Juan A. Gonzalez
Paper #3
ATM Machine Model
An ATM machine is used today to reduce the number of people visiting the bank.
Automating common and repetitive tasks reduces traffic inside a bank branch. The three main
tasks an ATM allows the user to do is, withdraw money, deposit money, and check balance. I
think an ATM machine works the following way: it has a connection to the bank to check the
unique ID found on the card and the PIN entered by the user. It then shows menus for the user
to allow him/her to accomplish his/her desired task. If the user wants to check the balance, it
checks the balance with a secure database the bank has and shows it to the user. If he/she
wants to withdraw the machine checks if their balance is equal or greater than the amount
entered by the user, if it is greater or equal the machine has a dispensing mechanism that
counts the money and dispenses it to the customer. If she/he wants to deposit, it puts the
amount entered as a pending until it is verified by the bank.
I am allowed to withdraw $300 dollars per day at an ATM, if I need more cash I need to
go in to the bank. If I withdraw my limit and then go to another machine and try to withdraw
more money, that machine would check with a database to see if my I have reached my
allowed cash withdraw limit, then would present an error saying I cannot withdraw anymore.
My card contains a unique ID indentifying my bank, and bank account number. This information
is used to pinpoint the right user and then verify his PIN (personal identification number). If the
wrong PIN is entered then no access is granted to the account. There are pauses in between the
steps of a transaction to simplify the process and not confuse the customer. The pauses are
short. If you type ahead during the pauses the inputs are not recognized. The card is read in the
machine to extract the bank information and the account information. The card does not have
to stay inside the machine. There are some ATM machines that allow you to slide your card
only. I always count my money because the machine could have made a mistake.
I asked Austin Williamson and James Warren the same questions, their responses varied
a little. They both described a connection to the bank to verify the account and PIN; James
mentioned a secured network. Austin does not uses an ATM machine do he did not know his
limit, James said his withdraw limit is $500 dollars per day. James said another ATM would not
give you the money if you had reached the withdrawal limit because it checks if you have
reached your withdrawal limit; Austin said it would give you the money and charge you a fee.
Austin said that the card contains the account number; James said the card contained a
magnetic strip with the card number. Austin said this information would determine the account
and verify the PIN entered by the user; James said the information is sent over the network to
be verified. If the wrong PIN is entered Austin said it would tell you so and James said it would
give you a second try. Austin said there are pauses in between steps to prevent other programs
to hack into the ATM machine; James said to verify along the way and make sure nothing goes
wrong. Austin did not know how long the pauses were since he does not use an ATM machine;
James said they were about three seconds. Austin answered that the input is ignored if you
enter information ahead; James said he has never tried that. Austin said that the magnetic strip
is read when the card is inserted; James said it gets locked in the machine. Austin said that it
was locked in there because the user is still accessing his account, for security reasons; James
mentioned safety reasons as well. They both count their money to make sure no mistakes were
made.
I got somewhat the same answers from the two people I asked. James emphasized on
security and Austin had never used an ATM machine, but their answers were very similar. Both
of the people I asked the questions to are science majors and know how systems work,
therefore I would say both of them had a good mental model of how an ATM machine works.
For a technology savvy I think it’s easy to understand somewhat how an ATM machine works
but for the regular people I think it would be harder. They did not mention any interface
features being problematic, and I think this is because an ATM machine really limits the paths
the user can take, by only allowing certain inputs. I believe ATM machines have been upgraded
many times and there are not many improvements that can be done, once we get into
fingerprint recognition and eye recognition then we might see some big changes in the ATM
once again. Until then I think the ATM is in well shape and works fairly well.