Interface apparatus

An interface apparatus comprising:

• a pulse generating unit which detects the change of reading target data and generates a start pulse;
• an adjusting unit which generates an adjusting signal that changes from a first signal level to a second signal level in response to said start pulse generated by said pulse generating unit;
• a register unit comprising a data holding register which fetches first reading target data synchronously with a clock that is externally supplied when said adjusting signal is at said second signal level, and holds said reading target data and outputs it as second reading target data when said adjusting signal is at said first signal level;
• and
• a driver unit which outputs said first reading target data synchronously with a reading signal that is asynchronous with said clock when said adjusting signal is at said second signal level, and outputs said second reading target data synchronously with said reading signal when said adjusting signal is at said first signal level.