I would suggest a system composed of the following parts:

1: The MASTER station. This would contain a card reader used to set a token
on a card. It would also serve as the database repository, and would drive
an RS485 or similar link to the SLAVE stations to poll for card insertions.
This device would need some form of mass storage, so it could be anything
from a PIC with a bunch of external flash memory to a full-blown PC. Again,
I would use some form of hashtable to store the data, designing it to level
wear on the flash (if flash was used).

2: One or more SLAVE stations, each associated with one snack dispenser.
These would be a simple processor that reads the card, responds to polls and
commands from the MASTER, sends a dispense command to the dispenser, and
lights LEDs or an LCD to indicate things like: 'RETRY CARD',  'NO SNACK
PROGRAMMED', 'EXPIRED',  'DISPENSIING', etc


----- Original Message -----
From: "Kresho" <piclist@ADVANCEDTECHNIKA.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, April 22, 2004 12:02 AM
Subject: Re: [PIC:] Sorting through millions of numbers


> > How many total cards will you system have to handle? I expect this is
far
> > less than the possible 10 million.
>
> There are up to 10million different card numbers but i can't ever see this
> many cards being used. So, for an example, lets say that one person uses
the
> card every 10 seconds (even that is unlikey) = 8640 cards in a day. Lets
> also say that the redemption time is 14 days. Thats 14x8640 = 120960 cards
> that could pass through in that time.
>
> > Are you concerned about forged cards?
>
> Nope!
>
> > Do only certain members get a snack token? How are they determined?
>
> That's up to management. All i told them is they have to swipe the card
> (during a setup or recharge mode) to activate a token.
>
> > Are the cards read-only or do they some read-write capability you can
use?
>
> Read only.
>
> > How many redemption stations will be needed?
>
> Not sure as yet, but it may be more than 1. If it's more than 1 then i
would
> have a single "database board" with all the card usage info and seperate
> boards at each machine. The machines would send the card number to the
> database board and get the token via some sort of connection yet to be
> determined, probably a simple multidrop rs485 thing.
>
> > How many transactions per day do you anticipate?
>
> Who knows? I'm taking 1 per 10 seconds as a worst case senario.
>
> Rgds,
>
> Kresho Sprem
>
> > -----Original Message-----
> > From: pic microcontroller discussion list
> > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Bob Ammerman
> > Sent: Thursday, 22 April 2004 1:28 PM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: Re: [PIC:] Sorting through millions of numbers
> >
> >
> > Ok, lets go back to the basics of the problem:
> >
>
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