QL-VGA

I have been trying out a new video converter called QL-VGA from Marcel Kilgus.

QL-VGA in its packaging
Opening the box in which QL-VGA was delivered

QL-VGA lets you connect  a Sinclair QL’s RGB video output, from the 8-pin DIN socket, to a monitor or TV with a computer VGA video input.

For a long time, connecting a QL to a modern monitor has been a problem in two respects. Firstly, the QL RGB video output is not suitable for use with VGA inputs without adaptation and of course, if we connect to a TV or monitor with a SCART connector most monitors will lose a character or two at the edges of the picture in monitor mode because of the QL overscan on the video signal. Some of us have had a degree of success using the QL with some of the HDMI video upscalers available on Amazon and eBay, although results vary – I got a decent picture with a QL and one of those with a cheap TV set via its HDMI connection, but another screen gave me poor results. I know of a few users who can’t get a picture at all with those devices.

For some time, I’d petitioned the QL hardware providers to produce a gadget like this for use with the QL, to connect a QL to a VGA monitor. And finally, here it is.

The QL-VGA device takes care of adapting the signal and scaling it to fit the monitor display resolution. I’ve been able to use it on a 1920×1280 monitor, an older 1024×768 SVGA monitor and a TV with a VGA input for a computer. With excellent results – the QL display fills the screen without losing any characters and the display is as good quality as you’re likely to get from the screen concerned. Rock steady, all 512×256 pixels visible and filling the screen.

Picture of the video cable.
Video cable.

No video driver software is required on the QL – it is just plug and go. One of the boards contains an FPGA chip which does much of the work.  The device works in both 4 and 8 colour QL display modes. It copes well with changing mode on the QL – just a momentary slight flicker, no worse than you get normally when changing mode. No instructions were included with this prototype, but it was pretty obvious and intuitive how to connect it all together.

I’ve tried this with four different screens so far, and it works well on all four. With two of the monitors, I had to press the AUTO setup button on the monitor to accurately centre the display, but that’s no trouble (on one it was just a pixel or two offset, going by the borders of the monitor mode windows, while on the 1024×768 monitor, it was offset a lot to the right – I think it had been previously set up for my Aurora system).

Power cable.
Power cable.

This is a prototype of the QL-VGA, of course, it is not available to buy yet. The first prototype did not work with a UK QL (although it worked fine with a German Samsung QL) due to very minor differences in the video signal produced by the CLA2345 chip in the Samsung QL and the CLA2310 in a British QL. Once Marcel made small adjustments to the QL-VGA and sent me an updated board, it then worked immediately.

QL-VGA consists of two small blue circuit boards (production versions may have a different colour circuit board) attached by three 14×2 pin connectors, facing each other.  The length and width of the prototype are about 100mm x 50mm, with a combined deth of about 50mm. The VGA socket sticks out a few mm from the board on one end. Please note, this is a prototype board, so the final version may differ a little.

It is supplied uncased, but has 4 drilled holes on the base board, which may allow it to be mounted in a small case if you wish.

QL-VGA used with a 15 inch VGA monitor
QL-VGA used with a 15 inch VGA monitor

There are three user connectors on the board, plus a couple of connectors for use in programming and testing. The user connectors are:

  1. A VGA male to male video lead from the board to the monitor.
  2. A 8-pin mini-DIN socket (similar to an s-VHS connector) to connect to the QL’s 8-pin DIN. A ready-made video lead is supplied with the board.
  3. A round “barrel” power connector. Connect this using the USB power lead supplied – any conventional 5V USB phone charger can be used, most of us will probably have a spare one lying around. Marcel supplies a power lead, but not the power supply. QL-VGA doesn’t draw much current. Remember that the power supply must have a USB socket on it, for Marcel’s power lead to plug into.

This means that this little board has three leads attached, all trying to pull the circuit board in a different direction! Be aware if using it uncased that there are exposed solder contacts on both sides of the device, so best not to place it on a conducting surface of course.

At switch-on, it takes a second or two for the picture to appear. If there is a problem, you may see the device show a bold QL-VGA logo on the screen to indicate it’s working, but can’t detect an input signal for some reason. At first, I wasn’t aware that three LEDs on the board can also show that there is no suitable input detected – the brightness of one of them varies depending on whether or not it’s detected a suitable signal.

QL-VGA displaying on a 1920×1280 resolution monitor

There’s a small switch on the lower board, which lets you cycle between QL and ZX-128 (Spectum) input video signals. I don’t know if the ZX-128 mode has been fully implemented yet – it’s meant to zoom the ZX display to fit the screen. I don’t have a Spectrum nowadays, so I tried the switch while a QL was connected. It didn’t break it, just gave a weird zoomed version of the QL display.

There are some commercially available VGA to HDMI converters. It would be interesting to see how such a connection would work (OK, a mess of cables, perhaps, but aren’t we used to it with QLs?).

As I write this, the QL-VGA has been in use for less than a day on my QLs here. One is a QL with Gold Card and QLEA ROM switcher, while the other is an unexpanded BBQL. Works well on both – power drawn on the first QL seemed to make no difference at all to the QL-VGA. Not that I’d expect it to – the board would only draw about the same amount of power from the QL video socket as a regular monitor would. The board seems to run quite

cool after being on for a few hours, so probably draws little power.

Depending on the aspect ratio of the video monitor used, the display scaling may stretch shapes on the screen – which is only natural, because the QL display is stretched to match the monitor as much as possible. As an example, on my LG 1920×1280 monitor, circles are stretched w:h ratio about 1.20 (only calculated roughly and quickly by measuring with a ruler!), while the 1024×768 w:h ratio is about 0.9. While this is unavoidable with the screen stretching involved – 1024×768 is twice the horizontal QL screen resolution and 768 is three times the vertical resolution – you need to be aware of it if working with graphics on the screen, for example. In practice, with text especially, the scaling is so good that you don’t really notice it until you see large circles. To some extent you can predict what will happen by dividing the monitor resolution with the QL resolution – my 1920×1280 monitors are 3.75×5 times QL resolution.

At long last, we can connect a QL to a VGA monitor. These are so common, and you can get hold of plenty of older 14 and 15 inch screens quite cheaply second hand, which make a perfect day-to-day display for the QL. I’ve become over-attached to a QPC2 emulator on a PC, partly because of not having a comfortable VDU for my two QLs. This situation is now rectified. It’s one thing to work with a monitor which is an exact multiple of the QL display resolution, but I’m so impressed with the quality of the display even on a monitor which is not an exact multiple of the width.

I can’t really think of any negatives with this board, other than all the cable floating around (used to that with a QL) and the fact it’s uncased (easy to rectify I guess). You need to provide a 5V USB power supply such as a spare phone charger, which you may have lying around anyway. Provided the price is affordable (i.e. not more than the monitor itself) it’ll be a popular purchase.

You can read about the development of QL-VGA in two articles on Marcel’s blog:
https://www.kilgus.net/2019/04/21/ql-vga-part-1/
https://www.kilgus.net/2020/01/08/ql-vga-the-second/

No price announced for the QL-VGA adaptor board yet, and there is perhaps still a little uncertainty over availability due to the possible disruptions to board and component supplies due to the ongoing Coronavirus situation. Marcel will no doubt be anxious to get sales going once he’s confident it’s ready to go, so keep an eye on the usual sources of QL-related news, such as QL Forum, QL-users mailing list and the QL Facebook groups. I predict this will sell like the proverbial hot cakes!

4 thoughts on “QL-VGA

  1. Who to thank first?! Marcel for a great device or Dilwyn for a clear and comprehensive write-up? My thanks (and greetings) to both
    John in Wales

  2. Thank You Dilwyn for a great review and of cource Marcel for a great device (again)! Happy to get my QL-VGA at 24th ZX Team Meeting at the end of March 🙂

  3. Pingback: QL VGA Case | Dilwyn Jones Sinclair QL Blog

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