Use the DEVTYPE macro instruction to request information relating to the characteristics of an I/O device and to cause this information to be placed into a specified area. (The results of a DEVTYPE macro instruction executed before a checkpoint is taken should not be considered valid after a checkpoint/restart occurs.) The IHADVA macro maps the data returned by the DEVTYPE macro - see IHADVA Mapping macro.

The topics that follow discuss the DEVTYPE macro, device characteristics, and the output for specific devices.

Your program can issue the DEVTYPE macro while executing in 24- or 31-bit mode. If your program is executing in 31-bit mode, the parameter list, information list, and the UCB address list can reside above the 16 MB line.

Table 4 shows the output for each device type that results from issuing the DEVTYPE macro without the INFOLIST parameter.

For all currently supported devices, DEVTYPE does not return enough information to perform space calculations. TRKCALC should be used to perform space calculations. For information on using the TRKCALC macro, see Performing Track Calculations (TRKCALC macro).