Hi, welcome to amiga.org. The cable on the SCSI unit would have to connect to a SCSI interface on the A1200 - you can't connect it to the parallel port, even though it might fit.
The A1200 doesn't come with SCSI as standard (anly the A3000 and A4000T have that)
For the A1200 you can buy a PCMCIA SCSI interface called the "Squirrel", or you can get a SCSI addon for the Phase 5 "Blizzard" range of accellerator cards. Certain "Apollo" accellerator cards also have a SCSI option.
I can't see the picture but if the SCSI unit came with the A1200 when you bought it, then the A1200 may have a SCSI interface already fitted.
