LH's U1SF9M-BK or U1PP25F-BK offers user the ability to connect a serial device and a
  parallel device simultaneously. The U1S2P-9M-25F-BK only require one USB port for connection
  of two devices, therefore free up your other USB port for more connection. The serial port
  provides data transfer speed up to 115 Kbps and the parallel port gives you 2.7 MB/sec speed.
  The adapter is versatile that you can use it on desktop or laptop.
   
 
  Compatible with USB 2.0 and 1.1
     
  Supports wake-on-line & power management function
   
  No IRQ, DMA, I/O Address resources required
   
  Dual data buffers for upstream and downstream data flow
   
  Hot swappable
      
  Easy plug & play
   
  Serial high speed transfer up to 115 Kbps
   
  Parallel port support SPP mode
   
  Parallel transfer speed up to 2.7 MB/sec
   
  Supports DB9 Windows/Mac/Linux O.S..,DB25F Only Supports Windows
   
  U1S2P-9M-25F-BK