The environment in which HCD operates

HCD is part of z/OS. It needs a running z/OS system before it can be used to define a hardware configuration. Therefore, an installation should first load a z/OS system, using an old IODF, or a ServerPac Starter IODF to IPL the z/OS system for the first time. HCD can then be used on that system to define the full configuration.

HCD uses the unit information modules (UIMs) of z/OS. UIMs contain device dependent information, such as parameters and features of devices. The UIMs must be installed in the z/OS system before you use HCD to define a configuration. The UIMs are also used at IPL time to build the UCBs. That is why they have to be installed in SYS1.NUCLEUS at IPL time.

UIMs are provided for the IBM devices supported by z/OS, OS/390, or MVS by the device product owners. You can write your own UIMs for non-IBM devices. To get information about UIMs, see z/OS MVS Device Validation Supportz/OS MVS Device Validation Support.