Booting Linux on Cisco 7513

Today I was reconfiguring a Cisco 7513 with a RSP 16 and a FastEthernet module inside.
So I did a erase nvram and a reload. After booting I was surprised to see the following in my Terminal:

Would you like to enter the initial configuration dialog? [yes/no]:
Loading pxelinux.0 from (via FastEthernet4/0/0): !!!
[OK - 13156 bytes]

So the box took an IP via DHCP and tried to netboot. (Un)fortunately it only breaks my terminal, so no worries! ;)