Network Executive NetExec is an Alto command processor for invoking certain subsystems via the Ethernet without using the local disk. It is useful for rebuilding a smashed disk and for loading diagnostic programs when the disk is sick. Its user interface is intentionally similar to the standard Alto Executive. The program is invoked by holding down the
andkeys while pressing the boot button. You must continue to hold the keys down until a small square appears in the middle of the screen, then you can let go. NetExec and all of the programs invoked by it are boot- format files kept by 'boot-servers' -- programs which implement the Alto boot protocol. Most gateways and some other programs (such as Peek) contain boot-servers. When the NetExec arrives, it displays a ">" and blinks its cursor to indicate that it is ready for commands from the user. In parallel with this it displays a pair of lines near the top of the screen with its name and version number, a digital clock, and the machine's internetwork address. Typing "?" causes the NetExec to display a list of the boot-files it knows how to invoke. NetExec builds this list by probing the network for boot servers and asking them what boot files they are willing to give out. There are also some built-in functions which are listed by "?" as if they were boot files: BootDP0 Causes NetExec to boot the operating system on DP0 of the current partition. FileStat Prompts you for a boot file name and tells you all about it: its boot file number, the host from which the NetExec will obtain it, and the key combination which will boot it directly. Partition prompts you for a disk partition number. If this number is zero, NetExec tells you the current disk partition. If it is non-zero, it attempts to set the partition to that number. This command is only available on machines that support multiple disk partitions: Dorados and D0s. Probe Causes NetExec to probe the network looking for boot servers. If it discovers any new ones, it will add the new boot files to its list. This is done once automatically when NetExec starts, and whenever the user types an unrecognized command. Quit Boots DMT SetTime Causes NetExec to probe the network looking for a time server. If it discovers one, it sets the ------------ Copyright Xerox Corporation 1979 Network Executive January 12, 1980 2 Alto's clock from it. This is done once automatically when NetExec starts. In the future, common subsytems should be stored in a few places throughout the network, not on every local disk; perhaps the local disk can be eliminated entirely. Doing so requires a much better integration of network and OS facilites than currently exists. The NetExec described here is not intended to do this. There are several limitations in the current implementation: 1) Most boot-files are quite large. Typical boot- servers have space for only the few most commonly used programs. 2) Boot-servers typically run in machines with some other primary purpose, such as gateways, and must not consume too many resources. As a result, booting is slow and only one machine can be served at a time.