Dial Home Device

The Dial Home Device (or DHD) is used to control the stargate. Similar to a telephone dial or touch pad (although much larger), the DHD is used to specify which other stargate to connect to when opening a gate or wormhole to another location.

Luckily for those on Earth, the stargate found in Giza in the original movie was missing its DHD. A computer was programmed to act as the controling device. If there had been a DHD with that first rediscovered stargate, we probably would have run into the Goa'uld in the 1920's before we ready to handle it (barely).