as shown in fig7 a a data input block 97 comprises a keyboard 201 a communication port 51 with rs232c and a floppy disk controller 202 also a hard disk unit 203 is provided separately a first processing block 1 is mainly consisted of a first processor 4 a second processing block 98 contains a second processor 7 which is a cpu arranged for shift to and back from the energy saving mode upon stopping and feeding of a clock signal respectively and is coupled to a bus line 210 also a rom 204 for start action a second memory 9 of dram and a backup ram 205 which is an sram for storage of individual data of returning from the resume mode are coupled to the bus line 210 both ends of the bus line 210 are connected to the first processor 4 and a display block 99 respectively the display block 99 has a graphic controller 206 and a liquid crystal controller driver 207 arranged in a display circuit there are also provided a video ram 209 and a liquid crystal display 208 for energy saving operation corresponding components only in the arrangement are activated while the remaining components are de energized this energy saving technique is illustrated in more detail in table 1 in.