FEPROM Firmware Update
Overview
KA49 firmware is located on four chips, each 128 KB by 8 bits of
FLASH programmable EPROMs, for a total of 512 KB 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
Update Utility
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.
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. The utility may be run from either the
alternate console or the graphics console. The output
text will vary depending on the console used.
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