that the board has a linear current characteristic (normally it’s current limited). This allows more current to flow to the network as required by these special events. Billing (metering) tone filters Switzerland and Germany provide high frequency AC signals on the phone line for the purpose of billing customers. LC filters are provided on the European LIU's to prevent these billing signals from adversely affecting the data path and the DC hold circuit. An additional filter in the cable (for certain countries) may in some cases supplement these LC filters. These billings signals are not used in the US, so these filters are not present on the US LIU.
Fax page storage in flash memory Fax pages are the electronic images of the document page that have been scanned to be sent to another fax machine, have been generated to be sent by the computer, or have been received from a fax machine to be printed. The HP LaserJet 3330mfp stores all fax pages in flash memory automatically. Once these pages are written into flash memory they are stored until either the pages are sent to another fax machine, printed on the device, transmitted to the PC, or erased by the user. These pages are stored in flash memory, which is the non-volatile memory that can be read from, written to, and erased repeatedly.
The HP LaserJet 3330mfp has 4 MB of flash memory of which 3.4 MB is available for fax storage. The remaining 0.6 MB is used for the file system and reclamation. Adding RAM does not affect the fax page storage since the HP LaserJet 3330mfp does not use RAM for storing fax pages. Accessibility of stored pages Stored fax pages can be accessed by the user for reprinting or re- sending in case of errors. Other fax devices store fax pages in either normal RAM or short-term RAM. The LaserJet 3100 and 3150 use short-term RAM while the OfficeJet products use normal RAM. Normal RAM immediately loses its data when power is lost while short-term RAM loses its data about 60 minutes after power failure.
Flash memory maintains its data for years without any applied power. EN LIU (fax) functions and operation 105