playdium play cards?

[colin886]

hi last time i went to playdium i was confused by how the bar code on the playcard could hold numbers and be changed.
If anyone knows how to make something like the playcard readers that can be programed to add,take,and tell the total number of credits on the card by swiping the card through the reader
and how to make the card that holds the "credits"/in memory
please post scematic
any help is very much appreciated

ps on the back of the play card it looks like

-------------------------------------------
| 9945 0331 1829 6544 |
| |
| |||||||||||||||||||||||||||||||| |
| | | | | | || | | | \ | \ \| |
-------------------------------------------
the |||||| is the barcode and the numbers are numbers

The bar code and the numbers aren't correct
:!: :!: :!: :!:

 

[colin886]

or a small device that contains a memory chip that holds numbers
on press button number goes down an amount
when another button pressed add an amount
when attached to to a device with 3 7 segment diplay shows number that is on memmory

 

[evandude]

the barcode doesn't store the number of credits. the barcode just identifies who you are, and then they look you up in their database and see how many credits you have. if the barcode stored the number of credits, it would have to change every time you added or used credits.

it's kind of like a credit card... your card doesn't store any info about how much money you have, (if it did, people would quickly figure out how to hack them and give themselves more money) it just provides a reference to your account so they know who to charge things to...

 

[colin886]

Thanks