User`s manual

Use of the Firmware After Use by the SBC ROM Debugger
SBCSCSI/D1 5-15
5
XMSG
structures logged- ncr_siop, siop_cns, siop_struc
description- The SCRIPTS received an extended message for the
current physically threaded command. The Firmware
copies the received message into the MESSAGE-IN buffer
and acts upon the message if it was a synchronous data
transfer request
or wide data transfer request message.
XSTO
structures logged- ncr_siop
description- The Firmware determined that the external selection time
out timer has expired. This condition is similar to an
STO. The difference is that the internal SIOP time out
timer failed to work and so the SIOP had to be reset and
reinitialized.
Use of the Firmware After Use by the SBC ROM Debugger
Special considerations are required when using the Firmware to talk to an
SCSI device after the SBC ROM Debugger (e.g., 167Bug or 187Bug) is used to
talk to that same device. ROM Debugger commands such as IOP (I/O
Physical) and BO (Boot) set and expect certain configuration modes on the
device. The ROM Debugger makes every attempt to leave the device in a state
in which it can later be used by other software such as an operating system.
Caution must be used when returning control to the ROM Debugger from the
operating system. For example, the operating system might set a device in the
synchronous data transfer mode. If control is returned to the ROM Debugger,
the ROM Debugger may not be able to access the device (using the
asynchronous mode). The solution for this case is to RESET the SCSI device
on the SCSI bus to return the device to its default state. The ROM Debugger
provides a RESET command and ENV parameters to RESET the SCSI bus. The
user must be aware of these restrictions, and other ROM Debugger to
operating system handoff considerations, when using the Firmware.