6
FEPROM Firmware Update
KA681/KA691/KA692/KA694 firmware is located on two chips, each 256 K by 8
bits of FLASH programmable EPROMs, for a total of 512 Kbytes of ROM. (A
FLASH EPROM (FEPROM) is a programmable read-only memory that uses
electrical [bulk] erasure rather than ultraviolet erasure.)
FEPROMs provide nonvolatile storage of the CPU power-up diagnostics,
console interface, and operating system primary bootstrap (VMB). An
advantage of this technology is that the entire image in the FEPROMs may
be erased, reprogrammed, and verified in place without removing the CPU
module or replacing components.
A slight disadvantage to the FEPROM technology is that the entire part
must be erased before reprogramming. Hence, there is a small "window of
vulnerability" when the CPU has inoperable firmware. Normally, this window
is less than 30 seconds. Nonetheless, an update should be allowed to execute
undisturbed.
Firmware updates are provided through a package called the Firmware Update
Utility. A Firmware Update Utility contains a bootable image, which can be
booted from tape or Ethernet, that performs the FEPROM update. Firmware
update packages, like software, are distributed through Digital’s Software
Support Business (SSB). Service engineers are notified of updates through a
service blitz or Engineering Change Order (ECO)/Field Change Order (FCO)
notification.
Note
The NVAX CPU chip has an area called the Patchable Control Store
(PCS), which can be used to update the microcode for the CPU chip.
Updates to the PCS require a new version of the firmware.
FEPROM Firmware Update 6–1
