Vintage Computing & Consoles BBC Micro; Teletext Adapter, Winter Project

Ah, I'm pleased you've got one of these - brings back some memories of Tech. Investigations, that!!

Very nice! As someone who went to primary school in the 80s whenever I see a BBC Micro I have to type the following:

10 PRINT "Mr Brendon smells of wee!"

20 GOTO 10 

Run_

Hi All. I still have a working BBC master here. But of more interest to Crusty is I think I have two Teletext editing machines. These are in metal cases with special keyboards. Inside the metal case you will find a BBC Master board. These again are ex Sky from the analogue days used go generate teletext content. I have sat on these for about 25-30 years. I will try and locate one to take a photograph.

Couldn't resist, into the garage, so here is the Teletext editing machine pictures. Inside you will see it is a BBC Master computer with the software/firmware on the Master ROM Sockets. Going off memory it was connected RS232 to a Teletext video generator rack mount unit. Out of this came blank video with teletext lines which then fed a Teletext data bridge. This bridge added further teletext live data and subtitles for the running program. This is all from my memory from 30 years ago. It was still used when we went to digital TX some of the units being up dated.

I will check/work through the PSU before applying power. Common fault I remember with both the BBC B and Master computers was a dead power supply due to the 330k resistors going open circuit.

Now to find a 625 line RGB monitor.

@hurty ooh! Very nice.

If Chris CrustyTV doesn't want them I'd certainly be interested. 

You could probably start a VRAT VBIT2 server with this.

Posted by: @Anonymous

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f Chris CrustyTV doesn't want them I'd certainly be interested. 

I think you're being a bit presumptuous assuming Adrian is offering them up. When he said, "interest to Crusty" I think you'll find he was talking of "technical interest" not acquisition interest, nowhere has he said he is offering them up. However, If I am incorrect, and he is, then of course I'd like them for the growing teletext section of the museum, but let's not get ahead ourselves.

Posted by: @hurty

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Couldn't resist, into the garage, so here is the Teletext editing machine pictures. Inside you will see it is a BBC Master computer with the software/firmware on the Master ROM Sockets. Going off memory it was connected RS232 to a Teletext video generator rack mount unit. Out of this came blank video with teletext lines which then fed a Teletext data bridge. This bridge added further teletext live data and subtitles for the running program. This is all from my memory from 30 years ago. It was still used when we went to digital TX some of the units being up dated.

Fascinating insight to the broadcast side of things Adrian, look forward to seeing how you get on with the power up. I'm certainly going to be cautious when my micro arrives and the Teletext adaptor too as that has its own PSU.

Posted by: @hurty

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Now to find a 625 line RGB monitor.

Exactly what I need to do as well, one of these would be cool.

Went through the power supply capacitors and nothing really wrong but as I always do I change the primary side low voltage capacitor, sometimes referred to as the "start up" capacitor, 220uF 25V. It was down to 180uF which indicates it is starting to get tired. Powered up the main unit and you get a 625 line blank raster output. Plugged in the keyboard and it now boots up as a full teletext editor. The UHF output is colour and the video output is monochrome. This was normal for the BBC micros. I need to add a capacitor to put the PAL subcarrier back on the video output. Never understood why they didn't do that on the video output?  Now where would I have the diagram for this as the internet wasn't around in those days!  Some pictures for you.

I will look at the 5 1/4 inch disk drive next as I assume it will have no rubber bands left in it.

I don't know how useful this device will be as it used a serial output to another unit that generated the teletex video lines. I have no idea what it will save to disk but assume it will be DFS or ADFS but no idea in what format, hopefully something useful.

I will see if I have a second unit which I think I will have. I put the post up on here as teletext was Crusty's interest. If I have a second unit I will most likely be passing on and it was Crusty I was thinking of. Wayne I have noted your interest too. Let me do a final search for this stuff, it needs to go to someone who will use it as intended, I have sat on them for over 25 years.

When teletext started it was rare to see a set fitted with a text decoder. I read the Television magazine articles on it as I did all the Philips VCR articles. It was an interesting time at the start of my TV and the VCR career, I just couldn't get enough of all this stuff 1980 was the start of me seeing teletext equipped sets. at the end of 1980 I'd joined the BBC later joined Telefusion as they wanted VTR experience but whist there one of my jobs was installing Prestel Terminals. Some of these were domestic sets equipped with both Teletext and Prestel, same decoder, these being fitted with a post office jack plug for the telephone line. Telefusion sold a lot of Sony I think KV-2206 or 2216 sets that had both Teletext and Prestel fitted but people just got them for the Teletext. Had to go around a few customers to remove the post office lead as people didn't like it hanging out of the back of the set

When I joined Thames Television I was involved in maintaining the Oracle equipment, timing is very important and downstream video processors had to be set correctly not to corrupt the end of each teletext line. I had to do the same at Sky. Most of the knowledge I used was from me learning about the TV receiver end of teletext.

I feel we will be visiting R. T. Russell's page on BBC basic?

Enjoy

Crusty forgot to add I have a Ferguson MC05 somewhere which is almost identical in operation to the MC01. I have a Micro Video RGB terminal somewhere?

Hi Adrian, Wow! That is a blast from the past and a real treat to see.

As you may be aware, this year I have been refocussing the museum and have moved most of my first generation colour, and hybrid sets to other collector.

In place, I've been adding a lot of late 1970's to mid to late 1980s TV's, many with teletext. My recent projects on the Rank Arena Teletext TV and the battles with the Labgear 7026 are evidence of that intent. I think at last count I had 12 text sets, and I'm collecting the Philips Teletext TV with thermal printer this weekend.

One side of the museum is now going to be fully dedicated to teletext era, TV's Set-Top boxes and anything else I can find, the BBC micro and Teletext unit being the most recent sideways addition/project. The other side of the museum is still early to mid 70s, UK and continentals.

If you do intend to pass the Softel on, I would certainly like to give it a safe home here and would endeavour to learn how to put it into action. I'm hoping my background in IT will stand me in a good position to achieve this. I'm also hoping one day to obtain viewdata sets, but that is likely a much harder task than finding first gen colour TVs, then again I never thought I'd find a 4K or one of these Philips Teletext printer TVs, so Maybe I will find a viewdata set.

Hi Crusty, I could see where you were going with your TV collection. I have a couple of sets here to move on, one being a Philips G8 and the other a Ferguson 2000 set. I will be keeping the RR Baird 2000 set now I know what it is thanks to yourself, that set has puzzled me for 10's of years.

I have seen thermal printers on sets but these were usually Farmers and Travel Agents Prestel sets, sometimes an external plugin printer. I have had a look at the floppy drive and there is noting to go wrong with it. No rubber components, stepper motor metal connected to the pickup head and a direct drive spindle motor made by Teac. I have found some 5 1/4 master floppy's and have some blank discs. If you look at the bootup page you will see you can set the serial board rate, parity and bit length. Host is Signet which cannot be changed. I think this was the unit the pages were sent to that produced the Teletext vertical interface lines. It was this unit that gave the most trouble, think it ran on Unix, reboot first and if things were not coming back you would be typing in some command lines to get it going again.. Protocol is Astet or Aston, Aston is more familiar to me as character generators use it. Would be nice to see if the Raspberry Pie could be made to do this. What do the Rasberry Pie guys use for generation of their text pages, do you know or have a contact there? 

Could I ask Wayne, what your interest in this unit is? I'd like to know.

This unit is in Wireless World in 1988 as the BBC's new Teletext generators offering more functionality. I wonder if when the BBC bought these that there was a BBC Master sat in there.

More pictures for you to gloat over

Enjoy

Until I sort out a suitable monitor, I plan to connect the Beeb to my 10" roadstar bench TV. I don't want to use the UHF out of the Beeb but RGB, so will go via that to SCART. A while back and lucky for me, a closing TV shop contacted me and donated their period cable stock, many times it has come in handy, especially now. On the rack was a 6-pin DIN to SCART cable, just the job. Edit; looking at this cable, I now see it is not correct, but the question still stands.

 I'm hoping those in the know will be able to confirm or refute this, I need to add voltage divider resistors of around 220R to bring the TTL voltage level down to around 1V. True or False?

Posted by: @hurty

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Hi Crusty, I could see where you were going with your TV collection. I have a couple of sets here to move on, one being a Philips G8 and the other a Ferguson 2000 set. I will be keeping the RR Baird 2000 set now I know what it is thanks to yourself, that set has puzzled me for 10's of years.

I used to have four 2000s, I've only one 19" 2K left and a 19" 710 series Baird, I'm even considering letting those go now. Most of the 3000's have now also gone, just two left. I've still a few more early 70s to move on, then I should be done. My G8 doesn't seem to generate any interest. Glad you're hanging on to the RR 2K, I think it's the only one left!

Posted by: @hurty

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No rubber components, stepper motor metal connected to the pickup head and a direct drive spindle motor made by Teac.

That is a result, built to last

Posted by: @hurty

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Would be nice to see if the Raspberry Pie could be made to do this. What do the Rasberry Pie guys use for generation of their text pages, do you know or have a contact there? 

Only scratched the surface, with Pi, I can see a deep dive coming up, plenty of forums with clever folk, they've even got a Pi now that can do 405-line!

Posted by: @hurty

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think it ran on Unix,

Ah-ha my bread and butter, I was a System V unix admin for 10-years.

Posted by: @hurty

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More pictures for you to gloat over

Those 5.25 drives take me back, I can even smell them 😆 

That is some cutback in sets. I thought you where going to go down the Thorn line as they were so ahead of everyone else from their very first colour set.  The RR 2000 has just stuck with me, didn't really want it when it came into my possession but very happy with it now.

The drive was a surprise when I opened it, hopefully nothing to worry about there. I have dug out my BBC and BBC Master manuals. I don't remember a problem with the RGB + Sync output levels of the BBC's  into the Ferguson, I'm measuring 3.5 volts unterminated out of the RGB connector. Would need to do a bit more checking as the scart will be terminated at 75 ohms and I don't know what the RGB source impedance is without the schematic. You may just need the 330 ohm resistors in series? I have my BBC and BBC master manuals here.

I have checked in the house attic and I have two more text generators and so far one more keyboard. I have to do a bit more checking yet.

Posted by: @hurty

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That is some cutback in sets. I thought you where going to go down the Thorn line as they were so ahead of everyone else from their very first colour set. 

The cull sounds bad, but I had so many Thorn sets it has hardly made a dent, and Thorn is still hugely represented. For example, the collection still has a 2k, 3k, 3.5k, 4k, 8k, 8.5k, 9k, 9.9k, TX9, TX90, TX10, TX100. That's almost their entire run, I'm just missing 8.8k, 9.6K and 9.8K. What's gone/going are all the valve dual standards, sets from other manufactures, duplicates and non Thorn sets I have lost interest in. The collection at present covers 1968-1988.

Posted by: @hurty

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I'm measuring 3.5 volts unterminated out of the RGB connector. [..]  You may just need the 330 ohm resistors in series?

Indeed, the 3.5V signal level is too high, so the series resistors are required to get that down to around 1V to avoid all sorts of problems. It's all sorted now and have confirmed DIN to SCART requirements. 👍 

I've uploaded all manner of documents relating to the BBC Micro into our data library. One superb document is the BBC Micro Mainboard Circuit which is searchable and colour, you may find that of great use as did I. As and when I find more, they will be added.

Great project, you will soon be building a GOTEK for it. I have a similar teletext adapter connect to mine using a Pi and VBIT2. 

A great recomendation for a sideways rom ram board Are the IFEL board made by Steve in Plymouth.

The main unit has arrived, cosmetically looks to be in superb condition, let's hope the internals are as good. No power will be applied until I've had a look at the PSU. Lots of games too, and a word processor. Sid's eager to get the screwdriver on it.

Tapping on the keyboard gave me a huge nostalgia trip, not because I had a Beeb or any other, I completely bypassed this era of home computing because at 16 I was working in I.T. on ICL mainframes, as my day job. No, the nostalgia was the tactile feel, sound and response from the keyboard, it reminds me so much of the ICL 7500 series, in particular the 7502 terminal I used to use. I had me wanting to reach for the punch tape machine.

Hoping the Teletext adaptor will arrive today or at least over the weekend.

Time to open it up and have a look, finger crossed.

p.s.

Tape player works

The Internals

PSU has 4th Feb 1983 stamped on it, next, open that up and have a look to see if the RIFA's have been expelled, check the electrolytics and the 330K resistors.