There is a cartridge capping upgrade for older deskjet printers
available from hewlett-packard.  Older original deskjet and
possibly deskjet 500 units may have a black plastic slide with
rubber capping components in the cartrige parking area on the right
side (viewed from front) of the printer.  Newer printers have a
gray or white plastic slide.  The black plastic slide can allow
your cartridge to dry out.  There was and may still be information
packaged with ink cartridges explaining the situation.  HP placed a
coupon for a free upgrade kit to modernize old deskjets to the new
capping mechanism.  I did this on my printer and did indeed find
that the cartidges now last longer.

I don't have the information handy.  I suggest contacting your
nearest HP service center for information on obtaining the kit.

HP has upgrade kits that consist of electronics and mechanical
components that vary depending on the starting level printer and
the level to which you wish to upgrade.  I upgraded my original
desket to a dekjet 500.  The kit was fairly expensive.  You are
likely better off selling your old printer and purchasing a new
deskjet 500 now that prices have declined so much.  Upgrading an
original deskjet to 500 requires a fair amount of skill, but no
soldering.  Upgrading a deskjet plus to a 500 is involves swapping
the processor card and changing a few minor parts.  Contact your HP
service center for further information.

The PCL language used by Deskjets is considerably different from
the PCL used by laser printers, especially the newer laser
printers.  The biggest problem is dumb laser drivers that send a
raster end command after each scan line.  This makes no material
difference for lasers, but causes the deskjet to print the
accumulated raster.  As you might guess, the result is hideously
slow printing.  The new DOS Wordperfect print deskjet drivers are
still guilty of this particular behavior.  From the way Wordperfect
works, this would not be easy to change.  Windows Wordperfect works
efficiently unless you use the DOS drivers instead of Windows'.

The PCL4 dialect used in the Laserjet IIIP allows compression that
permits a full page 300 dpi image to be rendered with only one
megabyte of memory.  An uncompressed image could be as large as
about 909 Kbytes, but the printer needs about 300K of memory for
its internal house-keeping.  Laserjet IV models support banded
printing that allows incrmental download of the image with
compression in limited memory situations.  Deskjet downloadable
fonts are not compatible with laserjet fonts.

A single page from a laserjet only requires about 20 seconds.  This
is faster than any but the most trivial printing from a deskjet
printer.  The presumption, of course, being that the laser printer
has completed its warm-up cyle.

Until ink chemistry is changed, wicking resulting in image
deterioration is unavoidable.  I won't use the word impossible, but
matching laser quality output from a deskjet printer is unlikely.
Chosing an appropriate paper type helps, but does not eliminate the
problem.

Laser printers are more wastful of energy and consumable
components.  HP does accept return of spent toner cartridges,
mitigating the material waste problem to a degree.  Energy waste
could use more work.  Warm-up times have decreased, allowing
stand-by current consumption to be significantly reduced in the
laserjet IV.

Kyocera produces a laser print engine that employs an amorphous
silicon imaging drum with a replacable toner system.  The image
drum is good for approximately 100K copies.  It is a very nice
print engine.  I wish HP used the Kyocera engine.  Kyocera also has
a neat modular paper source and stacker system.

The recommended duty cycle for a deskjet is significantly lower
than any of HP's laser printers.  The pick-up pressure rollers are
subject to wear and I case confirm eventually do wear out.  The
usual symptom is that the printer becomes reluctant to feed paper.
The paper feed is integrated in a transport mechanism that is a
single part from HP service.  Replacement cost for the transport is
almost $200.  The feed rollers are not separately replacable,
though it would not be a difficult job for a competent technician.
I have disassembled and reassembled the transport on my own printer.

It depends upon the application which printer is best for you.  If
you only print 5 or 10 pages a day and are satisfied with the
appearance of output, the deskjet is a very good choice.  As noted,
the deskjet 500 is my choice for personal use.

