IMOGen Test Card & Teletext Generator

[pichacker]

Jeff,

I did actually get the prog up and running, just before symantic shut it for me, and it did indeed look good. I'm guessing that there is a signature in the code that symantic is being over zelous with and mistaking it for something that it may not be.

Keep up the good work...

Steve.

[Parabola]

What Jeffrey is referring to is that the earlier versions didn't contain the Microsoft version info resource (the fields you see when you view the properties of an executable through right clicking on it) whose absence tends to upset some virus scanners (Avast, for one). However, I have now added the resource in v1.07.

I've never had a threat warning reported for this app before, other than because of the anomoly mentioned above. I have downloaded the version posted online, verified it hasn't been modified from my master and have run it through two anti virus scanners, AVG and Avast, which both report no threat found.

I would suggest that you are receiving a false positive based on Symantec's heuristic analysis of the file contents. It's written in BBC Basic for Windows and this is not an unknown occurrance with BB4W apps and some aniti virus programs.

Of course, the ultimate decision is always going to be yours

[dragonser]

Originally Posted by Parabola

Assuming it's not beyond the mathematical restraints of the coding regime, then producing differing standards is the function of the various rag-bag collection of software apps that I've written, or hacked, and use to create suitable PROM images for my hardware (all written in BB4W, Dave)

What is the standard you have in mind?

Hi,
many thanks for the explanation, it helps to know
that the changes could be implemented if there was sufficient demand.
One standard that I have seen mentioned here is 405 line NTSC but I know that that is probably quite an obscure one.
regards Peter

[Parabola]

405 is an interesting standard to generate at 12MHz, but that's probably a different thread altogether

405 Line NTSC is certainly possible.

I've just completed, though so far not tested, a new version of firmware (VHDL) that, along with a revised PROM layout, allows a total of 18 (yes, 18!) Teletext pages to be produced by the same hardware, without losing any of the previous functionality. This has taken many attempts and incarnations of the code, as it really didn't want to fit into the available 64 macrocells! Fingers crossed it works out....

[Tazman1966]

I look forward to getting together and seeing the results

[Parabola]

Hello Tas,

Well it's looking promising. Firmware version 2.3MT (MT = MaxText) has passed the first real word operational test.

I manually created a 'new format' single frame 625 mono PROM, including 3 text pages, and installed it into one of the spare production units. Then updated that unit to the latest firmware. On hooking it up to a TV the Test Card image was generated fine, and all 3 text pages could be selected...so looking good

I now need to create an 8 field / 4 PROM PAL colour set, including 12 text pages (3 per PROM) and test that to ensure that the subcarrier phasing is maintained throughout all the addressing manouvres. Should be fine, I think

Then I need to re-write the PROM creation app so it builds PROM images in the new format.

When I've got it sorted I'll give you a shout and we can upgrade your unit. It now seems a little futile to have asked you to select four pages from the available catalogue, when now you can have all of them!

[Parabola]

There has been some mention previously in this thread, and in some others in the past, in fact it appears to be a popular misconception, that Richard Russell’s Test Card Generator is no longer available to buy. I have been in touch with Richard today and he assures me that this is not the case.

The Turkish company linked to on Richard’s page here are still willing and able to supply units to the UK. I know at the moment the linked webpage seems to be just a blank white page, and it has been reported previously, here as one example, that they don’t always respond to emails. Therefore it may be worthwhile contacting Richard directly if you do want one and experience any communication problems.

All of which kind of makes the rationale for developing IMOGen any further, or indeed at all in the first place, rather questionable and I shall put an end to my witterings about it at this point.

Mods: Now may be a good time to close this thread as I think as it’s pretty much run it’s course. Thanks.

[Andy Green]

Originally Posted by Parabola

... All of which kind of makes the rationale for developing IMOGen any further, or indeed at all in the first place, rather questionable and I shall put an end to my witterings about it at this point.

I wouldn't agree. It's always fascinating to see this sort of development work described on the forum.

I have an RT Russell test card gen, for many years now, and it is a great piece of kit, but it is a few years old now. (I also have to Auroras, the 1st Gen multi standard and a later single standard model)

The ability to hold 16 pages of text is a great improvement, and I for one would be interested in one for this reason alone.

Alos as RS232 serial ports become scarcer, a USB interface (or even an IP) would be very beneficial!

How about publishing the board layout, providing the eprom images and
allowing others to build thir own units, if you don't want the trouble and expense of selling completed units or kits?

Certainly you shouldn't consider your work as a waste of time in any way!

Andy EI3HG

[Parabola]

I don't think any of it is/was a waste of time. I just thought it best this thread faded away asap, as it contains certain incorrect statements about the non-availablility of Richard Russell's generator.

[terrykc]

Originally Posted by Parabola

As mentioned previously, I've re-coded a selection of original Teletext pages for use with IMOGen - currently 16 in all.

There is also a small, self-contained Windows viewer application that allows them to be viewed on a PC for selection purposes prior to programming.

If anyone would like to take a trip down the Teletext memory lane themselves, then this application can be download from here -

http://www.vintagepixels.co.uk/imoge...View_v1-07.zip

Just extract the two files contained in the zip file to a new folder - double click on the executable to run it, then load Demo.car from the "File" menu. The upper menu bar navigation options will then become active and are fairly self-explanatory.

Hope you enjoy the nostalgia!

I would like to enjoy the nostalgia!

Unfortunately, the files are no longer available.

Any chance of making them available again?

[terrykc]

This talk of Teletext test pages brings back memories of designing test pages for the Stock Exchange TOPIC (Teletext Output Price Information Computer) system over 30 years ago!

The only editing terminal available on the development system was intended for use on the BT Viewdata system and only handled (and displayed!) the features of the original system, so I used my crib sheet of escape sequences to enter 'new' facilities like double height and background colour - and hoped that when I saw the result on my prototype decoder that all would be well!

My repertoire included a crosshatch and pages for checking/setting purity, etc., so that the maintenance staff didn't need to cart test equipment around the streets of the City of London ...

[Parabola]

Hello again,

As this thread is still open, and the final development work mentioned in post #26 is now complete, I thought I would just add a final update to conclude the story.

Just to recap. The new firmware and PROM layout allows 3 pages of text per frame (PROM). So, for an 8 field (4 frame) 4 PROM PAL colour test card 12 pages of text are possible, and for a 2 field (single frame) 1 PROM monochrome test card 3 pages are possible. This means that for a unit configured with all 625 test cards the total text pages held can be a maximum of 18. If the unit is configured to include a 405 test card, and thus only two 625 test cards, the maximum available text pages drops to 15.

The total available pages are divided up into separate magazines. The 12 pages available when the colour test card is selected are in the 1xx (100,101,102 etc) range, with the remaining two mono test card selections having pages in the 2xx and 3xx ranges respectively. This is necessary to avoid confusion to the poor old teletext decoder when switching between test card selections. If this is not done, then the situation can arise that if you manage to switch between test cards (and thus text magazines) between fields within a frame, it is possible to end up with the top half of one page and the bottom half of another – most disconcerting! A well defined numbering system prevents this.

As it’s time to wrap this saga up, I really should publicly thank a few people (Oscar-esque speech coming!)

Firstly, to Richard Russell, whose own TCGEN was a huge inspiration for this project, and whose BB4Win made is possible for a numpty like me to be able to create software applications powerful enough to create and manipulate PROM data how I needed it.

Secondly, to Jeffrey Borinsky, for finally pushing me down the CPLD route, and away from CMOS/TTL – it was key to this design getting to the point it has. Also, for his patience dealing with my daft questions whilst trying to get to grips with VHDL, digital PAL coding, and the black art of DAC reconstruction filters.

Finally, to my beta testers and fellow TV hoarders, you know who you are, who have provided feedback, support and encouragement through the darker times when it all seemed to be too much effort.

Thank you, all

So, to finish up, a whole sequence of pictures (if I get them all uploaded) showing an all 625 configured unit doing it's stuff through a 26” 1979 Philips G11 with Teletext and Viewdata decoders, touch tuning and ultrasonic remote.

All moiré patterns and strange colour rendition (orange reds!) are down to the camera, sorry.

The first set of pictures show –

1) The set-up – IMOGen --> Modulator --> G11
2) 625 PAL Colour Test card, TCF
3) 625 Mono Test Card 1, TCC (625 version)
4) 625 Mono Test Card 2, TCD (not accurate for 625, but for input to an Aurora)

More to follow…..

[Parabola]

Teletext Pages 100 - 104

[Parabola]

Teletext Pages 105-109

[Parabola]

Teletext Pages 110 - 111 and 200 - 202

[Parabola]

And finally, Teletext Pages 300 - 302

That's all folks

[Brian R Pateman]

Excellent results!

It's nice to see them displayed on a top class television too.

(Now you see why we don't routinely close threads at the OP's request).

[terrykc]

Absolutely fantastic!

One observation - I would have preferred a more optimistic weather forecast ...

This reminds me of a Philips pattern generator we had in the late 80s which generated a teletext test page using only one line per field!

I can't remember anything about the test page - except that I thought it was rubbish! So, I took the test page from our Viewdata system, modified it slightly, and replaced the PROM image in the generator.

I recalled a bit of the Broadcast Teletext Specification which, as far as I know, anybody has ever used, which says that rows can be transmitted in any order.

As rows 11 and 12 of my page contained ENGINEERING TEST PAGE in double height, I started with that, followed by rows 13, 10,14,9,15,8 etc.

With the page spread over 24 frames, the appearance was reminiscent of a faster version of the well known Thames TV ident ...

[Tazman1966]

An excellent piece of kit that I can vouch for having one of the first
I look forward to the update when I can get myself and the unit round to your place.

Thanks again.

[Parabola]

Originally Posted by Brian R Pateman

It's nice to see them displayed on a top class television too.

Yes, it is certainly a very grand set and the sole reason I needed a Teletext Generator at all, as it's the only vintage Teletext set I have. A Viewdata generator (probably just as a software app) with connection via modem is is the next task.

Originally Posted by terrykc

Absolutely fantastic!

One observation - I would have preferred a more optimistic weather forecast ...

Thanks. Sorry about the weather outlook. It took me about 6 hours to re-code that page back into 7 bit ascii from a .gif of the original and, to be honest, the actual forecast wasn't the highest priority in my mind

Originally Posted by terrykc

This reminds me of a Philips pattern generator we had in the late 80s which generated a teletext test page using only one line per field!...

IMOGen puts out 12 lines per field, so the page counter between page selections moves like a blur! I was a little concerned at first as to whether so many lines would be tolerated by such an early decoder as is in the G11, but it deals with it without issue.

IMOGen now uses 6 separate switchable VBIs per frame/PROM, which is 72 stored data lines. These separate VBIs are 'paged' in and out in a sequence controlled by the CPLD. Sequencing VBIs within individal PROMs and across multiple PROM sets was quite a challenge with a mere 64 macrocell CPLD - I ended up using 63 of the available macrocells in the end, although it was the whole 64 in one version. Creating the PROM images to maintain correct page numbering and subcarrier/burst phase throughout all this sequencing and paging also took some work.

Originally Posted by terrykc

I recalled a bit of the Broadcast Teletext Specification which, as far as I know, anybody has ever used, which says that rows can be transmitted in any order.

Well yes, as long as you keep a track of where your header rows are inserted. One out of sequence data line on the wrong side of a header row and it all goes to pot!

Originally Posted by Tazman1966

I look forward to the update when I can get myself and the unit round to your place.

Yep, I'll sort that out asap. I've got some new, different, buttons on order too