Abstractions

Advances in programming (and computers) come not from connecting things, but from separating them.

In the early days of computing (the 1950s and 1960s), hardware, processors, and software were tied together. The early processors had instructions that assumed the presence of tape drives. Assemblers knew about specific hardware devices. EBCDIC was based on the rows available on punch cards.

Abstractions allow for the decoupling of system components. Not detachment, since we need components connected to exchange information, but decoupled so that a component can be replaced by another.

The COBOL and FORTRAN languages offered a degree of separation from the processor. While FORTRAN I was closely tied to IBM hardware (being little more than a high-powered macro assembler) later versions of FORTRAN delivered on machine-independent code.

The C language showed than a language could be truly portable across multiple hardware platforms, by abstracting the programming constructs to a common set. 

Unix abstracted the file system. It isolated the details of files and directories and provided a common interface to them, regardless of the device. Everything in Unix (and by inheritance, Linux) is a file or a directory. Or if you prefer, everything is a stream.

Microsoft Windows abstracted the graphics and printing (and later, networking) for PC applications.

The Java JVM and the .NET CLR decouple execution from the processor. Java offers "write once, run anywhere" and has done a good job of delivering on that promise. Microsoft focusses more on "write in any language and run on .NET" which has served them well.

Virtualization separates processes from real hardware. Today's virtualization environments provide the same processor as the underlying real hardware -- Intel Pentium on Intel Pentium, for example. I expect that future virtualization environments will offer cross-processor emulation, the equivalent of a 6800 on a Z-80, or an Alpha chip on an Intel Pentium. Once that happens, I expect a new, completely virtual processor to emerge. (In a sense, it already has in the form of the Java JVM and .NET ILM languages.)

Cloud computing offers another form of abstraction, separating processes from underlying hardware.

Each of these abstractions allowed people to become more productive. By decoupling system components, abstraction lets us focus on a smaller space of the problem and lets us ignore other parts of the problem. If the abstracted bits are well-known and not part of the core problem, abstraction helps by eliminating work. (If the abstraction isolates part of the core problem, then it doesn't help because we will still be worrying about the abstracted bits.)