Paul Corfield wrote in message . ..
On Fri, 13 Aug 2004 15:48:25 +0100, Annabel Smyth
wrote:

On Fri, 13 Aug 2004 at 13:01:57, SJCWHUK
wrote:

They
could not allow 1 day travelcards because the train operators haven't all
come over to Oyster card.

Um - I don't quite see why not, since you can use period Travelcards on
national rail, within the relevant zones. What am I missing?

this is a complex issue but I'll try to explain.

If you had one day travelcards stored on the Oyster card you need to
tell a machine to activate it on the card as there could be several
cards of different zone combinations stored on the card and a dumb
device like a reader cannot know which one you want to activate. This

As I've mentioned in another post , it doesn't have to know. The oyster logs
the max & min zones travelled in for a given date and the next date you travel
a travelcard for the appropriate zones is deducted from the the stored
cards for that previous trip. Obviously the card will have to know the max and
min zones of all the cards it has stored so someone can't travel to zone 6 on
a day when they only have zone 4 cards but given that your average oyster card
has more processing power than a 1980s home computer this isn't going to tax
its abilities much. However all LUL seem to use it for is to either store a
pair of dates for monthly/yearly cards or stored a cash value. Thats it. What
a waste of technology.

B2003