Viewdata Adaptor/Terminal

[SunSPARC]

Yes, the Philips (G11) and Thorn (9650) both had models fitted with the same Mullard derived Teletext/Viewdata/Modem(LCU) combination around 1979, before "LUCY" was released. The Viewdata Acquisition and Control (VAC) board employed a Signetics 2650 Microprocessor and 2651 PCI to interface with the (PYE TMC designed) modem unit at that time.

If you haven't seen it already, this may be of interest - https://www.vintage-radio.net/forum/....php?p=1559486

(Since then I have, I believe, proved that the modem is faulty, but currently further fault finding has had to be paused due to personal issues)

[TonyDuell]

I have a pair of Philips Prestel/Viewdata sets in my collection.

The older one is the one shown in the back of some 1980s Philips databooks to advertise their data subscription service. From what I remember, apart from the power supply the insides consist of a stack of 3 or 4 boards. It certainly uses the SAA50x0 teletext IC chipset, one board is essentially a teletext decoder/display module. Another board is the modem with connections to a Plug 505. There's an 8048 to control it think.

I can't remember if it uses the SAA5070 Lucy chip, but I think it does.

One odd feature is that the original colour monitor (which I don't have) was apparently a modified portable TV set. A TV set with a live chassis. As a result there's a secondary winding on the mains transformer in the viewdata set gving about 220V AC wired to a socket on the rear panel. This is used an isolated mains supply for the monitor.


The later unit uses the SAA5020 timing chain and SAA5050 character generator, but none of the other chips from that family. It's controlled by a Z80. Oddly, theres is no serial chip anywhere in the thing. There's a second board which is clearly the modem, this contains an 8048 and (I think) a Texas Instruments modem chip. Certainly no Lucy.

[Philips210]

Back in the mid 1980s I considered building a Viewdata system using the three Mullard boards but the project didn't get off the starting blocks.
Mullard were always very obliging with technical information and never charged for it. There was a Mullard publication I received entitled" LSI Circuits for Teletext and Viewdata: The LUCY Generation" which was a very useful reference. I sadly no longer have this data and have been trying to locate a copy for a number of years. I seem to remember there was a circuit to provide random characters for testing teletext decoders.
I don't suppose anyone has a spare copy by any chance?

Regards,
Symon

[cmjones01]

Originally Posted by TonyDuell

One odd feature is that the original colour monitor (which I don't have) was apparently a modified portable TV set. A TV set with a live chassis. As a result there's a secondary winding on the mains transformer in the viewdata set gving about 220V AC wired to a socket on the rear panel. This is used an isolated mains supply for the monitor.

When I was a student in the early 90s, a friend came upon a quantity of viewdata terminals which I think were ex-travel agent units. There were some older Philips ones and newer Sony ones. The older Philips ones had a separate "computer" module with the monitor sitting on the top and they were definitely SAA50xx based. I ended up with one of the monitors and it was a modified Philips 14" portable set, KT3 chassis I think. The colour decoder card had been replaced with a special RGB input board, most of the controls were blanked off with a piece of black plastic, and the mains lead had an IEC C14 plug on it with only live and neutral pins present. The set had a distinctive Philips C-core isolating transformer fitted in the bottom of the cabinet, which a contemporary KT3 chassis television wouldn't have had.

I fitted a PAL decoder card (sourced, of course, from Sendz components) and added the missing controls. The set did good service as a workshop/computer monitor for a number of years. I experimentally replaced the CRT with a high resolution one from an EGA PC monitor, but it never worked all that well and was eventually scrapped.

Chris

[ortek_service]

Originally Posted by Philips210

Back in the mid 1980s I considered building a Viewdata system using the three Mullard boards but the project didn't get off the starting blocks.
Mullard were always very obliging with technical information and never charged for it. There was a Mullard publication I received entitled" LSI Circuits for Teletext and Viewdata: The LUCY Generation" which was a very useful reference. I sadly no longer have this data and have been trying to locate a copy for a number of years. I seem to remember there was a circuit to provide random characters for testing teletext decoders.
I don't suppose anyone has a spare copy by any chance?

Regards,
Symon

Thanks for info on that publication, which I don't think I've seen / unfortunately I don't think I've got it amongst my Philips / Mullard etc. databooks collection. But if I do find it, I'll scan it to pdf.

And a quick Google doesn't seem to find it, but I have found this Philips manual on the SAA50xx IC's / use in the 'Computer Controlled Teletext Eurocct': https://heyrick.eu/software/ttx/eurocct.pdf
- which as well as mentioning the SAA5070 'LUCY', it also mentions an SAA5080 'LUCINDA' - part of the telephone line interface?. Plus also a PCF8571 telephone / ID storage device (So a EAROM / EEPROM?)

And this Philips? patent references it:
https://patentimages.storage.googlea...86001359A1.pdf
Plus a patent infringement complaint involving it? https://cases.justia.com/federal/dis...?ts=1376992993
(Interesting that there's a SPAM-Controller' on one diagram!

Also a reference to it and many other related documents, here: http://obsoletetellyemuseum.blogspot...elevision.html

[duncanlowe]

I have in the loft, an oddity of a viewdata / prestel device. A Wren. A CP/M computer in it's own right but with built in Prestel access. Supposedly portable (hardly even luggable) with an orange monochrome CRT. When it comes to it's turn to be dug out, I'll have a look what chips are in the modem, and see if it appears to be a bought in module. I believe they are rare.

[TonyDuell]

A few follow-up points.

I've dug out the older Philips viewdata set I mentioned some messages back. Inside is a stack of 3 boads, the top one contains an SAA5010 chip. This handles the signal from the little keypad-on-a-stretchy-cable which contains an SAA5000. I am pretty sure the next board downin the stack is essentially a teletext decoder using the SAA50x0 chipset but I might be wrong. Alongside those 3 boards is another PCB which is clearly the telephone line interface. More details in the future.

There are a lot of Philips databooks in the 'components archive' on bitsavers, including one that contains the datasheets for the above chipset (including the SAA5070 LUCY) Worth a look.

As for the Wren, it's a machine I would like but am unlikely to find. I suspect I have a rather rarer computer with a built-in Prestel modem, though. An HH Tiger. This contains a Z80 with 64K of RAM to run CP/M, a 6809 with 8K of RAM for I/O and a uPC7220 graphics chip with 96K of video RAM. And a Prestel modem, which IIRC doesn't use any of the normal single-chip solutions.

[Philips210]

Originally Posted by ortek_service

I have found this Philips manual on the SAA50xx IC's / use in the 'Computer Controlled Teletext Eurocct': https://heyrick.eu/software/ttx/eurocct.pdf
- which as well as mentioning the SAA5070 'LUCY', it also mentions an SAA5080 'LUCINDA' - part of the telephone line interface?. Plus also a PCF8571 telephone / ID storage device (So a EAROM / EEPROM?)

Hi ortek_service.

Thanks for the link to the Euro CCT user manual. That's very comprehensive information. This I think used the first generation CCT IC, SAA5240. A later development brought about the SAA5243 which allowed Fastext operation. That was known as Full Level One Features (FLOF). The control was often by use of a MAB8461 microcontroller.

Re the Mullard publication on Viewdata/Teletext, I recall it was an A4 sized booklet, with an orange cover. It showed a pic of a dark haired lady with some of the latest electronics. It was published in 1981. I would imagine the LUCY chip (SAA5070) must have only just been introduced.

Regards,
Symon

[alfatangowhisky]

If I may tag along with this Viewdata / Prestel thread...

Back in the 90s I had a very strange beast... a TV + Prestel / Viewdata system made by Kirby Lester (still going making pharmaceutical pill counters).

It was the size of a 1970s 'mainframe' terminal with full mechanical keyboard, colour TV with Thorn-style push-button tuner; all integrated (i.e. not separate keyboard)

I got it from a family friend in the travel agency business along with an Apple II and some other electronics they were clearing out.

It was used as my bedroom TV for many years. I remember it could make/edit Teletext pages and had hotkeys for flashing, inverse, large font text etc etc.

Particularly I remember the TV tuner could pick up the audio from analogue mobile phones of the era.

Sadly, it was swapped for a 'real' TV at one point and then became the victim of my inquisitiveness. All that survives is a photo of it in my bedroom somewhere in the family archives.

I have searched the internet high and low for information about it. Nary a picture of it anywhere and the only mention of what could be it appears in a publication: https://worldradiohistory.com/UK/Pra...ng-1979-04.pdf (p34 = p312)

Here is mentioned the 'Hermes' line of up-market colour sets and an add-on editing keyboard. Then it goes on to mention that 'intelligent terminals' are in the pipeline. Maybe this was one of them ??


If anybody out there has *anything* on these I'd be very eager to hear about it; something very vivid within my living memory that the internet has next to nothing about! Thanks!

[TonyDuell]

Back in message #22 I mentioned a couple of Philips terminals. I've got the later one working now, It's an HCS110. I've attached a few photos of the 2 logic boards, the startup menu, etc. There are more photos here :

https://www.***********/photos/tony_d...77720309574600

A couple of points for anyone trying to use one are that ctrl-CALL gets the modem setup menu and ctrl-PRINT the printer menu. Probably obvious, but...

The main processor is a Z80A with 16K of firmware, 2K battery-backed configuration RAM and 16K video RAM. Video side is based round the SAA52020 timing chain and SAA5050 character generator. No serial chip, it's bit-banged using a channel on the Z80A-CTC to generate an interrupt on the start bit of the received character.

The modem uses the TCM3101 chip (same as the Acorn BBC micro Prestel set). There's an 8048 to control the line relays and DTMF dialler chip. Line cable ends in a modern BT-type plug