Outboard formatting

Outboard formatting is a technique for reducing the amount of line traffic between the host processor and an attached subsystem. The reduction is achieved by sending only variable data across the network. This data is combined with constant data, such as a physical map, by a program within the subsystem. The formatted data can then be displayed.

You can use outboard formatting with a 3650 Host Communication Logical Unit, an 8100 Series processor with DPPX and DPS Version 2, or a terminal attached through a 3174 control unit. Maps used by the 3650 must be redefined using the 3650 transformation definition language before they can be used. Maps to be used with the 8100 must be generated on the 8100 using either an SDF II utility or the interactive map definition component of the DPS Version 2.

If a program in the host processor sends a lot of mapped data to subsystems, you can reduce line traffic by telling BMS to transmit only the variable data in maps. The subsystem must then perform the mapping operation when it receives the data. BMS prefixes the variable data with information that identifies the subsystem map to be used to format the data.

Terminals that support outboard formatting have OBFORMAT(YES) in their TYPETERM definition. When a program issues a SEND MAP command for such a terminal, and the specified map definition contains OBFMT=YES, BMS assumes that the subsystem is going to format the data and generates an appropriate data stream. If you send a map that has OBFMT=YES to a terminal that does not support outboard formatting, BMS ignores the OBFMT operand.

See Using batch data interchange for more information about programming some of the devices that support outboard formatting.