at least, more network bandwidth is used up to pull the "raw data" to the client machine for processing back into a standard format. On the client end, DAL was originally accessed directly through a system extension (named simply "DAL" in System 7), but it was later rolled into a single ODBC-like driver layer, the Data Access Manager (DAM). DAM was ODBC-like in concept, but did not include the SQL layers, it was strictly a system for sending "opaque" queries and receiving result sets. DAM also included the concept of a "query document" that allowed the DAL (or other) queries to be written in an authoring system and then easily used in any client application. Servers and clients One of the more common clients for DAM was HyperCard. The combination of HyperCard and DAL presented a serious challenge to existing vendors who could offer nothing with a GUI. Apple gave a series of demos of HyperCard/DAL, and soon Oracle Corporation purchased a HyperCard-clone, PLUS from Spinnaker Software, to produce Oracle Card. For much of the 1990s a direct-DAL database server was available on the Macintosh, Butler SQL. However, like any server software on the "classic" Mac OS, Butler was seriously hampered by the Mac's single-user file system and limited multitasking and could never really deliver the sort of performance the same server would have on Windows NT or Unix. The PrimeBase division of German software developer SNAP Innovation GmbH continues to support DAL in their cross platform SQL database server (originally known as P.INK SQL). Their extended version of DAL is called PrimeBaseTalk (PBT) and is fully backward compatible with DAL. Their architecture does not include Data Access Manager and the resulting performance gains are considerable. References Macintosh operating systems development Classic Mac OS programming tools