Blackberry maker RIM is adding its name to the list of challengers to Apple’s iPad.

The company is expected to launch a touchscreen tablet computer in November, which will work closely with the Blackberry smartphone ecosystem and which will be called a BlackPad, according to a report by Bloomberg News.

The device will be of similar size to the iPad, which has sold over 3.3 million units since launching in April. Costing around 500 dollars the Blackpad will feature a 22-centimetre screen and access the Internet via both Wi-Fi and cellular connections, the report said.

Dell is launching its own mini-tablet, The Streak, in the U.S. by the end of the month. On Thursday, Microsoft chief executive Steve Ballmer said the company is also working on tablet PC technology, though he gave no timeline for launch.

Also entering the fray is HP, the world’s largest PC maker, which will launch a tablet based on the WebOS operating system it acquired when it bought Palm earlier this year.

Samsung and LG have already announced the launch of tablet computers running Google’s Android operating system later this year, while Motorola is also expected to release an Android tablet in November.