Upgrading Software - Xerox ii LINXSolid Inkjet 100 Service Manual

Upgrading Software

6-58 ii LINX™ Solid Inkjet 100 Printer Service Manual
The operating system of the Solid Inkjet 100 printer is capable of
reprogramming the embedded software using flash memory
technology. When instructed to flash, the OS overlays a special boot
program, the flash monitor, onto RAM and reboots the processor. The
flash monitor then boots and downloads a formatted data stream
containing executable object code into the flash ROM. After
completing the flash, the monitor reinstalls the nominal boot
program.
The main value of this functionality is found during printer
development, when software changes are applied daily. To support
daily flashing, the OS spawns a daemon that listens for a remote
flash request. A flash instruction can also be initiated from the OS
command shell using flash () . Either of these mechanisms load the
flash monitor described above. The formatted data stream is received
remotely, via the network or parallel port.
However, when the printer is booted in Customer Mode, the flash
daemon is not active because the Ethernet connection that services
the OS is disabled. The only available Ethernet pathway into the
printer is attached to the PostScript Interpreter. It is useful to retain
the ability to download the embedded software remotely, in part
because it simplifies upgrades in the field. Thus the PostScript
language has been extended to permit remote flashing during any
boot mode.
The custom operator updateflash is used to download the formatted
data stream used by the flash monitor into the frame buffer RAM.
The flash monitor is then booted and programs the flash ROM using
the data stream supplied not remotely, but locally from RAM. If the
attempt to flash from RAM subsequently fails, the monitor reboots
itself and expects data to be supplied remotely.