On July 5, Greece will hold a referendum to decide their financial future. After amassing massive debt after the financial crisis, the country has been taking loans from the European Commission, the European Central Bank, and the International Monetary Fund. These entities have imposed strict austerity measures that have hampered growth, and the vote on Sunday will decide whether Greece will continue to play by the lenders' rules or if they will go against them, leading to a likely debt default and a possible expulsion from the euro.

In the meantime, the Greek financial stability council has issued a withdrawal limit of €60 per day on ATMs across the country to prevent panicked citizens from bleeding the banks dry (foreigners are exempt from these limits). But how does a country just all of a sudden put a cork in thousands upon thousands of ATMs? The short answer, is they don't.

“As far as how ATMs work, and how ATM networks work, individual operators control their network and the software that runs on it," says Jeffrey Dudash of NCR, a U.S.-based ATM manufacturer. No individual government official can press a button to set a country-wide withdrawal limit, they can only make the decision and enforce compliance however possible.

“There are some ATM systems that will be able to run on software and distribute software from a central location," Dudash says, but those are controlled by the ATM owners and operators. "Sometimes on older ATMs it has to be done on a case by case basis where a technician will have to go out to a location and manually load the software onto it.” Meaning there were probably some busy ATM technicians across Greece this week.

And what if an ATM operator decides they want to secretly keep their machines pumping freely, unbound by any governmental restrictions? “I can’t speak to that,” says Dudash. €60 it is.