Retro computing and monitor output part 2

As per part 1 , I’ve been trying to find a solution for display output for ‘all’ of these old computers (so far two Amiga 500s, an A600, an A1200, a ZX Spectrum 48K, an Atari 800XL and an Acorn Electron). Basically I wanted a monitor or adapter and monitor that will ‘display any of the old computers’ in my collection. I really did not want to have to keep a big TV on my office desk just for these old computers. Up to now I couldn’t quite do it for all my old computers. I had an old AOC 17 inch 4:3 monitor in my lab with various adapters hooked up to it for display;

  • A composite/svideo to VGA adapter (I actually have two of these). Places like amazon and aliexpress have heaps of these types of devices.  I can use the adapter for svideo output from an Amiga A520 modulator (modded to produce svideo) and it looks great. I can also use it for svideo output from an Acorn Electron. Again it looks great. But using with my ZX Spectrum 48K or Atari 800XL shows a jittery/bouncy black and whitish mess (this is with composite or svideo).
  • A Gonbes GBS-8200 adapter. I can use this with the RGB output of my Amigas. It looks generally great, but it is prone to ‘sparkling’ artifacts on the screen (note, I did change the power supply input to use a tantalum but still get some ‘sparkling’) and seems to have strange ideas about antialiasing. It is amazingly good for about $25 though. I can also use it with the RGB output of the Acorn Electron. Again its generally a really good image. It has RGBS and component inputs which effectively rules out using it with the Spectrum or the Atari.

So none of these devices was able to do the display output of the Spectrum or Atari 800XL. The only screen I have in the house that did do those correctly was a Sony Bravia TV.

So I was still on the search for something else. Often the Amiga forums mention monitors that do the elusive 15kHz/50Hz RGB into their VGA connector (technically the minimum for VGA is 31kHz/60Hz). These monitors are rare and often the manufacturers don’t even mention this capability in their specs. There are a few Dell monitors that do this mode, and importantly there are a few Dell monitors that have this capability AND have composite and  svideo inputs. Sadly there are no new Dell monitors that do svideo. I don’t think there is any new monitor in 2015 that does svideo, but svideo is really good to have for these old computers. Generally you can hack an old 80s computer to generate composite (instead of RF out) … and quite a few can be modified (by finding the chrominance output) to generate svideo. The picture quality improvement over composite is quite noticeable.

So Dell have made (in the past) some nice monitors that do composite, svideo, vga (including supporting 15kHz/50Hz) and DVI etc. Often the older 16:9 24 inch 1920×1200 ones had these features … and the Dell 2001FP had it too. The 2001FP is a 20 inch 1600×1200 4:3 monitor. 4:3 is really nice to have for old systems as they obviously put out non widescreen images … and if you use a widescreen monitor with an old computer you kind of hope that it has some decent way to lock the display to 4:3 mode. Anyway, the 2001FP is natively 4:3. One came up for sale 2nd hand, it wasn’t too expensive,  and I found a reference on an Atari ST monitor wiki to make sure the monitor was made before June 2005 (as Dell used a different OEM after this I think … and importantly the ones made after June 2005 don’t support 15kHz/50Hz on VGA). This second hand one was September 2004.

The 15kHz/50Hz into the VGA input is not perfect though. There are two oddities;

  • The screen output of an Amiga running straight into the VGA input is shown offset to the right. You then have to fiddle with the OSD to adjust the horizontal position (you just have to adjust it by ‘one notch’ and the picture jumps into the middle where you expect it to be).
  • Sometimes the Amiga output is shown with a pinkish or greenish hue. Turning the monitor off and on rectifies it.

So that’s a little annoying, but at least it can display it! then of course it does composite and svideo and DVI too. I did not know whether it would support the composite output of the Spectrum or the svideo output of the Atari … but I am happy to report it does both just fine. So far I have not figured out RGB output from the Electron (ie. the Dell won’t display it), but I may need a sync seperator or fiddle with resistors (as the voltages are not VGA). Regardless, the svideo out of the Electron looks very good on the 2001FP.

So I finally have a monitor that can display everything … and 1600×1200 is actually quite nice via DVI from a modern computer too.

The only other really annoying thing about this 2nd hand monitor is that the LCD panel has two finger print sized smudge marks in the middle of it … which I have read is some sort of LCD burn in (the monitor is over 10 years old). I have tried various things to try to get rid of them .. but they are still there. For now I am putting up with it.

I guess using an 11yr old monitor is not for everyone. In my research, a few things came up

  • Use a TV. In 2015, you probably won’t find a new TV with s-video, but composite is still around. But it is difficult to find anything less than 32 inches … and I really didn’t want a 32 inch TV on my office desk. I have read that some TV’s will support 15kHz/50Hz on their VGA input … but its one of those undocumented things … that you really have to scour forums trying to find someone else hinting that ‘it works’
  • Find a modern monitor that can do 15kHz/50Hz on its VGA input and has composite. I’m not sure if I ever found one of these in my research. There seem to be a few that do 15kHz /50Hz but don’t have composite.
  • Get an XRGB Mini. These aren’t particularly cheap (around US$300), but they are designed for the retro community in general … unlike just about every other adapter out there. The XRGB Mini is really designed with progressive scan PAL/NTSC video in mind … which is exactly what you want for old systems from the 80s and 90s. Ultimately, it was a lot of money to pay for something that I would ‘hope’ could handle the Spectrum and Atari 800XL video output…. but might have been a good ‘long term investment’.
  • Get a Commodore 1084S or 1081 CRT Monitor. I actually have one, but the flyback is dead. Future project to get that going again. In some ways these are the ideal monitors for 80s/90s stuff (no svideo though).

And why is the Spectrum and Atari 800XL so problematic for these cheap composite/svideo to vga adapters? Who knows? I can  imagine these cheap adapters are made with interlace PAL/NTSC in mind … and also the PAL video output of these two systems may be on the edge of what the PAL definition defines. That was fine in the era of CRT screens where screens were ‘forgiving’ on what ‘video’ they had on their inputs, but modern devices (like these adapters) probably only understand a more narrow definition of what PAL and NTSC is.