Disk I/O Support
Default 197Bug Controller and Device Parameters
197Bug 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.
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There are three ways to change the parameter tables:
❏Using BO or BH. When the user invokes one of these commands, the configuration area of the disk is read and the parameters corresponding to that device are rewritten according to the parameter information contained in the configuration area. This is a temporary change. If a cold- start reset occurs, then the default parameter information is written back into the tables.
❏Using IOT. The user can use this command to manually reconfigure the parameter table for any controller and/or device that is different from the default. This is also a temporary change and is overwritten if a
❏Obtain the source. The user may change the configuration files and rebuild 197Bug so that it has different defaults. Changes made to the defaults are permanent until changed again.
Disk I/O Error Codes
197Bug returns an error code if an attempted disk operation is unsuccessful.
Network I/O Support
The Network Boot Firmware provides the capability to boot the CPU through the ROM debugger using a network (local Ethernet interface) as the boot device.
The booting process is executed in two distinct phases.
❏The first phase allows the diskless remote node to discover its network identity and the name of the file to be booted.
❏The second phase has the diskless remote node reading the boot file across the network into its memory.
The various modules (capabilities) and the dependencies of these modules that support the overall network boot function are described in the following paragraphs.
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