Is it permissible to buy shares in computer companies and the like? And is it permissible to contribute to companies that invest money in buying and selling shares of other companies that deal only in technological devices?

It is permissible to invest in companies, provided they do not engage in usury, sell prohibited items, or conduct business through illicit means. Otherwise, it is not permissible, as usury is forbidden by the Qur'an, Sunnah, and scholarly consensus.