To play the ZX81 or Timex 1000/1500 games you will need an emulator which you can download from any of the following sites.

http://zx81.zx81.free.fr/serendipity                    NEW!!! The emulator PSPZX81 v1.0.2 for the Sony PSP machine

http://www.delhez.demon.nl/                         for DOS/WINDOW

http://www.work.de/nocash/                        for DOS/WINDOW

http://www.agate.f9.co.uk/                           for Palm Pilot

http://freestuff.grok.co.uk/                          for WINDOW

http://rus.members.beeb.net/z81.html          for LINUX/UNIX

http://www.vavasour.ca/jeff/ts1000              for DOS/WINDOW

http://www.tlienhard.com/ap800.shtml         for SONY cellular phone

http://users.aol.com/autismuk/sinclair.htm for DOS/WINDOW

http://www.aptanet.org/eightyone/              for WINDOW

http://www.zx81.nl/ for ATARI and SPECTRUM

P.S. If you know of other ZX81 emulators, please let me know.