Programming from scratch [closed]

Answer 1

There's a great textbook called The Elements of Computing Systems: Building a Modern Computer from First Principles by Noam Nisan and Shimon Schocken, which serves as the basis for a university course taught by the authors called Workshop In Computer Construction - From NAND to Tetris in 12 Steps. This course is also taught at other universities under different names.

There's a 10 minute introduction on YouTube and a 1 hour Google TechTalk on Google Video, both by the author himself.

The official companion web site is http://nand2tetris.org/

Don't let the title "Computer Construction" fool you. By "computer", the author does not just mean the rectangular plastic box on your desk, he means the entire computing system, from the individual logic gates up to highest-level application programming.

The book/course teaches you

• how to create your own individual logic gates
• how to build your own logic circuits
• how to build your own CPU
• how to program in machine code directly
• how to program in your own assembler (which you wrote in machine code)
• how to write your own virtual machine
• how to design, implement and program in your own high-level language (which you wrote in assembler)
• how to write a bootloader
• how to write an operating system
• and ultimately how to write a simple game

Answer 2

Beginning at the basics is 1 and 0. You need to know what instructions your processor supports and what registers and cache, etc. exist. Then it would be handy to write a little assembler compiler in machine code (for readable 1 and 0). If you have that, you can write the first real compiler for a simple higher language, and so on (each built using a lower-level "language"). You should know, though, that creating a simple operating system can take years of planning and even more time to develop, debug, etc. (and all this before you can even think of seeing something useful on the screen). And that operating system won't be able to run on any other processor than yours. Then you need drivers, etc for every single bit of hardware. And there are many steps to go from here. Beginning at the level of 1 and 0 is not very rewarding, since you won't see anything of it for a very long time. Simply don't.

Answer 3

Most C compilers can emit code that's not designed to run in the context of an OS (see the memtest86+ codebase for example), but that's going to severely limit the feature set provided by any of those compilers. (In particular, you're not going to get anything like malloc).

Answer 4

AFAIK, nothing you are describing exists in modern computers. Nowadays, you will always encounter layers of operating systems, bootstrapping, and possibly even virtualization between you and the hardware.

If you really want to understand the deep secrets of programming and how applications run on the hardware, I suggest you take an operating systems course or read up on how they work. For instance, the Andy Tanenbaum book Operating Systems Design and Implementation may be the ticket.

Answer 5

If you want to get down to the hardware, try checking out microcontrollers like PIC and AVR. I recently had the chance to work with some of those platforms, where the code you write (in C or assembler) actually runs on bare metal.

Of course, that only means that you have to implement some core OS services yourself, like interrupt routines to handle input. Much of it is available as example code, but still small enough to read and understand the whole system.

As far as computer archaeology goes, try taking the basic courses in digital circuits, computer architecture and compiler technology at you nearest university. That satisfied my curiosity, as well as my need to write programs with raw binary opcodes :-)

Answer 6

I suggest you get yourself a small microcontroller system to play around with. TI has a small system-on-a-usbstick based on the MSP430 for $20. You do not need a compiler or an OS to run code on this system. In fact, with only 128 bytes of ram it would be a challenge to get an OS onto it.

If you really want to start from scratch, you the write down your program in assembly code on a piece of paper and translate it by hand to machine code. Then you type in the machine code in a hex editor to get your ones and zeroes. This is really taking it to the extreme and you will not learn anything from doing the machine code by hand. Writing a program in assembly code will teach you a lot, though.

You do need a tool to get your program into flash memory for the cpu to be able to execute it, but once the flash has been programmed, there are no tools, os or anything like that involved.