1. Classification of computers

2. Classification based on capacity Microcomputer. Minicomputer. Mainframe computer. Super computer.

3. Microcomputers Workstations. Servers. Clients. Terminals. PCs and PDAs.

4. Mainframe A mainframe has 1 to 16 CPU's (modern machines more) Memory ranges from 128 Mb over 8 Gigabyte on line RAM Its processing power ranges from 80 over 550 Mips Think here of banking and insurance businesses where enormous amounts of data are processed, typically (at least) millions of records, each day.

5. Supercomputers Normally special-purpose one. Only a few around the world. E.g. Cray X-MP. Used for solving complex scientific problems.

6. Minicomputers Less expensive, physically smaller and have small storage capacity than mainframe computers. Found in museums Often people calls mobile phone or PDA as minicomputers.

7. Mainframe vs Super Computer supercomputers focus on problems which are limited by calculation speed while mainframes focus on problems which are limited by Input/Output and reliability. Because of the parallelism visible to the programmer, supercomputers are often quite complicated to program and require specialized, task-specific software. In contrast, mainframes hide parallelism from the programmer. (One side effect is that even older software can benefit from adding mainframe CPUs.) Supercomputers highly use Memory or RAM and Mainframe uses HDD most. Supercomputers tend to cater to science and the military, while mainframes tend to target business and civilian government applications. Weather modeling, protein folding analysis, and digital film rendering are all tasks well suited to supercomputers. Credit card processing, bank account management, market trading, and social insurance processing are tasks well suited to mainframes. Supercomputers often run tasks that can tolerate interruption. Mainframes tend to run those functions that must run reliably, even for years of continuous service (for example, airline bookings or credit-card processing). Mainframes assiduously and thoroughly support older software alongside new software. Supercomputers tend not to have backward compatibility as a central design feature.

8. Importance of computers Large volume of data. Accuracy. Repetitiveness. Complexity. Speed. Common data.