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From:
[email protected] (Stephen Frede)
Newsgroups: aus.sources
Subject: PostScript printers in Australia
Message-ID: <
[email protected]>
Date: 16 Dec 86 09:37:21 GMT
Date-Received: 16 Dec 86 14:01:54 GMT
Organization: EE and CS, Uni of NSW, Sydney, Australia
Lines: 534
Here is an article I have written regarding PostScript printers and
laser printers in general. The only one I know of that is not in the
article is DEC's printserver 40, which retails for $91 000, and for
which I am getting more information. Apart from this I'd like any comments
you have, or any extra information you have. In a while I will post
a revised version of this to net.text, or whatever it is now.
Oh yes, I have seen the articles on DDL and C-Pscript in "Desktop
Publishing" and plan to incorporate that information, along with
netnews gossip.
------------------------------------------------------------------------
PostScript printers - the state of the nation
1. Introduction
Outlined here are the main features of the various
PostScript printers available in Australia, along with
miscellaneous comments. I believe everything here to be
accurate and up to date as at November 1986, but take no
responsibility for errors.
2. Marking engines
All the printers here are laser printers, utilising
basically the same technology, except for the Linotronics
and Agfa-Gaevert, which are described later. Most laser
printers are built around a "marking engine" of some sort,
which is already available. Often there are photocopiers
built around the same engines. It is these engines that
determine the physical characteristics of the printer. All
of the laser-printer marking engines described here provide
a 300 dpi (dots per inch) resolution. The major difference
between engines is their printing speed, measured in ppm
(pages per minute).
Basically, a laser scans a photosensitive drum,
altering the charge on the drum. The drum then passes
across toner, and picks it up, or doesn't, depending on the
charge at that point on the drum. The toner is then
deposited on paper, which goes under a fusing roller, so
that the toner is melted onto the paper. The details of
what charges go where are supremely unimportant, (in the
canon engine, the drum and powder are both positively
charged, with the laser discharging the areas where it
strikes), however one aspect of the mechanism is relevant.
Some engines are "write-black", which means that the toner
is picked up wherever the laser has scanned the drum, whilst
others are "write-white" which means that toner is picked up
everywhere except where the laser has scanned the drum.
There are two main results of this:
1. Because of charge leakage problems, a write-black
engine does not produce very good large areas of black
- they tend to be washed out. Write-white engines
produce much better large black areas. The effect is
not noticeable for normal text.
2. For engines of the same basic resolution, a write-
white engine produces smaller dots, and thus finer
lines than a write-black engine. This is because for
- 1 -
a given number of laser scans/cm, on a write-white
engine, the black is appearing between the scans,
which distance is less than the size of the beam-spot.
At 300 dpi resolution, a line only 1 dot wide should
ideally be 1/300 inch wide, but on a write-white
machine it will be about 0.8 of this width, while on a
write-black machine it will be about 1.2 times this
width.
This is not normally noticeable, but can produce
problems with some fonts. For example, some metafont
definitions need to know whether their output will be
on a write-white or write-black printer.
The circumference of the drum is in all cases less than
the typical page length. Page width is limited by the
engine, but page length is typically limited only by the
controller (esp. memory capacity).
2.1 Canon 8ppm engine (Canon LBP-CX laser-xerographic
engine)
Probably the engine in the most widespread use.
o Write-black
o Resolution: 300 dpi
o Max page width: ~215 mm (A4)
o Duty cycle has been quoted between 1K and 5K
pages/month, depending on who you ask. Apple recommend
about 4K pages/month.
o Engine life estimated at 100K pages.
o Uses a replaceable cartridge which contains both toner
and print drum, which means it's expensive (over A$100
for about 4K pages), but quality remains consistently
high throughout the lifespan of the printer.
o used in: LaserWriter, LaserWriter plus, QMS-PS800 and
many non-PostScript printers, such as the Impact,
Canon, etc.
o input tray capacity: 100 sheets
o output tray capacity: 20 sheets Many accessory devices
are available for Canon engine based printers,
including page-turners (so your output arrives page-
down, in the correct order); large paper bins and
- 2 -
stackers, collaters, etc.
UNSW Elec. Eng. have been running their Apple fairly
hard for quite a while, and must be pretty close to the
estimated engine life, but I believe that they are still
going strong and havn't had any serious problems with their
printer. Perhaps they'd like to comment.
In the US, various organisations will refill your toner
cartridge for a small fee. Apparently this can be done up
to two times before quality becomes totally unacceptable.
Discussion with various hackers leads me to believe that it
can be done yourself if you know how, and are VERY careful.
Also, it is essential to get the right type of plastic
toner, or you may clag your printer forever. (Remember the
imagen saga).
2.2 Toshiba_26ppm_engine
o Write-white.
o Replace drum every 100K pages.
o Used in: Dataproducts LZR 2660/5
o Resolution: 300 dpi
o Max page width: ~300mm (A3)
o Input tray capacity: upper - 500 sheets; lower - 250
sheets
Accessories available include face down output trays,
10-bin sorter/collaters and 1500-sheet feeders.
2.3 Ricoh_8ppm_engine
o Resolution: 300 dpi
o Duty Cycle: 10K pages/month
o Rated engine life: 600K pages
o Stacks face down (so your job comes out correctly
ordered)
o Input tray capacity: 250 sheets
o Max page width: ~215mm (A4)
- 3 -
o Uses toner cartridges similar (identical?) to the canon
engines.
o Used in TI Omnilaser 2108
2.4 Ricoh_15ppm_engine
As for the 8ppm, except:
o Rumoured to be a "second generation" engine.
o Duty Cycle: 25K pages/month
o Rated engine life: 1.5M pages
o Input tray capacity: two, each holding 250 sheets
o Used in TI Omnilaser 2115
2.5 Xerox_12,_24ppm_engines
o Resolution: 300 dpi
o Used in QMS-PS1200/2400
3. Printers
The marking engine is driven by a controller board, in
these cases developed by Adobe, which provides the
PostScript interface and does all the necessary image
processing. Adobe have made substantial improvements to
both their controllers and their firmware since the early
ones. The most significant change to the firmware is
evidenced between the Apple Revision 1 (PostScript version
23.0) and Revision 2 (PostScript version 38.0). The later
version of PostScript includes additional features, allows
handshake interpretation of DSR/DTR signals, as an
alternative to XON/XOFF, allows transmission rates higher
than 9600 baud, allows overlapping of page imaging with
execution of the next page and is substantially faster
overall. A document describing the changes was distributed
over the net from Adobe and is available from Softway.
Most printers come "standard" with the following Adobe
fonts: Times, Helvetica and Courier (constant width) each
in Roman, Italic (or at least oblique), Bold and Bold-
Italic, as well as a symbol font.
All the printers described here have both an RS-232
serial interface and an Appletalk (RS-422) interface, and
provide a Diablo 630 emulation capability. Other interfaces
- 4 -
and emulations are noted below where they occur.
3.1 Apple_LaserWriter
Certainly the most widespread of postscript devices.
Uses the Canon 8ppm engine. Originally, used PostScript
version 23.0, which had some (mostly documented) bugs and
limitations. If you use this, make sure you have a copy of
the software patch that fixes many of the bugs, and also a
copy of the a4 page definition routine. Both of these were
distributed over the net, and both are available from
Softway. The LaserWriter includes the standard set of Adobe
fonts. There are many satisfied LaserWriter customers, with
very few complaints. However, if at all possible, you
should try to get a Revision 2 LaserWriter, which is just a
PROM upgrade to PostScript version 38.0. An Apple
LaserWriter costs about A$8000 (inc. tax). Shopping around
is advised.
3.2 Apple_LaserWriter_Plus
This is solely a PROM upgrade to an ordinary
LaserWriter. It gives you a Revision 2 LaserWriter (ie
PostScript version 38.0) and a lot of extra fonts: Palatino,
New Century Schoolbook, Avant Garde, Bookman, Helvetica
Narrow and New Century Schoolbook, all in Roman (or Book, or
Light), Bold (or Demi), Italic (or Oblique) and Bold-Italic
(or whatever), as well as Zapf Chancery Medium Italic, and
Zapf Dingbats. The upgrade to an ordinary Apple LaserWriter
costs about A$1000 (inc. tax). If you have a Revision 1, it
may be good value to go for the upgrade, because you will
then have a Revision 2 printer. If you already have a
Revision 2 printer, decide if you want to pay that much just
for the extra fonts.
Also note that it is very advisable to have this
upgrade installed by a technician. The proms are VERY
sensitive to static, and it is very important to allow a
burn-in period before using the printer. If a technician
installs the upgrade, you don't have as many hassles if
things go wrong.
3.3 Sun_LaserWriter
This is just an Apple LaserWriter, but it costs
somewhat more because it comes bundled with some UNIX
software. I havn't seen the software, but ours (Softway's)
is almost certainly better.
3.4 QMS_PS-800
Very similar to the Apple LaserWriter Revision 2. Uses
PostScript version 38.0.
- 5 -
3.5 QMS_PS-1200,_2400
Use the xerox 12ppm and 24ppm engines respectively. I
don't know any more about these printers.
3.6 Dataproducts_LZR2660/65
Uses the Toshiba 26ppm engine (a write-white engine)
and PostScript version 39.0. The 2660 handles pages up to
legal size, while the 2665 handles A3. Cost is ~$A40000.
When we tested this printer, we found a PostScript bug
which shows up under certain conditions. Adobe have been
notified and are working on it. It uses the fastest engine
on the market, but remember that it will not actually run at
this speed unless you are doing multiple copies. The real
win is in the A3 paper capability. It is the only
PostScript laser printer I have heard of that will handle
paper this size. We printed some very nice larger-than-life
digitised images on this printer.
3.7 Apollo_Computer_Domain/Laser-26
This is just the Dataproducts printer descibed above.
3.8 TI_Omnilaser_2108
Uses the Ricoh 8ppm engine; has a page jogger (job
separator); includes two font cartridge slots. Includes
additional emulations: HP LaserJet/+, TI 855 DP/WP, HPGL
(Hewlett Packard Graphics Language, used by most HP
plotters). Includes additional centronics-type parallel
interface. The cost is A$9990.
Given the higher duty duty cycle and longer life, this
printer sounds like it could very well give the Apple and
other canon-engine based printers a run for their money.
The face-down stacking and larger paper bins that come as
standard are also useful, although these can be had as
accessories on most other printers.
3.9 TI_Omnilaser_2115
This is the same as the 2108, but uses the Ricoh 15ppm
engine, and has 3Mb RAM. The cost is $14500.
Again, this sounds like good value for money for a
faster printer.
3.10 Agfa-Gaevert_P400-PS
This printer uses LED array electro-photographic
imaging, rather than the more conventional laser scan, and
has a resolution of 406 dpi. The controller is a 68020
based 'Atlas' controller, which includes a 1Mb font cache
(by far the slowest part of printing on PostScript printers
is cacheing characters), two 2Mb memory (whatever that
- 6 -
means), and a 20 Mb hard disk. The engine speed is 16ppm
and apparently the controller usually manages to drive it
that fast. Comes with two paper bins, one of which holds
2000 sheets, and a face-down output stacker. Interfaces
additionally include a centronics-type parallel connection.
Sounds like a really nice machine, but unfortunately
Agfa-Gaevert in Australia say they don't even have pre-
release information on it, and that it will probably arrive
in Australia the middle of 1987. The cost is ~180K Francs
(US$28K).
Note that the P400-PS, although using the same marking
technology as the earlier P400, has a completely different
controller. Apparently the previous command language was
horrible and full of bugs. They won't even upgrade a P400
to a P400-PS because there are too many differences. Also,
the P400-PS is cheaper then the P400.
Delairco_Linotype_Linotronic_series
The Linotronic machines are not so much laser printers
as phototypesetters. Linotype advertise them as "laser-
setters", which is an apt name, because a scanning laser
beam images directly onto photographic film, or light-
sensitive paper. They feed from continuous rolls rather
than cut-sheet. Available as options are hard disks for
font storage (the entire Mergenthaler font library is
available on an 86 Mb winchester), and high-speed options.
I forget exactly which version of PostScript they use, but
it is a recent one, around 39.0.
Bureau services are available which will print stuff on
these machines from PostScript (that you have presumably
generated from a Mac or software from Softway).
3.11 Linotype_Linotronic_100
Resolution of up to 1270 dpi; additional centronics
interface; standard PostScript fonts; 17Mb (formatted) hard
disk. Print speed is up to 240 lines/minute. Cost is
A$69250.
3.12 Linotype_Linotronic_300
Resolution up to 2400 dpi; paper width up to 305 mm
wide (A3); print speed up to 585 mm/minute. Cost is ~A$96K.
3.13 Linotype_Linotronic_500
Resolution up to ~1500 dpi; paper width up to 457 mm
wide (newspaper size); print speed up to 1040 mm/minute.
Cost is > A$100K.
- 7 -
Random_notes_and_rumours
I have heard that an upgrade for canon engines is under
development, whereby the photodiode that produces the laser
is replaced, to increase the possible resolution to 400 or
even 600 dpi. However, apparently the main problem is that
the fine grade of toner that is required for such resolution
leaks out of existing seals.
Group IV Fax is defined as having a resolution of 400
dpi.
If anyone has any extra information about any sort of
laser printers, especially those with high-level input
languages, or has any comments on the information in this
document, I would appreciate hearing about it.
Stephen Frede
Softway Pty Ltd
P.O. Box 305
Strawberry Hills
NSW 2012
AUSTRALIA
Phone: (02) 698 2322
ACSnet:
[email protected]
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