What are the disadvantages of the fourth generation computers?

Answer 1

To understand the disadvantages, you must first understand what defines a 4th generation computer. This is defined by what a computer uses as the basis for its logic circuitry:

1st generation: vacuum tubes

2nd generation: transistors and diodes

3rd generation: integrated circuits

4th generation: microprocessors

We've been using microprocessors for mainstream computing since the 1970s and are beginning to reach the limits of what can be achieved. Throughout the 4 generations the goal has been to cram more and more logic circuits into a single processor. However we're already close to the limit as the laws of thermodynamics cannot be ignored. We've already seen a shift toward dual and quad core processing and that seems likely to continue for some time to come. It's not the ideal solution, but at least processing speeds are continuing to increase, and that's always going to be "a good thing".

Quantum computing is still in its infancy and is impossible to model in a binary computer. Thus any real progress in that area is held back by the current technology. We really need a quantum computer in order to design a quantum computer. Meanwhile, Artificial Intelligence, while advancing every day, is still beyond our grasp. It was thought AI would mark the 5th generation of computers, but you cannot have a 5th generation computer if, by definition, it continues to use 4th generation technology.

The Japanese Fifth Generation Computer System (FGCS) project died a death in 1992 having never achieved its goals and costing US$400 million. If anything, they took a step backwards as the Intel x86 showed us the way forward. Despite this, they are now working on the 6th generation. While their efforts are to be applauded, they are somewhat missing the point: we're still on the 4th generation!

I've no doubt we will eventually find the next generation of computer. But I cannot help wondering if the fourth generation computer is, as successful as it has been, part of the solution or part of the problem. Judging by the Japanese efforts in the late 80s, I'd say the latter. But you never know; there's a long way to go and it may yet provide the answer. Ultimately it's the best we've got.