Now, I have almost finished to write my new book and regained tome to do various things. I would like to try again to express in English what I have learned in the University.
There are three types of aspects for how to design a system LSI chip.
(1)Low cost: Such things as DRAMs or flash memories need to be so cheaper as possible. Costs of semiconductor chips mainly depend on size. Usually a 5mmx5mm chip costs 1000 yen.
It would take a year with 100 workers to design a chip with 10% smaller than a previous, but it would gain more 10 billion yen per year.
(2)Processing power: For Microprocessor “spec” would mean prosessing power, e.g. clock frequency, in Japan or possibly in America. For example, it took a year with 1000 workers to increase a frequency from 1.9GHz to 2GHz.
(3)Flexibility: a typical case for it is that of Japanese mobile phones, in which it is required at first to release new models every three months. It often occurs that an LSI factory has to start to design without any information of required specs for the new model.
In addition to those above, this year a new aspect has appeared – power saving. Although some investigators has worked for it, this aspect had not been payed attention.
It is said to be enable to reduce power consumption to 1/100 with hardware and to 1/2 with software improvement. Though software improvement has less effect, it can be started immediately.