I/O interfaces are published regularly in this magazine. Yet, each and every of them has its own special properties which makes it almost unique. The 8-bit port described in this article provides eight buffered outputs, eight inputs at TTL level, and communicates with the PC via the popular I2C interface. In spite of all these facilities, the circuit has been kept surprisingly compact.Using an I2C interface has a number of important advantages: all communications take place via a 2-wire arrangement; the interface is reliable, fairly fast, and well documented; and many I/O components are obtainable at reasonable prices. The only drawback is that the control computer or microcontroller needs an I2C interface. Over the past few years, several I2C interfaces have been published in this magazine: the latest one in this year’s March issue. That interface was intended for connection to the printer port. It is supported by DDLs that may be used in a Windows environment. Great attention has also been paid to its use in microcontroller systems.