after some fiddling with the front controls of the monitor, I'm only able to display in B&W. Any ideas what could be wrong? (and yes, I've fiddled with the color knob)

Is your A1200 PAL and you are in the USA? The composite and RF from the A1200 will be PAL and the two colour systems are incompatible. If the 1080 has a RGB style input on the back then I suppose you'll have to use a VGA type monitor switch or something. Or, adding an Indivision will give you another RGB output,  but it seems overkill doesn't it.
 

Offline A1200Dude

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #8 on: August 15, 2019, 08:19:25 PM »
Yes, the 1200 is a PAL unit, but I thought the 1080 was capable of displaying both NTSC and PAL modes. If it were an NTSC television that I was connecting, I could understand that explanation, but not sure I understand why that would matter with a monitor that can otherwise show the mode.

I do have an RGB cable coming in the mail, so I'll be curious to see if that will display the color properly. But if it does, then I'm back to square one with this thread, and needing a way to switch between the monitors without having to constantly swap out the cable (and wearing down the connector on the 1200).
 

Offline SACC-guy

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #9 on: August 15, 2019, 09:00:26 PM »
IMO..
Best solution! find a monitor that responses to both 15 and 31 modes. (multi-sync)

I use a Dell SR2320lf that does this and do not plug/unplug. there are others..

The other solution You already have is a dual monitor, but better is rgb and indivision vga setup.
« Last Edit: August 15, 2019, 09:12:50 PM by SACC-guy »
 

Offline paul1981

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #10 on: August 17, 2019, 11:15:59 AM »
Yes, the 1200 is a PAL unit, but I thought the 1080 was capable of displaying both NTSC and PAL modes. If it were an NTSC television that I was connecting, I could understand that explanation, but not sure I understand why that would matter with a monitor that can otherwise show the mode.

It can display 50Hz and 60Hz, but to support both PAL and NTSC would require more circuitry so I suppose they only manufacture these monitors for one or the other to cut costs. Of course, these monitors (Amiga compatible 15KHz types) were used for video work too and it's highly unlikely a user would require both PAL and NTSC as their video equipment would either be PAL or NTSC. I might be talking rubbish for all I know but that's my educated guess.
 

Offline goldfish

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #11 on: August 17, 2019, 01:16:16 PM »
I have indivision and it seems to overide the rgb port so you get no signal out of it.
 

Offline SACC-guy

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #12 on: August 17, 2019, 07:40:33 PM »
I too have an Indivision ECS, and can see both screens, because my Dell monitor is picking up the 15 mode.

I just helped another use setup a 4000 with a RTG card and we discovered in a dual monitor system, it's software (cybergraphics)
turned off the rgb when the VGA was running
 

Offline paul1981

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #13 on: August 18, 2019, 12:06:25 PM »
I have indivision and it seems to overide the rgb port so you get no signal out of it.

Does it mention this in the manual? I wasn't aware. So the IndiAGA version cuts off the RGB port but the IndiECS doesn't?
 

Offline Motormouth

Re: CRT and VGA displays simultaneously on stock A1200?
« Reply #14 on: August 18, 2019, 11:26:27 PM »
I have indivision and it seems to overide the rgb port so you get no signal out of it.

hmmmm,
I don't have this problem.  I get both a DVI output from indivisionAGA and from 23 pin 15 khz port at the same time on my A4000, but I usually am using regular NTSC modes.
Maybe the problem is that you are using a indivision only resolution?

if you use an exotic indivison only mode, it may not show up on the 23 pin port, or at least something you monitor may not be able to display.
I suggest trying a NTSC (or PAL) mode, something like 640x400 and test it.