IBM 704 - Manual (Page 316)

Setting System-Board Configuration Jumpers
Setting the BIOS Write Jumper (J6A4)
19
Attention: Only a qualified, technical person knowledgeable
about boot block update utility programs should change the
BIOS Write Jumper (J6A4-1) setting.
J6A4
Writable
BIOS Write
1
1 2 3
This jumper enables updating the BIOS in flash memory with a
special utility. The factory default leaves this function enabled so
that you can update the BIOS from a startable diskette without
having to open the server covers and change the jumper.
Contact your IBM reseller or IBM marketing representative for a
copy of the utility that updates the BIOS.
298 PC Server 704 User's Handbook