Computer engineering deals with the design of computers and computer systems. Computer terminals were used for time sharing access to central computers. Computer viruses infect a variety of different subsystems on their host computers and software. The Apple I computer differed from the other kit-style hobby computers of era. Users communicated using systems developed for specific mainframe computers. Free readers are available for all kinds of desktop computers and many PDAs. Servers offer (or host) various services to other network computers and users. Their passion was for building computers and software, not entertainment. There are several systems for encoding the Polish alphabet for computers. Babbage's machines were among the first mechanical computers. They are different from binary digital electronic computers based on transistors. Numerous small digital computers were also used. These were soon combined with the emerging technology of digital computers. The company was also strong in semiconductor technology, including integrated circuits used in computers. He is extremely skilled in technology, especially computers and games.