I has two USB 3.X standard plugs, one USB C plug, two USB 2.X, an ethernet port, two hdmi ports and a power plug/headphone/speaker jack.  I did install a scsi internal 2.5 inch harddrive.  It was straightforward.  I had been looking forward to a minicomputer like this.I had no problem getting this setup.  Do be careful and install any programs on the drive you install as you do not want to load up the solid state drive with files requiring read/write access multiple times.  Reading multiple times is fine, its reading and writing from the same memory locations on a SSD that kills it prematurely.  I plan to take this on trips to use as a portable computer so we can watch the streaming shows we desire.