Jump to user comments
The representation of a computer program which is actually
read and interpreted by the computer. A program in machine
code consists of a sequence of machine instructions (possibly
interspersed with data). Instructions are binary strings
which may be either all the same size (e.g. one 32-bit word for
in which case the size of the instruction is determined from
transputer). The collection of all possible instructions
Execution of machine code may either be
hard-wired into the
microcode. The basic execution cycle consists of fetching
the next instruction from main memory, decoding it
(determining which operation it specifies and the location of
any arguments) and executing it by opening various
gates
(e.g. to allow data to flow from main memory into a CPU
the
ALU to perform an addition).
Humans almost never write programs directly in machine code.
Instead, they use a programming language which is translated
by the computer into machine code. The simplest kind of
a one-to-one correspondence with the resulting machine code
instructions but allows the use of
mnemonics (ASCII strings)
for the "
op codes" (the part of the instruction which
encodes the basic type of operation to perform) and names for
locations in the program (branch labels) and for variables and
constants.
(1995-02-15)