27128 is a 16kB EPROM. The 3c509 (like many network cards) has a 28-pin DIP socket for a boot ROM up to 32kB. By convention PC BIOS's will recognize cards with boot ROMs and treat the boot ROM as a BIOS extension. This is how you boot from a SCSI adapter, for instance, even though your system BIOS knows nothing of SCSI. The network boot ROM code is a basic network card driver + minimal protocol stack (for IP, UDP and BOOTP/TFTP in this case) -- just enough to download a kernel. The process would be similar for booting Linux or other OS's which support diskless operation, though with different boot ROM code. Mark At 06:12 PM 4/10/98 +0000, R. Paul McCarty wrote: >Mark Shepard wrote: >> It has an ISA port, however, so I burned FreeBSD's bootp/tftp netboot loader into a >> 27128, plugged that into a 3c509 and the system booted diskless just fine > >What exactly did you do? What is a 27128? and how could you do this >without any disks for the bios to boot from? > >It sounds really neat, but maybe that's because I don't understand it. >%-) > >-Paul
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