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The project was first conceived along the lines of a goal that is simple to understand and yet a challenge to implement. Other factors, which influenced the choice of the project, include the application of the Z80 microprocessor. Further, it enabled me to apply the knowledge gained through the Engineering Council Examination and the skills acquired during the eight years I have worked in the field of Electronic Engineering.





The project goal is to store and print the telephone number, the time the call originated and the duration of each call on a monthly basis for subscriber telephones.




The project design was carried out in two phases. Phase I involved in the design of the ITDL and PCB. For this a wide variety of telephone products and associated literature were thoroughly studied. Most importantly, the data sheets of communication ICs collected from respective semiconductor manufacturers and further invited them for their suggestion for the improvement of the project. First all the individual events were modularized to form the complete design and layout the basic architecture of ITDL. Then each module was tested in account of its performance and was linked to successive event and was tested again for overall performance. Once this breadboard design part was accomplished, PCB design and other electrical connections together with its associated accessories were accompanied. In conclusion, the first phase took 90% of the complete project cost and time (approximately 8 months).  


The phase II of the project was to write Z80 assembly instruction for ITDL. The written programs were checked manually with test data and assembled into machine code by a Z80 assembler. A universal programmer wrote these machine instructions into EPROMs of ITDL.     



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Last modified: July 13, 2002