Rob's Ramblings

Sunday, 23 April 2017

End of an Era


Those of you who follow this blog, or my social media accounts, will know that I don't share too much that is personal on-line.  Some people do too much of that - I don't need to check Facebook to see what you had for breakfast, and your tweets about how you met your mates for lunch are just white noise.  So, I don't do it.

There will be exceptions, of course, and this is one.

Given it is the Easter holidays at school, we decided to grab a few days away with our little one.  We don't generally go far, so just stuck with Pontins at Prestatyn.  Monday to Friday, just a little break.

Tuesday afternoon, I get the telephone call I never wanted to get.  It was my sister, Jenny: she had picked mum up from shopping in town and took her home, and they had found my dad dead at the foot of their stairs.  He had fallen while attempting to carry a folding bookshelf back upstairs.

Obviously I dashed up there immediately - they live in Wigan - and spent the evening with Mum and Jenny, and the police!  Any unexpected death needs investigating, apparently.  His body was collected eventually, and will be dealt with by the Coroner.  I had to return to Wales, but have been in constant contact with Mum and Jenny ever since,  Obviously they are both distraught.

This put a bit of a damper on the holiday, to put it mildly.  Obviously I am going to be exceptionally busy too, helping with Mum, dealing with all the funeral, estate, paperwork and so on.  I am pretty sure all my hobbies are going on a back burner for now.  So, that's it for Retrochallenge this year...


Dad was John O'Donnell.  He was a world-renowned aeromodeller, having been involved in the hobby for over 70 years, and having held many records.  He contributed to the model press regularly and frequently with articles and model plans,  He was a keen photographer, and ran a professional photography business doing commercial and wedding photography for a time.  As a mathematician he worked in the aeronautical and chemical industries, before finding a home as a lecturer (in statistics.)  He enjoyed serious Science Fiction, and was becoming recognised as intensely knowledgeable on the subject. He was intensely organised, and pretty much everything he did is recorded and filed away neatly.  We intend to publish as much as we can.

We have created a memorial site for him at jod.org.uk - please feel free to visit.

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Friday, 14 April 2017

Retrochallenge Day 14

A little more work today.

The teletext viewer javascript currently expects to find the entire teletext service held within the html of the web page as encoded links.  This is great for a static archive, as it places very little load on the webserver.

I had created a quick bit of php that could construct the html page when loaded, which was the source of the pages I linked to last time.  This is all well and good, but does not help with the sort of interactive services I would like to use the viewdata version for.

So today's work has been adding functionality to request pages from a server, thus allowing for ever-changing pages to be served up instead.  This involved not only modifying the JavaScript, but writing a server in php to deliver the requested pages.   This also brought out some previously unnoticed limitations in my viewdataviewer class, which I was using to parse the stored data serverside.

So, the class has had some fixes added, server written, and viewer updated.  You can play with it here, although there isn't actually anything dynamic on it at the moment.  Subpages aren't quite working right yet, but most of the rest is!

(I did break the first demo, btw, in case you were reading yesterday's post today, when I fixed a "bug" in the class file, but hadn't removed the work-around in the html generator!  It's fixed, now!)




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Thursday, 13 April 2017

Retrochallenge day 13

Blimey, where are the days going...

OK. I've taken the hacked-about teletext-editor-that-acts-as-a-viewer, and split off the hacks.  Then I modified the (latest version of) the teletext editor so that it exposes a bit more of it's internals, as the viewer needs that access...

It took a bit if trial and error, but seems to work.  Code is up on github and a demo is (temporarilly) here. I added a touch of code to allow direct linking to specific pages while I was at it!

Now to look at doing the viewdata browser that I was supposed to be doing in the first place!



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Monday, 10 April 2017

Retrochallenge Day 2.. er... 8 ..er .. 10

Blimey, has it been a week already?

OK.  I've not done much coding since last time, but I have been reading code and daydreaming planning out my next move.

Now Javascript is not my strongest language.  I can read it, and modify it, but actually writing new code is a bit of a challenge.  Part of the rationale behind this task was to get myself a bit more familiar with this hideously back to front language...

The teletext browser I used is that created by Adam Dawes based on Simon Rawles (et..al.) edit.tf editor, and grabbed from Jason's captures at uniquecodeanddata.co.uk.  The modifications are to add a pile of new functions, and truncate and or redirect others.

As the original editor has moved on somewhat since this was done, it seems logical that, if I want to do more mods to it, then i should base my code on the latest version.  If I can do it in such a way that I do not need to actually modify the editor, just call it, then that would be best.   In PHP I would, assuming it was a class, extend the class in a new file and override the relevant functions.  So... How to do this in Javascript...

I tried using prototypes ... but hit the problem that the editor is written with lots of private variables and functions, which the new functions in the viewer refer to.  Using the existing editor as the viewer's prototype doesn't work because it cannot access the private variables.  Drat.

<days pass>

After spending more time than I ever expected looking at javascript objects, inheritances, etc., I have decided not to commit myself to ever having to do anything major in this language!!

Sticking with Javascript, I think the best approach at this point would, after all, be to fork edit.tf and modify it to separate out the actual display part from the editor part, that way I can provide for a viewer, indeed, different viewers...  Might even be a mod Simon would like...

Sigh.  Bloody Javascript.

The other option would be to go back to my own viewdata viewer class, which runs serverside to create the images.  I understand this, but I was hoping not to have to do this, as it makes updating the "screen" with the page number being keyed dependant on the server, rather than being local.


So, ten days in, and all I've achieved is discovering that what I thought would be a simple task is much more complicated than I thought it would be.



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Saturday, 1 April 2017

Retrochallenge: Day 1


OK. First day, and I have to do something.. .whether I can keep this up is another matter....

I had a look at the code used for browsing Jason's teletext captures.   These use a modified version of the edit.tf teletext editor (the 'viewer'), driven by an html page consisting of a mass of links!  The viewer grabs all these, displays the first one, then accepts key-presses to get the next page number, as per a teletext page.  Plus it allows up/down arrow shenanigans to skip through.

Teletext, as you should know, shares the exact same display format as Viewdata, namely 24 (or 25) lines of 40 characters of primary colour text and simple block graphics.  As control codes take up a space on the line, this makes it harder than you might think to do multicoloured images..

So, I've got a pile of dumps of teletext pages over at www.teletext.org.uk so the obvious thing to do is use one of those, see if I can use the viewer just as it is.  That way I have a starting point, and can begin to understand the code and decide on the particular direction I want to go.

I've got a php class in working-but-incomplete state that allows me to manipulate viewdata and teletext pages.  A quick bit of code to load one of the teletext archives and then spit out each page as a link took me significantly less than an hour, and only 14 lines of new code!

So...  from this,  to this.    I think that's a positive step.

Today has, however, shown up a lot of features currently missing in vv.class that I need to add in, particularly to deal with the viewdata side of things.  That is partly what the whole point of what this was for, though: to get an idea of what I need to do next!



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Thursday, 30 March 2017

Retrochallenge 2017/04

OK... after only a few years* hiding away, I've put myself in for this again.

I've set a much smaller goal this time; something I think I can achieve, instead of something I want to achieve!  This is, I think, an important difference.  I got nowhere the last two times, mostly because I was a bit too ambitious for the limited time available to me.  (I've only sort of partially achieved the "tidy the cable nest" of 2012, and never did get anywhere with the dial-up thing from 2013.)

So this year's goal:  Write something that will allow browsing a (static) viewdata database from a web browser for use with the new Wordpress-based viewdata.org.uk.  I have a browser already, but it's a bit clunky and not very easy to incorporate into anything else.  So a nice re-write is in order, whereby I can take advantage of "modern technologies" like javascript and AJAX calls, to make the effect more seamless, and I intend to "borrow" the code behind edit.tf and the teletext-browser version thereof to make things easier..

If I can do that, I might try and finish off enough of the new version of the website to actually launch it, but no promises!!


* - Four.

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Tuesday, 28 March 2017

edit.tf hashing in php

For lack of somewhere else to put it, herewith a port to PHP of the method of encoding a videotex frame into the hash value used by the absolutely excellen edit.tf.

Ok, blogger seems to be upset by quoted php... weird.  So...   Click Here !