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Debugger General Information
B
Disk I/O via 177Bug Commands
IOI (Input/Output Inquiry)
IOP (Physical I/O to Disk)
B-16
The device probe mechanism utilizes the SCSI commands
ÒInquiryÓ and ÒMode SenseÓ. If the specified controller is non-SCSI,
the probe simply returns a status of Òdevice present and unknownÓ.
The device probe makes an entry into the device descriptor table
with the pertinent data. After an entry has been made, the next time
a probe is done it simply returns with Òdevice presentÓ status
(pointer to the device descriptor).
The 177Bug commands listed in the following paragraphs are
provided for disk I/O. Detailed instructions for their use are found
in the Debugging Package for Motorola 68K CISC CPUs User's Manual.
When a command is issued to a particular controller LUN and
device LUN, these LUNs are remembered by 177Bug so that the
next disk command defaults to use the same controller and device.
This command probes the system for all possible CLUN/DLUN
combinations and displays inquiry data for devices which support
it. The device descriptor table has space for a maximum of 16 device
descriptors. Use the IOI command to view the table or clear it if
necessary.
IOP allows you to:
Read blocks of data
Write blocks of data
Format a specified device in a certain way
IOP creates a command packet from the arguments you have
specified, then invokes the proper system call function to carry out
the operation.
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