BBC Schedula: Difference between revisions

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(Correct pentium spelling, add subsections, add naming.)
(Add Alan's schedula screen shot and some sat decoder guff)
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This system had at it's heart a specially programmed BBC Microcomputer, which controlled the station's audio and video hardware whenever live programs were not being shown, so that the network was kept busy.
This system had at it's heart a specially programmed BBC Microcomputer, which controlled the station's audio and video hardware whenever live programs were not being shown, so that the network was kept busy.


First created around 1994, by [[Dominic Plunkett]] and [[Alan Murrell]]. Dominic worked out how to drive YSTV's satellite receiver by analysing the bit pattern emitted from the remote control, and transcribed this into the BBCs memory (this was quite a feat as the BBC does not have much memory). However, he never let slip as to how he worked out it was actually on.  
First created in 1994, by [[Dominic Plunkett]] and [[Alan Murrell]]. Dominic worked out how to drive YSTV's satellite receiver by analysing the bit pattern emitted from the remote control, and transcribed this into the BBCs memory to be later replayed as though coming from the remote itself. During 1994-95 it was let loose to the masses, and [[Chris Kwouk]] stepped forward as a keen exponent as he knew it was the answer to many of YSTV's scheduling problems.  


During 1994-95 it was let loose to the masses, and [[Chris Kwouk]] stepped forward as a keen exponent as he knew it was the answer to many of YSTV's scheduling problems. However, some people were slightly baffled by user interface. During a visit to [[Alan Murrell]] sometime later in 1995 [[Owain Davies]] discussed the issue of the user interface with Alan and suggested he could write an alternate but he could never match the excellent work that had been done in device control. Alan offered to substitute the user interface for a serial interface thus allowing another computer to control the BBC schedula.  
[[Image:AlansScheduler.png|left|thumb|160px|An intractable user interface]]
However, some people were slightly baffled by user interface. During a visit to [[Alan Murrell]] sometime later in 1995 [[Owain Davies]] discussed the issue of the user interface with Alan and suggested he could write an alternate but he could never match the excellent work that had been done in device control. Alan offered to substitute the user interface for a serial interface thus allowing another computer to control the BBC schedula.  


==BBC Micro and DOS front end==
==BBC Micro and DOS front end==
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The abbreviation spread to the next monitor along which showed the output of the terrestrial tuners, logically shortened to 'Tuna A' 'Tuna B' and 'Tuna C' certainly by 1997.
The abbreviation spread to the next monitor along which showed the output of the terrestrial tuners, logically shortened to 'Tuna A' 'Tuna B' and 'Tuna C' certainly by 1997.
==Satellites supported==
The satellite channel changer has had 4 incarnations:
* the original [[Dominic Plunkett]] version for the {{unsure|unbranded}} decoder which was replaced when a new larger dish was installed to resolve picture interference
* a Grundig GSR1/MkII which later failed in an electrical storm
* a Grundig GRD150 decoder which later became obsolete when Sky switched to digital broadcasting
* a Pace Sky Digibox
They all work on the same principle, study the remote control codes on an oscilloscope, translate these into timings which are stored in the schedula ROM for later playback. The last 3 versions included some logic gates glued to the circuit board of the satellite decoder to mix the input from the remote (which still worked) with the computer control. In Dominic's version he simply wire-OR'd the computer into the circuit board for a slightly simpler solution.


==End of BBC Micro era==
==End of BBC Micro era==
In a final burst of enthusiasm in early 2005, [[Dave Baker]] and [[Richard Ash]] moved the database to the main YSTV server and the PHP control daemon to the [[Video Server]] so that the FreeBSD machine could be retired, mainly in the interests of it's space in the rack. Over the summer of 2005, the whole lot was replaced by [[Spider and SchedSeven]], a new from-scratch solution built by [[Rob Humphrey]] and [[Dave Baker]].
In a final burst of enthusiasm in early 2005, [[Dave Baker]] and [[Richard Ash]] moved the database to the main YSTV server and the PHP control daemon to the [[Video Server]] so that the FreeBSD machine could be retired, mainly in the interests of it's space in the rack. Over the summer of 2005, the whole lot was replaced by [[Spider and SchedSeven]], a new from-scratch solution built by [[Rob Humphrey]] and [[Dave Baker]].

Revision as of 17:46, 19 May 2007

BBC as in BBC Microcomputer, not BBC as in BBC broadcasts, although for much of it's history most of the content controlled was rebroadcasts of mainstream TV.

BBC Micro system

This system had at it's heart a specially programmed BBC Microcomputer, which controlled the station's audio and video hardware whenever live programs were not being shown, so that the network was kept busy.

First created in 1994, by Dominic Plunkett and Alan Murrell. Dominic worked out how to drive YSTV's satellite receiver by analysing the bit pattern emitted from the remote control, and transcribed this into the BBCs memory to be later replayed as though coming from the remote itself. During 1994-95 it was let loose to the masses, and Chris Kwouk stepped forward as a keen exponent as he knew it was the answer to many of YSTV's scheduling problems.

An intractable user interface

However, some people were slightly baffled by user interface. During a visit to Alan Murrell sometime later in 1995 Owain Davies discussed the issue of the user interface with Alan and suggested he could write an alternate but he could never match the excellent work that had been done in device control. Alan offered to substitute the user interface for a serial interface thus allowing another computer to control the BBC schedula.

BBC Micro and DOS front end

Owain set about writing a user interface based in C on a DOS platform. The program would need to run from a boot disk disk on a hard disk less 386. He thought he would try and use pointers to store all of the scheduling information. This version soon found itself in the bin after many crashes and he reverted to a static array. The resulting system looked a little like a personal planner on a sky box today. True to his word, Alan, produced the ammended program for the BBC. First trial, did not go successful at first, until Alan advised to lift the front edge up of the BBC up a couple of centimetres and then drop it. After which, much to Owain's delight, it worked. The new system proved popular and was used during 1995-96.

At the start of 1996-97, Owain attempted a further feat with the PC user interface. He had experimented with an extremely crude VGA to composite converter from Bull Electrical, that somehow seemed to work. His aim was to get the scheduler to announce the start of a program and show schedules by putting it's VGA output to network and showing some graphics. It was trialed before it was ready, and the system would get itself into a very confused state. Reluctantly, he reverted to the previous version.

Rob Sprowson came along a little while later and further improved it, including re-doing the remote control code to control a Sky digibox rather than the original analogue receiver, and hooking it up to the Station Video Mux

BBC Micro and PHP system

The serial input to the system proved to be invaluable towards the end of the system's life, by which time no-one really knew how the innards worked. It enabled Kevin BowmanUnverified or incomplete information to create a webpage/database based system to replace the DOS front-end. This was initially a stand-alone system that sat in the control room running on a Pentium running FreeBSD. Everything was written in PHP - even the daemon that read the database and kicked out the requests to the BBC over the serial port. This required a specially re-compiled version of PHP that allowed the script to keep running for ever rather than being killed after accumulating 10 seconds of CPU time (usually some weeks after being set running).

Dave Baker then moved the front end pages to the YSTV web server, still driving the same machine for the back-end. This meant that the Scheduling Manager could fill up the schedules without actually coming in to the station. At about the same time some more hacks were inserted to make the system talk to the Video Server, at least after a fashion. Throughout this the BBC had to be kept, as no-one knew what protocol passed between it at the Network Audio Mux and Station Video Mux doing the actual control.

Origin of the name

It's uncertainUnverified or incomplete information where the abbreviation of 'schedula' rather than 'scheduler' came from. The original Alan Murrell system ROMs were titled 'YSTV Scheduler ROM' and 'YSTV Hardware Control ROM' respectively, though the top-row-of-the-monitor-rack monitor which showed the scheduler's output was labelled with a stash of free business cards from "Diane's Hair Salon" which weren't large enough for the full name.

The abbreviation spread to the next monitor along which showed the output of the terrestrial tuners, logically shortened to 'Tuna A' 'Tuna B' and 'Tuna C' certainly by 1997.

Satellites supported

The satellite channel changer has had 4 incarnations:

  • the original Dominic Plunkett version for the unbrandedUnverified or incomplete information decoder which was replaced when a new larger dish was installed to resolve picture interference
  • a Grundig GSR1/MkII which later failed in an electrical storm
  • a Grundig GRD150 decoder which later became obsolete when Sky switched to digital broadcasting
  • a Pace Sky Digibox

They all work on the same principle, study the remote control codes on an oscilloscope, translate these into timings which are stored in the schedula ROM for later playback. The last 3 versions included some logic gates glued to the circuit board of the satellite decoder to mix the input from the remote (which still worked) with the computer control. In Dominic's version he simply wire-OR'd the computer into the circuit board for a slightly simpler solution.

End of BBC Micro era

In a final burst of enthusiasm in early 2005, Dave Baker and Richard Ash moved the database to the main YSTV server and the PHP control daemon to the Video Server so that the FreeBSD machine could be retired, mainly in the interests of it's space in the rack. Over the summer of 2005, the whole lot was replaced by Spider and SchedSeven, a new from-scratch solution built by Rob Humphrey and Dave Baker.