Icom radios do not use the C4FM digital mode , which is a proprietary system from Yaesu. Icom's digital system is called D-STAR, and Icom radios are designed to be compatible with D-STAR, not C4FM.
yaesu page on FT857D For the manual you can Google ft-857d manual
ft-857d manual
program-cable-yaesu-ft
borrowed cable uses pl2303 - check this again as might be cp2102 downloading_cp210x windows-8-prolific-driver-not-working
