1.2 SOFTWARE CONFIGURATION
The Cray computer requires three types of software: an operating system, language systems, and applications programs. The I/O Subsystem, when present, also requires its own software. The internal features of the I/O Subsystem Software are described in the lOS Software Internal Reference Manual, CRI publication SM-0046.
1.2.1 CRAY OPERATING SYSTEM (COS)
The Cray Operating System (COS) consists of memory resident and mass storage resident programs that
• Manage resources,
• Supervise job processing, and
• Perform input/output operations.
COS also contains a set of disk resident utility programs. The operating system is activated through a system startup operation performed from a Maintenance Control Unit (MCU), which can be an I/O Subsystem. A job can consist of a compilation or assembly of a program written in some source language such as FORTRAN, followed by execution of the program resulting from the compilation or assembly.
COS consists of the following modules that execute on the mainframe central processing unit(s) (CPUs) (figure 1-1):
Executive (EXEC)
System Task Processor (STP)
Control Statement Processor (CSP) Utility programs (not shown)
EXEC (described in section 2) runs in monitor mode and is responsible for control of the system. It schedules STP tasks, manages exchange
packages, performs I/O, and handles all interrupts. EXEC has access to all of memory.
STP (described in section 3) runs in object program (user) mode. It accesses all memory other than that occupied by EXEC and is responsible for processing all user requests. STP is composed of a number of
programs known as tasks, each of which has its own exchange package.
The Control Statement Processor (CSP), described in section 20, is responsible for interpreting all job control statements and for either
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performing the requested function or making the appropriate system request. An installation option specifies whether an image of CSP resides after the STP area in memory or whether it resides on disk. In either case, it is copied into a user field for execution.
Utility programs (described in the COS Product Set Internal Reference Manual, publication SM-004l) include the loader (LOR), a library generation program (BUILD), a source language maintenance program
(UPDATE), permanent dataset utility programs, copy and positioning routines, and so on.
CSP Jobs
STP EXEC
Figure 1-1. Elements of CRAY-OS
Images of utility programs are resident on disk storage and are summoned through control statements for loading and execution in the user field.
1.2.2 LANGUAGE SYSTEMS
Currently, five language systems developed by Cray Research, Inc., are provided for the Cray Computer System. They are the FORTRAN compiler
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(CFT), the Cray Assembly Language program (CAL), the Pascal compiler, the SKOL macro translator, and A Programming Macro Language (APML) for theI/O Subsystem.
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SOF'lWARE CONFIGURATION INTRODUCTION
FORTRAN compiler
Developed in parallel with the Cray Computer System, the Cray Research, Inc., FORTRAN compiler is designed to take advantage of the vector capability of the various computers.
The compiler itself determines the need for vectorizing and generates code accordingly, removing such considerations from the programmer.
Optimizing routines examine FORTRAN source code to see if it can be vectorized. The compiler conforms with ANSI FORTRAN 77 standards.
A description of the design of the compiler is outside the scope of this publication, but is included in the Cray FORTRAN (CFT) Internal Reference Manual, publication SM-OOI7.
CAL assembler
The CAL assembler provides users with a means of expressing all hardware functions of the CPU symbolically. Augmenting the instruction repertoire is a set of versatile pseudo instructions that provides users with
options for generating macro instructions, organizing programs, and so on. Programs written in CAL may take advantage of Cray Research-provided system macros that facilitate communication with the operating system.
CAL enables the user to tailor programs to the architecture of the Cray computers. Much of the operating system as well as other software provided by Cray Research, Inc., is coded in CAL.
A description of the design of the CAL assembler is beyond the scope of this publication. See the CAL Assembler Version 1 Reference Manual, CRI publication SR-OOOO, for assembler information.
Pascal compiler
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The Cray Research, Inc., Pascal compiler supports the InternationalStandards Organization (ISO) Version 1 Pascal standard. Cray Pascal also includes extensions to the ISO standard. The compiler optionally issues messages identifying these extensions to help transport a program to a machine running a different implementation of the language.
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The Pascal Reference Manual, CRI publication SR-0060, describes the language and notes all Cray Research, Inc., extensions. The Pascal Internal Reference Manual, CRI publication SM-006l, describes the design of the compiler.
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APML assembler
The APML assembler executes on the mainframe CPU and generates absolute code that is executable in the Cray I/O Processors. APML allows the system programmer to express symbolically all hardware functions of a Cray I/O Processor. It is used to generate the I/O Subsystem software.
APML has a full range of symbolic instructions, which allow the APML user to fully use the I/O Processors arithmetic and I/O instructions,
registers, and memory. In addition, APML provides a number of macro, conditional assembly, and pseudo instructions that simplify the task of creating assembly language programs.
APML is described in the APML Reference Manual, CRI publication SM-0036.
SKOL macro translator
SKOL, a high-level programming language that stresses readability and extensibility, offers the user a well structured language while retaining the power and efficiency of the CFT compiler. SKOL is translated into FORTRAN code by a set of string-processing macro instructions. By adding to these instructions, the user can extend the language to suit
individual needs. By inserting macros directly into the SKOL source program, the programmer can define changes in the language for a specific run.
SKOL is described in the SKOL Reference Manual, CRI publication SR-0033.
1.2.3 LIBRARY ROUTINES
Cray software includes a group of subprograms that are callable from user
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programs. These subprograms reside in the $FTLIB, $PSCLIB, $SYSLIB,$ARLIB, $IOLIB, $UTLIB, and $SCILIB libraries. They are grouped by UPDATE deck name within each library. The subprograms are divided among the libraries on a functional basis.
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1.2.4 APPLICATIONS PROGRAMS
Applications programs are specialized programs usually written in a
source language such as FORTRAN to solve particular user problems. These programs are generally written by customers and are not described in this publication.
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