I recently bought this frame from a gentleman who bought a closed bike shop and builds and sells bikes from his 10 or more sheds full of parts. He teaches his church youth kids to build them as a way of staying out of trouble, I love that. I acquired 90% of the parts I would need to put a bike together. He was 100% sure this frame is a Cannondale frame (maybe 1987), but there is no serial number or marks at all that we can see. The fork reads Tange TF-R.
I managed to find a couple of similar frames on web search that suggest the 1987 Vintage Cannodale identification could be correct. The really unique way the top-tube intersects the downtube before the head tube makes me think this is a very small frame. I would suggest it's a 1987 SR600 in 48cm