jlister@slhisc.uucp (John Lister) (05/11/91)
There have been several comments in the context of "I don't want to switch my LaserPrinter out of PostScript to print something because I can only do this a certain number of times before I damage the EEROM which stores config- uration information". This seems reasonable, except that on all the laser printers I deal with, there is a page counter maintained internally (and printed for information on the start page). If this doesn't live in the EEROM and is therefore updated on a page basis, where does it live? My page counter is still going strong after 50000 pages! John Lister. uunet!slcpi!slhisc!jlister
sch@ic7.EE.UManitoba.CA (R+C Schneider) (05/14/91)
>This seems reasonable, except that on all the laser >printers I deal with, there is a page counter maintained internally (and >printed for information on the start page). If this doesn't live in the >EEROM and is therefore updated on a page basis, where does it live? My >page counter is still going strong after 50000 pages! If you read the manual for the Apple LaserWriter, it says that the page count is stored in a special way to avoid wearing out the EEPROM. My guess is that the information is spread across multiple locations so that each is written less often. -- Roland Schneider University of Manitoba Electrical Engineering Winnipeg, Canada <sch@eeserv.ee.umanitoba.ca>
ed@mtxinu.COM (Ed Gould) (05/14/91)
>There have been several comments in the context of "I don't want >to switch my LaserPrinter" ... number of times before I damage the >EEROM. If [the page count] doesn't live in the EEROM and is therefore >updated on a page basis, where does it live? My page counter is >still going strong after 50000 pages! It's true that EEPROMS have a limited number of times that they may be erased and rewritten. It's also true that the printers maintain the count in EEPROM. However, they use some cleverness to avoid just rewriting the same location for each page. I no longer remember just what they do, but I remember something about using multiple words of EEPROM to store the count. I can also imagine retaining the count in RAM until power-off, and then writing into EEPROM, depeiding on whether there is enough power storage to guarantee time to complete the EEPROM write. It is a real issue with printer designers, though. -- Ed Gould No longer formally affiliated with, ed@mtxinu.COM and certainly not speaking for, mt Xinu. "I'll fight them as a woman, not a lady. I'll fight them as an engineer."
woody@chinacat.unicom.com (Woody Baker @ Eagle Signal) (05/15/91)
It is my understanding that the page counter is scattered through multiple bytes of the eeprom, such that no byte ever gets altered more than 10K times. Most of the current printers use battery backed ram (at least the QMS printers to). Cheers Woody
richard@pegasus.com (Richard Foulk) (05/16/91)
>>This seems reasonable, except that on all the laser >>printers I deal with, there is a page counter maintained internally (and >>printed for information on the start page). If this doesn't live in the >>EEROM and is therefore updated on a page basis, where does it live? My >>page counter is still going strong after 50000 pages! > >If you read the manual for the Apple LaserWriter, it says that the page >count is stored in a special way to avoid wearing out the EEPROM. My guess >is that the information is spread across multiple locations so that each >is written less often. The manual for the LaserJet-3 Adobe PostScript cartridge (which may not constitute a "regular" PS printer) says this: The page count is current as long as the printer is powered on. When the printer is powered off, the page count is rounded-down to the nearest 10 page increment and recorded in memory. This value cannot be reset. The printer does seem to take an extra moment or two to fully power down. -- Richard Foulk richard@pegasus.com
dall@plains.NoDak.edu (Brian Dall) (05/19/91)
I don't have the manual in front of me for the LaserWriter II/NTX we have at work, but I thought I remembered seeing something in there about the LW II/NT having a problem with the EEPROM wearing out, but the LW II/NTX not having the same problem. I'll have to look it up, or perhaps someone has the manual handy and can check that. I don't know what the technological basis is for making such a statement. Is it different hardware? Brian Dall
henry@angel.Eng.Sun.COM (Henry McGilton) (05/20/91)
In article <10479@plains.NoDak.edu>, dall@plains.NoDak.edu (Brian Dall) writes:
* I don't have the manual in front of me for the LaserWriter
* II/NTX we have at work, but I thought I remembered seeing
* something in there about the LW II/NT having a problem with
* the EEPROM wearing out, but the LW II/NTX not having the
* same problem. I'll have to look it up, or perhaps someone
* has the manual handy and can check that. I don't know what
* the technological basis is for making such a statement. Is
* it different hardware?
From the Apple LaserWriter Reference:
You can write new values to the EEROM, which can store the
persistent parameters only a limited number of times before
wearing out. Each location of the EEROM is capable of
approximately 10,000 writes. For this reason, you should use
the EEROM only for parameters you expect to change infrequently.
The copy count is an exception -- it is implemented in such a
way that the wear is distributed over many locations.
Note: the LaserWriter IINTX uses ZPRAM in place of the EEROM.
ZPRAM can be written to an infinite number of times. Therefore,
the statements just given regarding storage of the persistent
parameters in the EEROM does not apply to the LaserWriter IINTX.
........ Henry