Serial is a Killer
ASYNCH port ships 10 bits for 8-bit byte of data, a 20% overhead
38,400bps, 57,600bps, 115,200bps (not as fast as raw 128Kbps 2B ISDN!)
Requires 16550 or 16650 UART with FIFO buffer
PC / Windows cannot service serial port interrupts fast enough, losing data
Lowering the port speed may improve throughput performance! (check PPP stats)