Most technical reports (TRs) are written in PostScript and compressed with the UNIX compress utility giving them a .Z extension.
They may be easily uncompressed on UNIX with the command 'uncompress'.
On Windows machines, you may use the WinZip utility which is freely available.
After uncompressing, you will have a .ps file, which is a PostScript file. You can print it on any PostScript compatible printer, or view it with Ghostview or GSview depending on whether you are using a UNIX or Windows machine, respectively.