Introduction
Preview
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.
Objective
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.
Methodology
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.