SAS/SHARE User's Guide

Host Differences

Access is said to be cross-architecture when the client session and the server session are running on machines that have different internal representations of data. Differences in internal representation of data can arise because of hardware differences between two machines. For example, IBM mainframe machines represent floating-point numbers differently than computers that are based on Intel CPUs, which represent them differently than Digital VAX computers. The codes for internal representation of character data also vary; EBCDIC and ASCII are two major character-encoding systems.

Different operating systems and C-language compilers also cause differences in representation. Differences are due to different alignment requirements of aggregate data types, such as the inter-element padding in a particular C structure. Also, two compilers for the same type of CPU may implement simple data types with differing lengths.

It may not always be obvious when the cross-architecture features of SAS/SHARE software are required. OS/390 to CMS access is not cross-architecture because the underlying representation of data in the two operating systems is the same. On the other hand, sharing data between OpenVMS for VAX and OpenVMS for AXP does constitute cross-architecture access because data are represented differently on the Digital VAX and Alpha AXP architectures, even when the same operating system is used. For complete details about architectural compatibility, see Identical Architectural Groups.

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