What is hidden computing?

In which frequency band does Bluetooth operate and can you think of (or find) another wireless technology that uses the same frequency band?

What is a piconet and how many slaves connect to a master in such a network? (Hint: Bluetooth uses a 3-bit address field to identify the master and its slaves)

There are two types of links in Bluetooth, SCO and ACL. Which one would you use for voice traffic and which one for regular (non-voice) traffic?