Hardware Reference
In-Depth Information
FIGURE A.12 Categories of instruction operators and examples of each . All computers
generally provide a full set of operations for the first three categories. The support for system
functions in the instruction set varies widely among architectures, but all computers must have
some instruction support for basic system functions. The amount of support in the instruction
set for the last four categories may vary from none to an extensive set of special instructions.
Floating-point instructions will be provided in any computer that is intended for use in an ap-
plication that makes much use of floating point. These instructions are sometimes part of an
optional instruction set. Decimal and string instructions are sometimes primitives, as in the
VAX or the IBM 360, or may be synthesized by the compiler from simpler instructions. Graph-
ics instructions typically operate on many smaller data items in parallel—for example, per-
forming eight 8-bit additions on two 64-bit operands.
 
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