A RF (radio frequency) card has circuits, memories and even a microprocessor like a chip card,
but it doesn’t have a contact disc and replace it with an antenna to exchange data with the reader.
It doesn’t have scratch and dirt problems like magnetic card or IC card. There are 2 kinds of RF cards:
Low Frequency: Operating frequency is about 125 KHz. They are usually used in an ID or access applications.

High Frequency: Operating frequency is about 13.56 MHz. ISO 14443 (contactless card or proximity card) & ISO 15693 (vicinity card) are two open standards for it. We usually use it in a fast access or fast payment applications.

TTL, UART, RS232, USB (HID or I/O direct control)

Human Interface Device, it is a USB device defined by Microsoft. The device’s firmware and driver have to follow
the standards of USB.org and Microsoft’s USB HID class. To install a HID device on a Windows system
(Windows 98 SE, ME, 2000, XP, 2003 server) is an easy job. Not like most devices installation,
it needs no manufacturer’s driver because windows systems have HID driver built inside.
Most USB keyboard, mouse, joystick are HID devices.

Personal Computer/ Smart Card standard, it is a group of smart card manufacturers (http://www.pcscworkgroup.com/).
They define smart cards’ and card readers’ hardware and software specifications, and Microsoft implemented
it into a set of Win32 API. The following picture is its architecture and specification sections:

The advantage is that the application software won’t be affected by the replacement of card readers, like most software in Windows systems. The disadvantage is that the standard lacks the flexibility to add customized functions like reading / writing magnetic cards, memory cards, SAM cards or I/O controls.

ID: ID, access control, member cards

Prepaid: phone cards, cards for rental devices (copy machines, wash machines)

Payment: credit cards, bank cards