Memory device and operating method of the memory device and host device

A memory device, and an operating method of the memory device and a host device are provided. The method of operating a memory device includes receiving a command for requesting an Eye Open Monitor (EOM) operation performance from a host device, receiving pattern data including data and non-data from the host device, performing the EOM operation which performs an error count to correspond to the data, and does not perform the error count on the non-data, and transmitting an EOM response signal including the error count result to the host device.