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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 10th Mar 2017, 9:21 pm   #1
veedub565
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Default CUB Monitors

Hi, I've got a BBC model B and I've got two CUB monitors (with two boxed new replacement tubes)

Obviously I'm using one monitor with the beeb. Any suggestions what I could do with the other? could you dual screen a beeb?

It's a bit of a shame to leave it to rot in the shed.
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Old 10th Mar 2017, 9:25 pm   #2
veedub565
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Default Re: CUB Monitors

I think I need a BBC Master, or an Electron just to use up the othe rmonitor you understand. And maybe then network them together.
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Old 10th Mar 2017, 9:28 pm   #3
TonyDuell
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Default Re: CUB Monitors

Get a second Beeb? And set up Econet?

There is no sensible way to run 2 monitors from one BBC micro. There's only one video circuit in there, and only just about enough RAM for that.

The BBC RGB output is TTL level. As is the input on the Cub used with said machine. So you are limited to 8 colours (including black). But I seem to remember there are internal links on at least some Cubs to have analogue RGB in (heck, there was a Cub with an internal PAL decoder, but I've never seen that one). So you could probably use it as an analogue RGB TV-rate monitor.

Or drive it (TTL levels) from, say, an SAA5243 chip. That chip + a 6MHz clock + an 8K SRAM chip (6264) will give you teletext-like video output (coloured text and block graphics like MODE 7 on the Beeb) from anything that can provided an I2C bus. I am pretty sure you could bit-bang that with a BBC User Port, actually.
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Old 10th Mar 2017, 9:37 pm   #4
veedub565
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Default Re: CUB Monitors

Interestingly one of the monitors does have a BNC input marked PAL 75ohm. It's also got an audio input

Last edited by veedub565; 10th Mar 2017 at 9:44 pm. Reason: Additional info
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Old 10th Mar 2017, 9:42 pm   #5
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Default Re: CUB Monitors

It's a long time since I worked on a Cub (heck, the last Microvitec chassis I worked on was inside an Acorn Cambridge Workstation...). I am not sure if you have to fiddle with any links to enable the PAL decoder. But if you can sort it out, you could feed that from the composite video output of a VCR, DVD player....
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Old 10th Mar 2017, 9:52 pm   #6
veedub565
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Default Re: CUB Monitors

Definitly going to give that a try
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Old 10th Mar 2017, 9:55 pm   #7
Scimitar
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Default Re: CUB Monitors

The Cub does indeed have links to set analogue in. However, it then wants 5V p-p rather than the 1V you might have to feed it.

If you want to duplicate the monitors, it shouldn't be difficult to make a TTL buffer amp.
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Old 10th Mar 2017, 10:01 pm   #8
TonyDuell
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Default Re: CUB Monitors

Quote:
Originally Posted by Scimitar View Post

If you want to duplicate the monitors, it shouldn't be difficult to make a TTL buffer amp.
Isn't that called a 74LS241?

But actually, I suspect you could just parallel the monitors (wire each pin to the same numbered pin on the other monitor). The Beeb is not going to mind driving 2 TTL inputs. And reflections are much less of a problem on digital signals.
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Old 11th Mar 2017, 9:14 am   #9
JohnBHanson
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Default Re: CUB Monitors

I too have a PAL/TTL version of the monitor. The PAL decoder is an add on board that fits to the back panel of the monitor. The board also contains the sound amplifier. Actually there was a version that was PAL/TTL/RGB with stereo sound! the PAL/TTL version I have is a partially populated version of the board.
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Old 11th Mar 2017, 12:23 pm   #10
mhennessy
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Default Re: CUB Monitors

The models with PAL converters also have Brightness and Saturation controls, and a toggle switch to switch between PAL or TTL. And a volume control (and audio input on a DIN socket): https://pbs.twimg.com/media/CUNdH4CXIAEJpds.jpg

There was also a Spectrum version, but I've yet to see one in the flesh: https://www.flashbackgames.co.uk/Sho...s/IMG_2820.jpg

We had loads here - they were used as cheap preview monitors in video edit suites. And - sad to say - they were pretty poor. The Philips CM8833 gave much better results, and were somewhat more reliable too.

The ones with the high resolution CRTs were excellent when fed TTL RGB from a BBC Micro. Sadly, most of the ones we had at work were the standard-res CRTs, so no better (and often worse) than a domestic TV fed RGB via its scart socket. I left a handful in the WEEE skip last year. I'm cross with myself, because I'd forgotten that I have a horrible plastic-cased example up in the attic - complete with hi-res CRT - and could have transferred the good innards into the "classic" metal cube case for use with my BBC.

I've never tried Econet. My Master is "networked" () via a serial cable for transferring disc images to and fro - very helpful, given what's available out there. Frankly, in your position, I'd do as you suggest - get a second machine. Very occasionally it would be nice to have an original B to hand because not all software works on the Master.

All that said, if you need a fix of classic BBC Micro gaming, this is good: https://bbc.godbolt.org/

It's an incredible technical achievement (a complete emulator coded in Javascript, running on your browser). You have full access to everything on the "Stairway to Hell" archive via the Discs menu. Enjoy
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Old 13th Mar 2017, 6:57 pm   #11
red16v
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Default Re: CUB Monitors

Just to say we used these on our three rank stand lighting consoles - to display lamp settings etc. Very reliable I have to say.

We had another one, which must have had a pal input, with a reverse scan mod so that puppeteers with the puppets above their heads, could see see what they were doing in relation to the other puppets etc, think 'Muppets' etc.
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Old 13th Mar 2017, 8:18 pm   #12
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Default Re: CUB Monitors

The hi-res ones were excellent and had a lovely high contrast black tinted faceplate. At least one pottery-orientated panel builder here in the potteries used an embedded BBC card to run stuff as esoteric as automated kiln loaders and spray driers. Their cubs were on 24/7. I've fixed so many over the years and only have fond memories of them, easy to take apart, good results when adjusted properly, and reliable for the day (not sure when they were introduced but we had them at school in the early 80's). The ones used in potteries would vacuum-up the airborne clay dust by static attraction and it wasn't uncommon to find one with its case full of powder to a depth of 3 or 4 inches.
Most of the faults were standard for tvs of the day such as dry joints, high resistors in the smpsu, dried electrolytics and all the little problems that running one with open circuit capacitors can cause, eg overheated lop transistor, overheated frame chip, blown smpsu driver etc.
ISTR they used toshiba tubes which lasted forever except you often saw a burnt in image of a machine mimic diagram or some giant numeric readout when checking the greyscale!
The comprehensive service manual came in its own ring binder. I'm sure the circuit boards reminded me of some late Decca portables, I wonder if there was a cross-over of employees or suppliers as they were a Bradford company AFAIK.



PS here's a gratuitous screenshot of Bill Giles.
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Last edited by McMurdo; 13th Mar 2017 at 8:25 pm.
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Old 19th May 2017, 2:17 pm   #13
canonman75
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Default Re: CUB Monitors

Quote:
Originally Posted by McMurdo View Post
The comprehensive service manual came in its own ring binder. I'm sure the circuit boards reminded me of some late Decca portables, I wonder if there was a cross-over of employees or suppliers as they were a Bradford company AFAIK.
The guy who started the company, Tony Martinez (I think), used to work for Decca. It might have even been the old Decca factory!
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Old 19th May 2017, 3:05 pm   #14
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Default Re: CUB Monitors

http://www.thetelegraphandargus.co.u...ss_dies_at_81/
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Old 19th May 2017, 3:26 pm   #15
canonman75
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At least I got his name right!
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