Since IRAF is a large system it is undesirable to have to maintain a separate copy of IRAF for each machine architecture on a network. For this reason IRAF provides support for multiple architectures within a single copy of IRAF. To be accessible by multiple network clients, this central IRAF system will typically be NFS mounted on each client.
Multiple architecture support is implemented by separating the IRAF sources and binaries into different directory trees. The sources are architecture independent and hence sharable by machines of any architecture. All of the architecture dependence is concentrated into the binaries, which are collected together into the so-called BIN directories, one for each architecture. The BIN directory contains all the object files, object libraries, executables, and shared library images for an architecture, supporting both IRAF execution and software development for that architecture. A given system can support any number of BIN directories, and therefore any number of architectures.
In IRAF terminology, when we refer to an "architecture" what we really mean is a type of BIN. The correspondence between BINs and hardware architectures is not necessarily one-to-one, i.e., multiple BINs can exist for a single compiler architecture by compiling the system with different compilation flags, as different versions of the software, and so on. Examples of some currently supported software architectures are shown below.
Architecture System Description
generic any no binaries (default IRAF configuration) sparc Sun-4 Sun SPARC (RISC) architecture, integral fpu f68881 Sun-3 mc68020, 68881 floating point coprocessor pg Sun-4 Sun/IRAF compiled for profiling ddec Decstation DEC Fortran version of DSUX/IRAF dmip Decstation MIPS Risc Fortran version of DSUX/IRAF rs6000 IBM IBM RS/6000 running AIX irix SGI SGI IRIX, MIPS cpu f2c Macintosh A/UX, using Fortran-to-C translation and GCC
Most of these correspond to hardware architectures or floating point hardware options. The exceptions are the generic architecture, which is what the distributed system is configured to by default (to avoid having any architecture dependent binary files mingled with the sources), and the "pg" architecture, which is not normally distributed to user sites, but is a good example of a custom software architecture used for software development.
When running IRAF on a system configured for multiple architectures,
selection of the BIN (architecture) to be used is controlled by the UNIX
% setenv IRAFARCH ddecwould cause IRAF to run using the ddec architecture, corresponding to the BIN directory bin.ddec. Once inside the CL one can check the current architecture by entering one of the following commands (the output in each case is shown as well).
cl> show IRAFARCH ddecor
cl> show arch .ddec