You are given the task to design the link level functions of a new general
purpose modem. The analog and lowest-level digital functions already exist
- at least on paper - and the link level functions may be built upon the
existing functions rawsend(length,buf) and rawrec(length,buf) that just
send and receive bytes without paying attention to framing, error control
etc. Consider the advantages and disadvantages of the HDLC frame structure
for this purpose.
Solution