A zip-zap machine is a portable credit card processing machine that is operated manually. This type of machine is often used for outdoor events where computerized services are not available for each vendor individually.
The zip-zap credit card processing machine operates through the merchant loading the credit card into the machine with a carbon paper receipt. As the cross-bar on the machine is moved along the length of the machine, the raised credit card numbers are printed onto the receipt.
The zip-zap machine is also nicknamed the knuckle-buster credit card machine.
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