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When observing output from any 162Bug command, the XON and XOFF
characters which are in effect for the terminal port may be entered to
control the output, if the XON/XOFF protocol is enabled (default). These
characters are initialized to ^S and ^Q respectively by 162Bug, but you
may change them with the PF command. In the initialized (default) mode,
operation is as follows:
^S
^Q
Disk I/O Support
The 162Bug can initiate disk input/output by communicating with
intelligent disk controller modules over the VMEbus. Disk support
facilities built into 162Bug consist of command-level disk operations, disk
I/O system calls (only via one of the TRAP #15 instructions) for use by
user programs, and defined data structures for disk parameters.
Parameters such as the address where the module is mapped and the type
and number of devices attached to the controller module are kept in tables
by the 162Bug. Default values for these parameters are assigned at power-
up and cold-start reset, but may be altered as described in the section on
default parameters, later in this chapter.
Appendix B contains a list of the controllers presently supported, as well
as a list of the default configurations for each controller.
Blocks Versus Sectors
The logical block defines the unit of information for disk devices. A disk
is viewed by the 162Bug as a storage area divided into logical blocks. By
default, the logical block size is set to 256 bytes for every block device in
the system. The block size can be changed on a per device basis with the
IOT command.
The sector defines the unit of information for the media, as viewed by the
controller. The sector size varies for different controllers, and the value for
a specific device can be displayed and changed with the IOT command.
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(wait)
Console output is halted.
(resume)
Console output is resumed.
Disk I/O Support
3-13
3
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