Abstract and Result should be accompanied with the report in a separate paper.
and Business telephone users in Sri Lanka are not provided with a detailed
listing of outgoing telephone calls. The detailed listing is very important
owing to the fact of rising telephone call charges and in turn an additional
burden on subscriber.
using ITDL subscribers can formulate their own telephone management criteria in
order to minimize call duration and unnecessary calls. This is because the call
charges are varying depending on time a call started and the number of unit
consumed. In addition, a subscriber can locate any unauthorized calls originated
by the telephone in the absence of him or her.
has a storing capacity of around 600 telephone calls. For domestic use this is
normally the usage of two months and for office usage it is advisable to take
print outs each month and reset the system to leave room for storing more call
can easily plug in ITDL to his telephone and to main power. The system has a
very simple operating system. Further, it can run as a stand along system, even
in the absence of main power. It needs little maintenance. ITDL can be kept
alongside the telephone or else in a place, which are cool, dry and dust free.
report covers most of the design that I thought vital to be documented. It
starts with a project overview to its main components and highlights the design
approach. The subsequent sections explain the design and operational aspects in
working on the project for quit a while and achieving most of the goals, I am
pleased with the attained success and the challenges overcame in meeting the
project objectives. In this project, I was able to incorporate the Z80
microprocessor with externally built hardware and make it perform to
specification. The project provided me with a strong background for similar
tasks I might undertake in the field of microprocessor in the future. I was able
to place myself in an almost real situation of electronic product design and
implementation and learn the steps involved in such a process. Specific to my
project, I was able to prove that the idea of fetching the telephone number and
associate timing function scenario I have described in the previous sections,
are quite feasible
I learned that various problems can occur when interfacing the Z80 with a hardware setup. In my case, timing was a very critical factor. However, the Z80 can handle these time intensive applications if provided with a suitable external hardware.
Full circuit diagram of the the ITDL which was drawn using Visio professional.
The above diagram can be opened on Visio environment. then copy it to the page 22 which is not included in the site http://www.mvps.org/visio/3rdparty.htm
PCB layout was drawn using Expresspcb ver 2.6.2 You can download the software free of charge at
The PCB layout can be opened on ExpressPCB environment. then copy it to the page 23 which is not included in the site
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