TAL Programmer's Guide

Glossary
096254 Tandem Computers Incorporated Glossary–11
REAL(64). A data type that requires a quadrupleword of storage and that can represent
a 64-bit floating-point number.
recursion. The ability of a procedure or subprocedure to call itself.
redefinition. A declaration, within a structure, that associates a new identifier and
sometimes a new description with a previously declared item in the same structure.
reduced instruction set computing. See “RISC.”
reference parameter. An argument for which a calling procedure (or subprocedure)
passes an address to a called procedure (or subprocedure). The called procedure or
subprocedure can modify the original argument in the caller’s scope. Contrast with
“value parameter.”
referral structure. A declaration that allocates storage for a structure whose layout is the
same as the layout of a specified structure or structure pointer. Contrast with
“definition structure” and “template structure.”
register. A facility that stores information about a running process. Registers include
the program register, the instruction register, the local register, the stack register, the
register stack, and the environment register.
register stack. A facility that contains the registers R0 through R7 for arithmetic
operations, of which R5, R6, and R7 also serve as index registers.
register pointer (RP). An indicator that points to the top of the register stack.
relational operator. A signed (<, =, >, <=, >= <>) or unsigned ('<', '=', '>', '<=', '>=', '<>')
operator that performs signed or unsigned comparison, respectively, of two operands
and then returns a true or false state.
relocatable data. A global data block that Binder can relocate during the binding
session.
RESIDENT procedure. A procedure you declare using the RESIDENT keyword; a
procedure that remains in main memory for the duration of program execution. The
operating system does not swap pages of RESIDENT code.
RETURN statement. A statement that returns control from a procedure or a
subprocedure to the caller. From functions, the RETURN statement can return a value.
As of the D20 release, RETURN can also return a condition-code value.
RISC. Reduced instruction set computing. A processor architecture based on a
relatively small and simple instruction set, a large number of general-purpose
registers, and an optimized instruction pipeline that supports high-performance
instruction execution. Contrast with “CISC.”
RP. Register pointer. An indicator that points to the top of the register stack.
RSCAN statement. A statement that scans sequential bytes, right to left, for a test
character.
RTLDECS. A file, provided by the CRE, that contains external declarations for CRELIB
functions whose names begin with RTL_. See also “CRELIB.”