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Monitors compatible for the BBC micro

Posted: Sun May 17, 2020 3:36 pm
by acornboy48
Hi,

I plan on getting a BBC micro but i would like to know my options for the display. Can i easily connect to a composite or vga monitor?

Re: Monitors compatible for the BBC micro

Posted: Sun May 17, 2020 4:05 pm
by rmbrowngr
I’d recommend a RGB to Scart cable and use with a tv. You can pick one on eBay easily.

If you have a monitor or tv with only hdmi, there are some recommended converters, or a project here in the forums to convert RGB to hdmi using a Raspberry Pi. https://stardot.org.uk/forums/viewtopi ... =3&t=14430

I wouldn’t go for composite as RGB to Scart has better picture quality.

I use an old Sony Triniton portable tv with RGB to Scart and the picture is just fine.

Re: Monitors compatible for the BBC micro

Posted: Sun May 17, 2020 4:07 pm
by tricky
Someone will be along with facts, but composite is probably OK, VGA needs a converter.
Most popular BITD was a CUB, but I prefer rgb scary.
Rgb2hdmi is great for HDMI if you have to.

PS posted at same time

Re: Monitors compatible for the BBC micro

Posted: Sun May 17, 2020 6:50 pm
by 1024MAK
acornboy48 wrote:
Sun May 17, 2020 3:36 pm
Hi,

I plan on getting a BBC micro but i would like to know my options for the display. Can i easily connect to a composite or vga monitor?
The answer partly depends on whereabouts in the world you are and what TVs/monitors you already have.

A standard BBC model B has the following video outputs:
  • The best picture is via the RGB outputs on a 6 pin DIN connector. The RGB outputs are 625 line, 15625Hz, 50Hz TTL level signal outputs. A range of Microvitec CUB colour monitors can be directly connected. RGB to SCART cables are also available, these use resistors to convert the TTL signal level to the SCART TV voltage levels. A lot of LCD TVs (but not all) will work with this arrangement. It is also possible to use a converter box / board to convert the Beebs output to VGA or to HDMI.
  • Monochrome composite video - via a BNC connector. This is a standard composite video suitable for any TV or monitor that has a composite video input and which can receive a 625 line, 15625Hz, 50Hz (CCIR System I) video signal. Note that as standard, this output is NOT in colour, only monochrome/ grey scale. This is good for the 80 column MODE 0 and MODE 3 video display modes. Colour can be added by soldering in a small capacitor at the expense of the clarity of the displayed picture.
  • UHF TV - via a phono connector. Also known as the aerial output. Most users no longer use this, as it is the least best quality output.
So if you have a TV that has a SCART socket and this SCART socket supports the RGB input mode, a SCART lead is what I would recommend.

Mark

Re: Monitors compatible for the BBC micro

Posted: Sun May 17, 2020 7:20 pm
by SimonSideburns
To add a few thoughts, back in the day I had a small 9" colour TV with SCART input on the back and I had my Beeb's RGB output connected to that.

If I wanted a larger screen display I plugged the Beeb into my 22" Grundig TV via the aerial socket which gave an OK picture, but not what I'd call a fantastic one. The larger size of the screen sort of made 80 column modes bearable.

A while later I became the owner of a Philips CM8833-II monitor with a 9-pin D-SUB connector on the back and connected my Beeb to that via the RGB output. Pinouts are available online as it seems to be a common video connector. I still have that monitor, but I don't use it all that much at the moment.

A year or two ago I bought a CUB monitor. I've always wanted one as I used them at school, but didn't ever find a working one at a reasonable price. They are the simplest way to connect your Beeb to a display using a straight-through cable from the RGB socket to the one in the monitor. That is the monitor I'm using with my Beeb now.

Re: Monitors compatible for the BBC micro

Posted: Sun May 17, 2020 9:33 pm
by Kazzie
SimonSideburns wrote:
Sun May 17, 2020 7:20 pm
A while later I became the owner of a Philips CM8833-II monitor with a 9-pin D-SUB connector on the back and connected my Beeb to that via the RGB output. Pinouts are available online as it seems to be a common video connector. I still have that monitor, but I don't use it all that much at the moment.
The earlier Phillips CM8833 Mk1 used a round 8-pin connector for TTL RGB, but it too works great with a suitable cable. I use it with my Beeb or Archimedes, interchangably. (Sometimes I use the Beeb through the composite input and the Archimedes through the SCART RGB, so that I can toggle between them easily using the switch at the front.)

Several Acorn-branded monitors (AFK-11, etc.) were of course rebadged monitors made by the likes of Phillips.

To see what Acorn themselves had to say about connecting their machines to various monitors, see http://chrisacorns.computinghistory.org ... AN/249.pdf

Re: Monitors compatible for the BBC micro

Posted: Mon May 18, 2020 1:36 pm
by guesser
1024MAK wrote:
Sun May 17, 2020 6:50 pm
Most users no longer use this, as it is the least best quality output.
That's a very generous way to put it 😂

Re: Monitors compatible for the BBC micro

Posted: Mon May 18, 2020 2:50 pm
by acornboy48
I'll probably go for a SCART tv with RGB support.

Thank you guys!

Re: Monitors compatible for the BBC micro

Posted: Mon May 18, 2020 3:25 pm
by Naomasa298
SimonSideburns wrote:
Sun May 17, 2020 7:20 pm
To add a few thoughts, back in the day I had a small 9" colour TV with SCART input on the back and I had my Beeb's RGB output connected to that.

If I wanted a larger screen display I plugged the Beeb into my 22" Grundig TV via the aerial socket which gave an OK picture, but not what I'd call a fantastic one. The larger size of the screen sort of made 80 column modes bearable.

A while later I became the owner of a Philips CM8833-II monitor with a 9-pin D-SUB connector on the back and connected my Beeb to that via the RGB output. Pinouts are available online as it seems to be a common video connector. I still have that monitor, but I don't use it all that much at the moment.

A year or two ago I bought a CUB monitor. I've always wanted one as I used them at school, but didn't ever find a working one at a reasonable price. They are the simplest way to connect your Beeb to a display using a straight-through cable from the RGB socket to the one in the monitor. That is the monitor I'm using with my Beeb now.
I loved my CUB. When my multisync failed, I switched the CUB from TTL to RGB (is that right?) and used it with my A3000 by sticking wires in the appropriate pins.

Re: Monitors compatible for the BBC micro

Posted: Mon May 18, 2020 4:08 pm
by Kazzie
Naomasa298 wrote:
Mon May 18, 2020 3:25 pm
I switched the CUB from TTL to RGB (is that right?)
Probably not - "TTL" would indicate RGB values switching between 0V and 5V, whereas regular Analogue RGB is closer to 1V. That is, they're both varieties of RGB. (But I can't speak with any authority on CUB monitors, though.)

Re: Monitors compatible for the BBC micro

Posted: Mon May 18, 2020 4:45 pm
by 1024MAK
Kazzie wrote:
Mon May 18, 2020 4:08 pm
Naomasa298 wrote:
Mon May 18, 2020 3:25 pm
I switched the CUB from TTL to RGB (is that right?)
Probably not - "TTL" would indicate RGB values switching between 0V and 5V, whereas regular Analogue RGB is closer to 1V. That is, they're both varieties of RGB. (But I can't speak with any authority on CUB monitors, though.)
RGB literally means that separate signals on individual channels (for what was the three electron guns in a CRT for the three different coloured phosphors) are supplied to the TV or monitor. “RGB” itself does not define the signal level.

The following are (were) the most common variations:
  • Analogue RGB via three {sync on green channel} or four {separate sync} individual co-ax cables, typically up to 1V peak-to-peak.
  • Analogue RGB via a multicore cable via a SCART connector, typically up to 1V peak-to-peak.
  • TTL RGB (as used on various computer systems including the Acorn BBC / Electron machines (total of eight available colours), digital TTL logic level signal, colour off being less than 0.8V, colour on being between 2V and 5V.
  • TTL RGB with additional intensifier or brightness signal (such as CGA or the ZX Spectrum 128 machines)(total of fifteen or sixteen available colours), colour off being less than 0.8V, colour on being between 2V and 5V.
    VGA - uses analogue RGB but most systems can’t work with TV frequency video, typically up to 1V peak-to-peak.
A Cub monitor can accept Analogue RGB or TTL RGB depending on the model and it’s configuration. For Cub monitors intended for use with a BBC Micro, they would have TTL RGB inputs. But analogue versions were also available. It is possible to convert some that have TTL RGB inputs to accept analogue RGB inputs.

Mark

Re: Monitors compatible for the BBC micro

Posted: Mon May 18, 2020 4:48 pm
by Naomasa298
1024MAK wrote:
Mon May 18, 2020 4:45 pm
It is possible to convert some that have TTL RGB inputs to accept analogue RGB inputs.

Mark
IIRC,it was just some jumpers that needed switching.

Re: Monitors compatible for the BBC micro

Posted: Tue May 19, 2020 3:08 pm
by SimonSideburns
Naomasa298 wrote:
Mon May 18, 2020 4:48 pm
1024MAK wrote:
Mon May 18, 2020 4:45 pm
It is possible to convert some that have TTL RGB inputs to accept analogue RGB inputs.

Mark
IIRC,it was just some jumpers that needed switching.
Yes, that's pretty much it. I was fortunate enough to get one with those jumpers and I connected the jumper pins to a switch that I fitted on the back of the monitor to toggle between analogue and digital as my Beeb has a Chameleon Colour Board which can change the 8 colours to any from a palette of 4096. The article about the Chameleon Colour Board detailed the procedure of changing the jumper positions.