Application compatibility for Windows 95 crashed a cash register

Tale from my father, who worked on Banking software in the UK in the 70's. They designed the software to allow multiple payments per day for a "rent to own" scheme for appliances. They figured a person might do two, maybe three, possibly four transactions in a day, so just in case they set the size of the "daily transaction index" to 4 bits. That's enough for 15 different payments for what's normally a single weekly payment.

Enter the alcoholic cabbie who, after every fare, would deposit the fare money so as to avoid temptation.

The quick-and-dirty solution was to pay off...