The Hardware Software Interface

One of my Computer Science professors recently lent me the book Computer Organization and Design: The Hardware/Software Design Interface written by two pioneers in the field of computer hardware: David Patterson and John Hennessy. This book is an excellent book about how the computers machinery is actually designed and built written by the people who introduced to the world RISC and MIPS. The book is widely used in undergraduate courses on computer and quite rightly so. I’ve only made my way through the first two chapters, but I already feel that this book deserves a place alongside the classics of computer science.

The reason I’m reading the book is because I’m interested in the hardware aspect of computers just as much as the software side. With so many powerful high-level languages that keep the programmer many layers of abstraction away from the hardware, it’s easy to forget that the computer will only reveal its full power if you learn how it works and learn it well. While it is certainly important to have a strong understanding of how the mathematics of computing work, it is equally important to know how to take those mathematics and concepts (some of which are incredibly powerful) and translate them to patterns of ones and zero. MIT’s Structure and Implementation of Computer Programs is probably the best book ever to be written for the purpose of teaching the fundamentals of pure computer science, covering everything from simple abstractions to machine-code generation. It’s not really a book to read unless what you want is a deep understanding of how computers compute. Combine that with a book like Computer Organization and Design (perhaps its graduate level partner) and you have a combination that if well utilized gives you a very complete understanding of computer systems.

Bridging the Hardware Software Interface is a very special piece of software : the compiler. The compiler is what will take your high-level mathematically abstract program and translate it to the bare bytes and the computer with deal with. You can’t implement a half-decent compiler without understanding well both the computer’s hardware architecture as well as the range of abstractions that you want to implement on that architecture. Steve Yegge correctly argues that you haven’t fully understood computers unless you have understood compilers. Compilers tie together all the fundamental concepts of computer science: programming languages, algorithms, data structures and of course, the hardware software interface. Unfortunately compilers are often glossed over during a computer science education. There has been this break in computer technology education with computer science gradually moving towards a focus on pure software with the bare minimum of hardware and electrical engineering dealing with hardware with a minimum of software (mostly assembly and C). Personally, I think this is a grave mistake, one that leads to a gradual lowering in the quality of computer scientists.

What is the solution? The ideal would be a overhaul of the computer science curriculum, perhaps merging many aspects of computer science and electrical engineering, bridging the hardware-software interface by a proper emphasis on both. However this would also mean that students would have to study a lot more, the curriculum would become quite a good deal harder and there would have to be a move away from having so-called “industry standard” languages such as Java as the main teaching medium. Ideally all computer science courses would have both Computer Organization and Design and SICP as textbooks at some point during the course of the degree. As you can well imagine, this isn’t going to happen any time soon, probably never. I’m going to be studying both of them because I love computers and would never pass up a chance to learn more about them, but I am acutely aware that most of my classmates do not share my enthusiasm.

But what can I do, as a lone college freshman to gain a complete understanding of computer systems, the power they have to offer, the challenges they involve and the many interesting facets of the hardware-software interface? Luckily, I don’t have to bound by the college curriculum (and neither does anyone else). Both of the books I have talked about are written with students in mind (albeit dedicated and determined students) and should be easily available. In fact SICP can be downloaded as PDF or read online for free. The software tools that both of these books use are also freely available online. There are also a number of videos available online of courses conducted by the authors of SICP and I feel that they are an excellent companion to the book. And if that isn’t enough, there is always the World Wide Web, with a plethora of information sites and freely available tools as well many projects to which to contribute to put one’s knowledge to work. Learning should be a proactive activity with just as much enthusiasm shown by the student as the teacher. As the Zen saying goes: “When the student is ready, the teacher shall appear”. This could not be more true in the information age.

Happy Learning !!

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