Motorola MVME187 User Manual

Page of 173
Disk I/O Support
4-17
4
A command packet for one type of controller module usually does 
not have the same format as a command packet for a different type 
of module. The system call facilities which do disk I/O accept a 
generalized (controller-independent) packet format as an 
argument, and translate it into a controller-specific packet, which is 
then sent to the specified device. 
Refer to the system call descriptions in the Debugging Package for 
Motorola 88K RISC CPUs User's Manual
 for details on the format and 
construction of these standardized "user" packets. 
The packets which a controller module expects to be given vary 
from controller to controller. The disk driver module for the 
particular hardware module (board) must take the standardized 
packet given to a trap function and create a new packet which is 
specifically tailored for the disk drive controller it is sent to. Refer 
to documentation on the particular controller module for the 
format of its packets, and for using the IOC command. 
Default 187Bug Controller and Device Parameters
187Bug initializes the parameter tables for a default configuration 
of controllers and devices (refer to Appendix B). If the system needs 
to be configured differently than this default configuration (for 
example, to use a 70MB Winchester drive where the default is a 
40MB Winchester drive), then these tables must be changed.