The following attributes characterize systems programming: • The
programmer can make assumptions about the hardware and other properties of the system that the program runs on, and will often exploit those properties, for example by using an
algorithm that is known to be efficient when used with specific hardware. • Usually a
low-level programming language or programming language dialect is used so that: • Programs can operate in resource-constrained environments • Programs can be efficient with little
runtime overhead, possibly having either a small
runtime library or none at all • Programs may use direct and "raw" control over memory access and
control flow • The programmer may write parts of the program directly in
assembly language • Often systems programs cannot be run in a
debugger. Running the program in a
simulated environment can sometimes be used to reduce this problem. In systems programming, often limited programming facilities are available. The use of
automatic garbage collection is not common and
debugging is sometimes hard to do. The
runtime library, if available at all, is usually far less powerful, and does less error checking. Because of those limitations,
monitoring and
logging are often used;
operating systems may have extremely elaborate logging subsystems. Implementing certain parts in
operating systems and networking requires systems programming, for example implementing paging (
virtual memory) or a
device driver for an operating system. == History ==