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→Instruction encoding: no - branches can have predication as well, such as the SuperH bf and bt instructions. |
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Most [[stack machine]]s have "[[0-operand instruction set|0-operand]]" instruction sets in which arithmetic and logical operations lack any operand specifier fields; only instructions that push operands onto the evaluation stack or that pop operands from the stack into variables have operand specifiers. The instruction set carries out most ALU actions with postfix ([[reverse Polish notation]]) operations that work only on the expression [[Stack (abstract data type)|stack]], not on data registers or arbitrary main memory cells. This can be very convenient for compiling high-level languages, because most arithmetic expressions can be easily translated into postfix notation.<ref>{{cite web|url=http://www.cs.kent.edu/~durand/CS0/Notes/Chapter05/isa.html|title=Instruction Set Architecture (ISA)|work=Introduction to Computer Science CS 0|first=Paul|last=Durand}}</ref>
====Conditional instructions====
<!-- A conditional branch that falls though may still have other effects, e.g., decrementing a count register. -->
Conditional instructions often have a predicate field—a few bits that encode the specific condition to cause an operation to be performed rather than not performed. For example, a conditional branch instruction will transfer control if the condition is true, so that execution proceeds to a different part of the program, and not transfer control if the condition is false, so that execution continues sequentially. Some instruction sets also have conditional moves, so that the move will be executed, and the data stored in the target ___location, if the condition is true, and not executed, and the target ___location not modified, if the condition is false. Similarly, IBM [[z/Architecture]] has a conditional store instruction. A few instruction sets include a predicate field in every instruction. Having predicates on instructions is called [[predication (computer architecture)|predication]], and can ''include'' conditional-branches, such as {{code|bf}} on the [[SuperH]].<ref>https://shared-ptr.com/sh_insns.html</ref>
====Number of operands====
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