1747-L553控制模塊，A-B產品尺寸
網絡自動引導是187Bug中包含的一個軟件例程提供啟動操作系統機制的EPROM使用網絡（本地以太網接口）作為引導設備的系統。
網絡引導順序1.Network Auto Boot例程自動掃描控制器和設備按指定順序運行，直到找到包含引導媒體的可引導設備或列表為筋疲力盡的
1747-L553控制模塊2起動。控制器掃描順序從最低開始檢測到的控制器邏輯單元號（LUN）檢測到最高的LUN。（有關違約，請參閱附錄CLUN。）3.通電時，啟用網絡引導，并提供遇到的驅動器號和控制器號有效系統控制臺上顯示以下消息：“正在進行網絡引導…要中止hit<BREAK>”在此消息之后，有一個允許您中止的延遲如果您愿意，請參閱網絡引導過程。獲得控制權在沒有網絡引導的情況下，您可以按斷開鍵或軟件中止或重置開關。
4.然后實際輸入/輸出開始：程序指向將指定介質的卷ID加載到RAM中，然后控制傳遞給它。
網絡自動引導由中包含的參數控制NIOT和ENV命令。這些參數允許選擇并允許編程啟動延遲。請參閱附錄A中的ENV命令。
重新啟動系統您可以使用三種不同的方式將系統初始化為已知狀態方法：重置、中止和中斷。每一個都有使在某些情況下，它比其他方法更合適。調試器具有可在事件中使用的特殊功能您的設置/操作參數已損壞或不符合健全性檢查。此功能：? 通過按下
同時，在中止之前釋放重置開關轉換? 指示187Bug使用默認設置/操作ROM中的參數，而不是您的設置/操作NVRAM中的參數。
ROM默認值請參閱ENV命令（附錄A）。
Network Auto Boot is a software routine contained in the 187Bug
EPROMs that provides a mechanism for booting an operating
system using a network (local Ethernet interface) as the boot device.
Network Boot Sequence
1. The Network Auto Boot routine automatically scans for
controllers and devices in a specified sequence until a valid
bootable device containing a boot media is found or the list is
exhausted.
2. If a valid bootable device is found, a boot from that device is
started.
The controller scanning sequence goes from the lowest
controller Logical Unit Number (LUN) detected to the
highest LUN detected. (Refer to Appendix C for default
LUNs.) 3. At powerup, Network Boot is enabled, and providing the
drive and controller numbers encountered are valid, the
following message is displayed on the system console:
"Network Boot in progress... To abort hit <BREAK>"
Following this message there is a delay to allow you to abort
the Network Boot process if you wish. To gain control
without Network Boot, you can press the BREAK key or the
software ABORT or RESET switches.
4. Then the actual I/O begins: the program pointed to within
the volume ID of the media specified is loaded into RAM and
control passed to it.
Network Auto Boot is controlled by parameters contained in the
NIOT and ENV commands. These parameters allow the selection
of specific boot devices, systems, and files, and allow programming
of the Boot delay. Refer to the ENV command in Appendix A.
Restarting the System
You can initialize the system to a known state in three different
ways: reset, abort, and break. Each has characteristics which make
it more appropriate than the others in certain situations.
The debugger has a special feature which can be used in the event
your setup/operation parameters are corrupted or do not meet a
sanity check. This feature:
? Is activated by pressing the RESET and ABORT switches at the
same time, and releasing the RESET switch before the ABORT
switch.
? Instructs 187Bug to use the default setup/operation
parameters in ROM instead of your setup/operation
parameters in NVRAM.
Refer to the ENV command (Appendix A) for the ROM defaults.
