Unitra MK 450 is a slightly modified version of Unitra MK 250 Tape Recorder, targeted specifically as a storage for computers. The front label says “pamięć magnetofonowa”, which means “tape storage memory”. It has an extra LED indicator (signal strength?) and a switch between audio and computer modes, but otherwise it looks the same as model 250.
Tape mechanism is documented as part of Unitra MK 250 Tape Recorder.