CF I
From The Glossary of Digital Photography
Is a type of CompactFlash card that is 43 mm by 36 mm by 3.3 mm thick. They can be read in a CF II slot by means of an adapter. See CompactFlash card

ONLINE GLOSSARY OF DIGITAL PHOTOGRAPY
Is a type of CompactFlash card that is 43 mm by 36 mm by 3.3 mm thick. They can be read in a CF II slot by means of an adapter. See CompactFlash card