added netboot to SEBIOS.

sebios.lua

@@ -48,6 +48,23 @@ local function tryLoadFrom(address)
    local buffer = boot_invoke(address,"read",rl)
    return load(buffer, "=init")
   end
+ elseif component.type(address) == "modem" then
+  boot_invoke(address,"open",9671)
+  boot_invoke(address,"broadcast",9671,computer.address())
+  s=""
+  local bt = computer.uptime()
+  while bt+10 > computer.uptime() do
+   computer.beep()
+   local ev={computer.pullSignal(0.5)}
+   if ev[1] == "modem_message" and ev[4] == 9671 then
+    bt=computer.uptime()
+    if ev[6] == "." then break end
+    s=s..ev[6]
+   end
+  end
+  if s ~= "" then
+   return load(s,"=init")
+  end
  end
 end
 
@@ -58,6 +75,9 @@ end
 for address in component.list("tape_drive") do
  bootdevs[#bootdevs+1] = address
 end
+for address in component.list("modem") do
+ bootdevs[#bootdevs+1] = address
+end
 
 do
  local gA,sA = component.list("gpu")(),component.list("screen")()
@@ -79,7 +99,9 @@ do
   wl(" ")
   for k,v in ipairs(bootdevs) do
   if v == cba then S = " * " else S = "   " end
-    wl(S..tostring(k).." "..v.." "..component.type(v).." "..(component.invoke(v,"getLabel") or ""))
+  local e,l = pcall(component.invoke,v,"getLabel")
+  if not e then l = "" end
+  wl(S..tostring(k).." "..v.." "..component.type(v).." "..(l or ""))
   end
  end
  rdraw()