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Bruning Zeta 924 C/D size 8 Pen Plotter

I acquired a Bruning Zeta 924 8 Pen C/D size plotter in 1997.

This web page seems to be the most useful source of information on the web for the orphaned Zeta plotters; I get many quite a few inquiries and statements to that effect. The information on this page should work for the Zeta 924 and Zeta 936 and probably also applies to the Zeta 824 and Zeta 836 which were apparently fairly similar (to the point where the dip switch settings are apparently the same or similar enough that you can get one model to work with the settings for the others).

[Zeta Plotter Image] [Pen Holder Image] [Shuttle Side View] [Shuddle bottom View]

As of11/4/97, I could send HPGL commands to the plotter and get it to move around. I had my plotter draw string art using a simple shell script.

It appears that Nicolet was bought out by Bruning, who reportedly mismanaged the company badly, and sold it to one of the original owners (circa 1991) at which point it apparently became Zeta Graphics or Zetagraphics. There is no affiliation with the folks who own the domain Zeta Graphics reportedly went out of business in October of 1995. The company laid of the whole engineering department in the summer of 1992.

This plotter speaks HPGL. It can also speak Zeta's proprietary GML, emulate tektronix TGE, emulate a calcomp 960, emulate IBM-GL, and emulate a 80 or 132 column line printer.

This plotter seems to be a pretty well engineered, high performance, servo motor driven unit, although the front panel user interface is convoluted and they should have made the pen holder bigger so you could use standard pens.

This is not a flatbed plotter. It has a small drum platten with vacuum holddown and pin-feed mechanism. This plotter takes 25-3/4" wide pin-feed roll paper. The pin-feed holes are 25-3/8" apart and spaced the same as on standard fanfold computer paper. The tractors tear off to yield 22" or 24" wide papor. For single sheet use, it has a shuttle rail assembly with two rollers that press the paper against the platten (although I am missing one of the shuttles).

The unit appears to work with fanfold computer paper but that limits you to half the plot width. It appears to halfway work with non-pinfeedpaper without the shuttle rail but I suspect it would not maintain registration. Small sheets (like 8-1/2x11) which have been laying flat come loose when plotting near the edges but 24" wide banner paper (on rolls) from the office supply store appears to feed pretty well as long as you cut it a few inches oversize on each end so it doesn't break vacuum; it can run test plots at full pen speed (fast) this way with the paper making a loud report as it hits the stand although I suspect that the registration may not be very good using this method.

When you press the Liquid Ink pen, the plotter becomes a 4 pen instead of 8 pen plotter, skipping every other pen. From this, I assume that you need a different pen holder that holds 4 wider pens. I am thinking about machining a holder that will accept HP plotter pens since these are very readily availible. They might need a small portion of the flange removed so they don't collide.

Switch Settings

There are three banks of dip switches and 2 thumbwheel switches. Via experimentation, I found the two thumbwheel switches set pen speed and pen pressure. I have found a switch combination that initiates a test plot, although this can be done from the front panel.

Chris Horihan <$gt; sent me some DIP switch settings from a Zeta 8A plotter which also work on my plotter:
0=up or open.
SW01:  01100000    SW02:01111100    SW03:01111100
I am still using these settings, although I now have the manual.

The dip switch settings are very complicated, in part because they vary by mode.

0=up or open
SW01  1-7  0110000   Selects HPGL/RS-232 mode
      8    0         no power stand

SW02  1            Output Identification (OI) Command response
           0         emulated HP model
           1         Zeta model number
      2            On-line/off-line selection
           0         need .Y or .(
           1         do not need .Y or .(
      3            Default handshaking protocol
           0         Hardware handshaking
           1         Software handshaking
      4           "IN" command respons
           0         No page Advanced
           1         Page advanced
      5           Emulation
           0        HP7585
           1        HP7475A
      6    0      not used
      7           Plot limits
           0        Clipping 
           1        Simulated Mechanical
      8           Cut sheet or Continuous
           0        Continuous
           1        Cut sheet

SW03  1-3         Baud Rate
           000      110
           100      300
           010     1200
           110     1800
           001     2400
           101     4800 
           011     9600
           111    19200           

      4-5         Parity
           00       None/Space (0)
           10       Even
           01       Odd
           11       None/Mark (1)
      6-8         Auto Repositioning or Drawing Size selection

SW04A             Pen Speed, 1=10%...9=90%, 0=100%
SW04B             Pressure: 0=minimum...9=maximum


The plotter originally shipped with a smart cable; if this is not availible, you will need to make a special cable. It should be a null modem cable (reverse TD/RD, etc.) and pin 20 on the plotter should be wired to CTS on the computer since the plotter apparently asserts handshaking on the wrong pin (which is also true for HP plotters). HP recommended pinouts have been reported to work. A Mac Serial Pinouts page is handy for understanding the mac pinouts but the cable shown there does not have prober handshake (see table below). The table below shows the recomended pinouts in the Zeta manual.

Zeta 25 pin PC 25 pin PC 9 pin Macintosh 8 pin
1 FG 1 FG
Shield Shield
2 TD 3 RD 2 RD 5 RXDB-
3 RD 2 TD 3 TD 3 TXDB-
7 SG 7 SG 5 SG 4 GND
20 DTR 5 CTS

Wang PC requires: 1 straight through, 7 straight through, 2&3 swapped Zeta 20 to Wang 5, and connect 4, 6, and 8 on the wang together.

If your cable does not have proper handshaking, the plotter may handle very small plot files (which fit entirely in the plotters bufffer) but fail for larger files. You might also try changing the dip switch for XON/XOFF and enabling responding to XON/XOFF on the computer too.


Front Panel Controls

Magic codes(PMS)

The front panel user interface was designed by a madman; any sensible engineer would have allowed you to enter two digit codes by simply typing - after all, there are plenty of buttons availible for 0-8. Instead you have to use this proceedure:
  • While holding the center diamond down, press F5 (pause).
    The plotter will beep and the light above F5 will blink until you exit PMS mode
  • Press F2 to cycle the pen number lights through 1-8 until you get the digit you want, then press F4 to enter the most significant digit
  • Press F2 to cycle the pen number lights through 1-8 until you get the digit you want, then press F4 to enter the least significant digit
  • Repeat the last two steps to enter more PMS codes or F5 to exit PMS mode.
Single Pen
Slow Pen Up Speed
Single Step Mode
Halt on limit
Disable Slow Media Pull
Display controller Processor PROM Version Number
Display Plotter processor PROM version number
Pen Type: Liquid Roller (default)
Pen Type: Nylon tip
Pen Type: not used
Pen Type: Ball Point
Media Type: Translucent (default)
Media Type: High-quality bond
Media Type: Clear Inking Film
Media Type: Matt Film
Media Type: Vellum Type E
Test patterns (23 requires special cable) When using the pen and media type PMS settings, set SW04A=0 and SW04B=5.

A former zeta engineer informed me that the bizare front panel interface was an anachronism from before they added the additional buttons.

Rescaling/rotating plot

  • Press "SET SIZE"
  • If you want to rotate, press F5
  • Press the size of the desired plot (A,B,C,D...>
  • If the incomming data file is in portrait format, press F5
  • Press the size of the incoming plot data (A,B,C,D...)


  • Resolution: 0.025mm, 0.05mm, 0.001in., 0.002in, or 0.025in.
  • Accuracy: +/-0.1% of movement on polyester matte film
  • Repeatability: single pen: 0.004in, pen to pen .005 in
  • Acceleration: On axis 3.0g, at 45 degrees 4.2G
  • Plotting area:
    924: 61.7cmx43.9m (24.1in x 120ft), ISO A4-A1, ANSI A-D eng/arch
    936 86cmx43.9m (34in x120ft), ISO A4-A0, ANSI A-E eng/arch
  • Pen Delay Time: 0-255ms
  • Baud Rate: 110, 150,300,600,1200,1800,2400,4800,9600,19200
  • Interface: RS-232-C and optional IEEE-488
  • Pen Speed: 30 inches per second, 76 cm/s at all angles
  • Dimensions
    924: 42"Wx12"Dx10"H, 40lbs
    936: 48"Wx12"Dx10"H, 50lbs.
  • Power requirements: 100/120/220/240V (must be selected), 47-63Hz, 100W avg, 120W Peak. Heat dissipation 340BTU/hr (avg) - 400btu/hr peak.
  • Certification pending: CSA, FCC B, UL, VDE B.
  • Operating Environment: 10-40 degrees celsius (40 to 104 fahrenheit), up to 70% RH at 40 degrees C, up to 30% RH at 10 degrees C
  • Storage environment: -40 to +70 degrees Celsious, 5%-95% RH (non-condensing), -150m to 15,000m (-500ft to 50,000ft) altitude.

Supplies and accessories

Here a links to some companies which sell plotter supplies. Some of them may have supplies which fit Zeta plotters.
  • Chartpak has Z style Koh-i-noor pens which direct fit the zeta plotter (I think the 4 pen holder is required, not the 8 pen holder).
  • Western Numerical Control sells zeta compatible pens and pin-feed paper (on another page). I think their Z style DPP pen fits the 4 pen holder (not the 8 pen holder).
  • TMS Plotter specialists, 23621 Ridge Route Dr.,Laguna Hills, CA 92653. (949) 837-2324. Reportedly has many old zeta plotters that may be purchased for parts.
  • Surveyors Supply specifically sells plotter points and Zeta Adapters. Unfortunately, this link is now broken due to their rearranging their web site (although it still gets you to their poor quality web site in general).
  • BMAappears that they may sell paper for this machine. Poor web page.
  • OCE sells plotter supplies but their web page has very little information. Reportedly, they purchased the supplies portion of the company when zeta went out of business.
  • I checked at Plotter Supplies, Inc. may also. Poor web page.
  • The Drafting Clinic
  • Staedtler-Mars home page. Contact info only.
  • KOH-I-NOOR Has a limited selection of refillable liquid ink pens for the Zeta plotters. Terrible web site.
  • Consolidated Reprographics
  • Makepeace has drawings and prices of some of the pens they have availible. They have a Classified Ad's section which has featured at least one Zeta plotter.
  • Exac-Tac sells rolls of vinyl which might be usable with the zeta.
  • Rick Fruler reported using Fischer SpacePen ball point pen refill cartridges with a pen holder supplied by Zeta in his Zeta 3640 plotter. Please note that I do NOT condone doing business with Fischer SpacePen. They have a dreadful web site and a web master who is not only incredibly obnoxious but turns out to be a usenet spammer as well. Also note that the 3640 plotter apparently takes different pen sizes and adapters from the 800 and 900 series, anyway. The 900 series can use 3" pressurized ball point pen refills (with adapters) whereas the 3600 series uses a more common 3.5" pressurrized ball point pen refill.
  • WestNC has pens/paper.


The hp2xx package can translate HPGL to metafont, emTeX, epic, encapsulated postscript, simplified HPGL, pcl, img, pbm, pcx, rgip and can provide X11, DOS VGA, Amiga, or Atari previewing. This package includes a listing of the two letter HPGL commands. More information can be gleaned from the source.

The program hp2xx contains code to read and write hpgl and also contains partial documentation on HPGL. It has a list of 119 different two letter commands and what their purpose is but does not describe the parameters.

HPGL Information

  • See hp2xx (above)

    Here are links to a couple documents that describe HPGL and HP-GL/2:
    HPGL: HTML or silly zip file
    HP-GL/2 html or silly zip archive

  • HP 7550A Interfacing and Programming Manual 07550-90001 availible from "HP's Support Material Organization"
  • hpgl2ps translates HPGL to postscript. It needs a makefile and some patches to compile under unix and I haven't fixed the bugs yet. There is an older version which (almost) compiles under unix in the CTAN archives; it has illegal standard library calls (fprintf with first argument format string, strcpy with first argument as a string constant).
  • hp2ps teaches a postscript printer to recognize HPGL (except for a minor problem with the label command being terminated with a ^C).

You can write programs to create hpgl in any language. Assembly language would be more cumbersome than a high level language for this purpose.

I don't know of any site which has the full documentation online. You can order manuals from Hewlett Packard which would document this; the owners manuals for specific plotters (such as the HP7475) contain the documentation for the HPGL commands supported by that model. Some manuals availible from HP :
HP-7475 Operation and Interconnection Manual 07475-90002
HP-7475 Interfacing and Programming manual 07475-90001 This should have documentation on HPGL commands.
Plotter Comparison Guide 5954-7124 (for HPGL)
HP-GL/2 Reference Guide 5959-9733 (for HP-GL/2)
HP-GL/2 Comparison Guide 5959-9734 (for HP-GL/2)

At least one book is availible for HP-GL/2: The Hp-Gl/2 and Hp Rtl Reference Guide : A Handbook for Program Developers . Another book, has a chapter on HP-GL/2 which is readable online.

The following example program will plot two squares. Do not include the comments.

IN;                      // Initialize
SP1;                     // Select Pen 1
PU;                      // Pen up
PA0,0;                   // Move to coordinates (0,0)
PD;                      // Pen Down
PA0,1000;                // Move to (0,1000)
PA1000,1000;             // Move to (1000,1000)
PA1000,0;                // Move to (1000,0)
PA0,0;                   // Move to (0,0)
PU;                      // Pen up
PA1000,1000;             // Move to (1000,1000)
PD;                      // Pen Down  
PA1000,2000;             // Move to (1000,2000)
PA2000,2000;             // Move to (2000,2000)
PA2000,1000;             // Move to (2000,1000)
PA1000,1000;             // Move to (1000,1000)
PU;                      // Pen up
PG;                      // Eject Page (optional)
Other commands exist to print text, arcs/cicles, etc.

Scientific/Engineering applications for linux


  • HPGL Document test. This page gives a test document and also links to HPGL viewers under various platforms.
  • xhpgl-2.0X11 based HPGL viewer.
  • WEBPlotter is a NETscape plug in which plots HP-GL files. No unix versions.
  • Applixware can generate HPGL from the Applix graphics and presents programs.


  • sells a HP2DXF utility that converts HPGL files to DXF. A restricted demo is availible. The list of supported commands provides a little bit of documentation on the HPGL language.

Help wanted

  • Sources of pin-feed paper for this plotter, besides Quint
  • Sources of pens for this plotter, besides Quint
  • Sources for 3" long pressurized ball point refills (NOT manufactured by fischer space pen) or liquid refills for the labyrinth ink sensible ball point pens.
  • Schematics, service manual
  • pen-holders for this plotter.
    If anyone has a spare 4 pen plotter adapter they are willing to sell cheap, let me know.
    UPDATE: Someone was kind enough to give me one of these pen holders. Thank you very much.
  • Adapters to accomodate standard HP plotter pens
    These would be rather tricky given the space constraints.
  • Adapters for non perforated paper.
    I have the shuttle rail and one of the two shuttles but I need the other shuttle rolller and the side mount clamps (although I could always use a small C clamp for the latter).
  • Copy of the manual, particularly the DIP switch settings.
    No longer needed. Purchased from Quint.
  • Since I get many enquiries on other models, if anyone knows the differences between various models that would be useful to other people.
  • If you have the dip switch settings for a different model, please compare them to the ones here. If they are the same, let me know. If they are different, taking the time to type up the settings would help other people who acquire the same model.
  • If anyone has specifications for the GML protocol, they would be useful to some people (done). I am content (and prefer) to use HPGL but some owners of older plotters may not have that option. A C program which translated from HPGL to GML would be useful to those people.


Quint Computer Solutions offers supplies and paid support/service for the zeta plotters. Quint was apparently started by a group of ex-employees of Zeta Graphics Company which went out of business on Oct 25, 1995. Their phone numbers are 1-800-366-7568 for Tech Support and 1-800-733-7568 for supplies.

Quint Computer Solutions
1076 Horizon Drive, Suite 4
Fairfield, CA 94533
Phone: 800-733-7568 (supplies)
Phone: 800-366-7568 (Tech Support)
Fax: 707-435-1074
Phone: 707-435-1070 (switchboard)
Email: "Gary E. Crowson" <>.  You may reach a Rodney McClelland instead.

Quint has parts and supplies you will have trouble finding anywhere else. I have done business with them. I was not impressed. Well actually, I was impressed, but the impression was not favorable. Their ability to waste your time and mess up an order was considerable and their "catalog" descriptions range from poor to inaccurate. I have grown tired of trying to get them to give me a part number and a price for a replace shuttle; even though they apparently have the part, giving me these two little pieces of information apparently taxes their mental abilities to the breaking point. They have also disturbed my sleep by making unwarranted phone calls in the morning. Although they have an email address and even managed to stumble accross my zeta page via one of the search engines, they just do not seem to grasp the concept of email.

Here are some excepts from their catalog, which are intended to give you an idea what they have since they are not competent enough to have a web page of their own (I shudder to think how badly they would mess it up if they did) and it can take quite a while to get their print catalog via US Snail. I have just listed parts which fit the 924. These will also probably fit other plotters in the 900 series and many also fit plotters in the 800 series and the 3600, 5400, and 5500 series. It appears that the 800 series cannot take the ink sensible pens and that the 3600/5400/5500 series of plotters can take pens 3.5" high whereas the 800 and 900 only take 3" high pens. The "CP" models appear to take 3" ballpoint only. These are from an undated catalog which I received some time around the end of 1997 or beginning of 1998. I have absolutely no intention of keeping this list up to date.

Part numbers given for black, other colors availible

300401   Nylon Tip  0.3mm black                    6/pack  $15.00
300400   Nylon Tip 0.3mm blk,bl,rd,gr,vi,or,cy,mag 8/pack  $20
300421   Fiber Tip 0.7mm black                     6/pack $21
300420   Fiber Tip 0.7mm blk,bl,rd,gr,bi,ir,cy,mag 8/pack $26
300831   Standard Rollerball Pens 0.4 to 0.6mm     6/pack $14
300829   Standard rollerbal asst 0.4 to 0.6mm      8/pack $20
300841 Labyrinth rollerball black 0.4 to 0.6mm       6/pack $40
300852 Labyrinth rollerball asst 8/pack                     $43
301551 Ink Sensible Labyrinth Rollerball black 0.4 to 0.6mm 8/pack $48.00
303211 3" Pressurized Ballpoint Fine black 0.8mm     5/pack  $45
303331 3" Pressurized Ballpoint Medium black 1.1mm   5/pack  $45
303351 3" Pressurized Ballpoint medium black 1.3mm   5/pack  $50
above pens require 8 pen block assy.
Presurized pens availible in black, blue, red, green, brown, violet,
and orange but not as assortments.

Stainless steel technical tip pens for vellum (require 4 pen block assy)
301011 Stainless Steel Technical Tip   0.25 Ex fine black  4/pack $30
    only in black
301021 Stainless Steel 0.35mm Fine   4/pack                       $30
301020 stainless steel 0.35mm Fine blk,bl,rd,gr   4/pack          $30
301031 Stainless steel 0.50mm Medium black        4/pack          $30
301030 Stainless steel 0.50mm blk,bl,rd,gr        4/pack          $30
301041 Stainless steel 0.70mm Bold black           4/pack         $30
Tungsten technical tip pens for matte film (require 4 pen block assy)
301161   0.25 Ex Fine black                        4/pack $46
    also avail in red or blue
301171  0.35mm Fine black                          4/pack $45
    black only
301181  0.50mm Medium black                         4/pack $45
   availible in black, blue, red, green
301191  0.70mm Bold Black                           4/pack $45
   also avail in red

Pen holders and adapters:                                                       
001-300895-S Ballpoint Adapter   8/pack    $42.50
001-850847-S Standard 8 pen block  1 each   $75
001-850854-S Liquid Ink 4 Pen Block 1 each $105.00

001-840055-S Paper Roll Adapter       1 each $31.50
    What they fraudulently call a paper roll adapter is actually
    merely a replacement part for a paper foll adapter.  You get
    one of the two expanding rubber rollers that you stuff in the
    end of a paper roll so you can hang it on the brackets
    (not included) which bolt to the back of the plotter.
    Worse, yet, instead of changing this description, they
    wasted my time with a pathetic attempt to justify it.

The following two items are not really plotter specific, but if you
are ordering from them anyway can be somewhat useful.
000-200989   Cutter Key               1 each $1.75
   This is just a keyring size utility knife with "Zeta" printed on it
   which is useful for cutting paper against the grove in the front
   of the plotter.
000-200990   Zippy media cutter       1 each $5.00
   This is a plastic razor blade paper cutter which is typically sold
   for cutting newspapers.  The (replaceable) blade is captive inside
   the unit.  You slide the paper into a groove in the unit and
   then slide the unit along to cut the paper.  Works better than
   scissors.  You can probably buy these at office supply, "dime", "dollar", 
   or department stores.

cables are availible


202110     Translucent Bond   22"x120'PF  1 roll/box   $24
202310     Translucent Bond   24"x120'PF  1 roll/box   $24
202130     High Gloss Bond    22" x 60'PF  1 roll/box  $24
202330     High Gloss Bond    24" x 60PF   1 roll/box  $22
202120     Vellum             22" x 120'PF  1 roll/box $50
202320     Vellum             24"x120'PF    1 roll/box $50
202140     clear inking Film 25.6"x50' NPF  1 roll/box $90
202150     Matte Film 2DM/Mylar 25.6"x60'NPF 1 roll/box $70
PF=perforated, NPF=no perforation

Using the plotter with Windows 95


I do not condone the use of windows 3.x, 95, or NT. However, I have had a number of questions about this and I have printed a test page from Windows 95 a long time ago.

Use the Dip switch settings shown elsewhere on this page.

For a cable, I think I used a Smartcable (which came with my plotter), with the "smart" end connected to the "modem" port on the plotter and the other end connected via a gender changer and, possibly, a 9 to 25 pin adapter to the PC serial port.

I configured Windows 95 to talk to a HP7475 plotter. This worked but limited the page size to A/B. You can work around this problem by using the plot scaling (awkward) or by selecting another HPGL (not HPGL/2) plotter which has a 24" or 36" wide carriage, as appropriate. Try a HP7585A for a 24" wide model. For a 36" model, HP7586B has been suggested. Before trying one of the other models, I would suggest using the HP7475A setting to make sure you can talk to the plotter ok before introducing other variables.

Then print a test page.

If you want to use a CADD package or other software which speaks HTML directly, trying to go through the windows printing system could break things. There is a good chance you will get HPGL commands themselves written on the page instead of executed. You might have better luck configuring the plotter as a generic text printer or getting the software to talk to the COM port directly.

I have gotten a number of emails from people wanting windows 95 or NT drivers for various zeta plotters. If your plotter can support the HPGL language, then the instructions here should work. If your plotter model only supports GML, I can not help you. Maybe quint can. If anyone knows anything about GML drivers, send me an email so I can post the info here.

Note that it is extremely rude to email a computer professional with questions about operating systems such as Windoze that such computer professionals clearly do not condone the use of.


Using the plotter with Linux and other un*x compatible OSes

Here is a sample script to produce a simple test plot under linux. It assumes your plotter is attached to /dev/cua1.

stty 9600 -parenb -parodd cs8 -crtscst -ostopb </dev/cua1
echo "PU:" >/dev/cua1
echo "SP1;" >/dev/cua1
echo "PA 0,0;" >/dev/cua1
sleep 5
echo "PA 20000,20000" >/dev/cua1
for i in 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000; do
   for j in 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000; do
      echo "PU;" >/dev/cua1
      echo "PA $i,0;" >/dev/cua1
      echo "PD;" >/dev/cua1
      echo "PA $j,20000;" >/dev/cua1

Other Zeta Models

The 824 and 836 are apparently very similar. The 936 is identical except it supports wider paper.

If you have some other model, please send the following information if possible (to help others, not me):

  • Model #
  • Similar models which differ only by size or other minor differences
  • Format: (i.e. paper sizes, pinfeed/cutsheet/roll)
  • Max plot speed:
  • Emulations: Particularly, does it do HPGL
  • Dip switch settings: If not the full settings, provide at least one combination which is known to work and specify language (preferably HPGL) and serial port speed, parity, etc.

The zetadraf 900 was entirely different from the 912/924/946.

Pen compatibility:

  • One type: Bruning 912, 924, 924PS, 936, 936PS, 987, Zeta 968/PS, nicolet 8, 922, 924, 924CS, 836CS, 887. Actually there were two pen holders which took two sizes of pens.
  • Another type: Bruning Zeta 600, , 650, 675. Other brands.

Other Zeta Owners

If you contact me regarding a Zeta plotter, please let me know whether or not you would like me to add your name to this section.

  • Rick Frueler ( has an old Zeta 3640 (3600 series), 4-pin 36" wide pin feed plotter. He is looking for help obtaining parts (particularly belts used to drive the pen carriage and the drum).
  • Chris Horihan has a Zeta 8A plotter which has similar dip switch settings to my Zeta 924. He would like to get windows 95 to drive the Zeta 8A but has not been successful with a HP7475A driver.
  • Michael McFadden <> has an 836CS model.
  • Pete R Stumpf <> has a model 836.
  • Dr. Uwe Seidel at Agfa is looking for the Fundimental Plotting Subroutines code in C (preferably) or fortran for their Zeta 912 plotters.
  • Ronald Karnesky < > has an 836CS model with no manual.
  • Randy Gordon-Gilmore used to work as a mechanical engineer on the 912/924/936 line. He does not have schematics, etc. He owns a Zetadraf 900. He has a page with some Zetadraf 900 Notes
  • Eric Hungerford is using a Zeta 842A and sent me info on the HP cables working and regular null modems not. He also notes that 1 stop bit vs. 2 is important.
  • Hal Brehe is the orignal owner (with manuals, etc) of A Sweet Pea Six Shooter (not to be confused with the original Sweat Pea plotter which was not HPGL compatible) which was actually the Zeta Sprint. The Sweet Pee 6 shooter was an A/B format, six pen, 14ips HPGL plotter. Suggested dip switch settings: #3 OFF, all others on; works with Win95 HPPLOT.drv.
  • Niklaus Stoll has schematics and the fortran manual.
  • has fortran manuals and disk.
  • has some zeta pens to sell and maybe an E size plotter.


  • Plotter plots a small file ok but has trouble on larger files. Plotter lights indicate an error 81.
    You probably have a flow control issue. Make sure your cable is wired properly and the flow control settings on the plotter and computer match. Note that you need an unorthodox cable pinout to use hardware handshaking (described above).


Some later 924/926 models had ink level sensing. Apparently, the company prototyped vinyl cutters but they probably never made it into production.

Vinyl Cutting

A number of people have expressed interest in vinyl cutting. As far as I know, no one has tried this and gotten it working yet. Some considerations:
  • You can buy swivel knives from Xacto at some craft stores that might be a place to start. But if you can get a swivel knife that was made for a vinyl cutter that might work better.
  • The plotter must have enough torque to move a knife, not just a pen. This isn't likely to be a problem with the big zetas.
  • The downward force required on a knife is probably much harder than on a pen. The lifting force might be higher as well if the knife assembly is heavy.
  • There must be some sort of depth stop adjustment on the knife to prevent cutting into the backing or plotter.
  • You may want to write software (hp2xx might be a could place to start from) that adjusts the coordinates to compensate for the knife blade offset based on the angle of the last cut. You probably want enough friction in the swivel so the knife does not swivel during pen up travel.
  • There is a lot more info on the web about vinyl cutting than when I originally wrote this. A teflon backing pad (cutting mat) is needed to protect the plotter platten. www.signcatalog has an 18"x20" sheet of teflon and they have blade holders for some brands of plotter/cutters. Mastergrave, roetgeun, blade holders for various plotters. One vinyl cutting machine lists blade force as adjustable from 30g to 500g, another only goes up to 200g. Some crude measurements suggest the zeta 924 is capable of around 250g.

Market Value

A number of people have asked what these plotters are worth. I paid $100 for my 924 a few years ago. HP plotters would be worth more because: they originally cost more, the company is still around, and supplies are much more readily availible (including at surplus prices). If you buy a used zeta and it dies, you are pretty much stuck. If your used HP dies, you can buy another on ebay and use the same supplies. Large HP plotters seem to go for $100-$350 on ebay.

Other zeta plotters

Bruning Zeta 600,650,675

These do not take the same pens as the zeta 9xx series. However, you can use koh-i-noor A series pens with the 7155SLV adapter (just do a google search on 7155SLV). About $20 for the adapter sleeve and the pens are about $15 for a 4 pack for rollerball and fiber tip pens and $39-$56 for a 4 pack of DPP pens (disposible liquid ink). This pen adapter fits many other plotters including:
Bruning Zeta 600, 650, 675
Graphtec FC2OOO FD5200. FD6300, FP6300, FP7200. FP6302, FP7100. FX5000 FX5100, GP1002. GP1002A. GP1003. GP1004, GP1102. GP1102A. GP2000E, GP2005IE. GP2100/E, GP21OS/F, GP2106. MP3OOO, MP4100, MP4200. MP4300, MP4400, PD9OOO. PD9100, PD9300. PD9400,
Mannesmann Tally Pix~ Pixy 3,
Numonics 5412, 5424, 5460, 5624, 5860, 6412, 7191
Toyo Denki Seizo,
Western Graphtec FD5211, FP52Oi, FP530,. FP5303, GP9001. GP9O11, GP9111, GP9411, MP2000, MP2300, MP3100. MP3200, MP3300, WX4671


GML Protocol Documentation is now availible.

Misc Links

NOAA Ship Discoverer apparently has two modified Zeta 926 plotters on board. It appears that it is used to plot sonar data from the SEABEAM swath sonar. The pen change mechanism will not work reliably on a boat, plane, or similar environment; these two plotters were modified for shipboard use.


Mail from Alan Bradley

Here is a very informative piece of mail I received from a former zeta employee:

Date: Fri, 06 Dec 2002 14:50:17 +0000
Subject: z924 plotters


I have read, with interest, your write up on the Bruning Zeta 924 Pen 
Plotter. I was, in the mid-eighties, a field service engineer for Nicolet 
Zeta  in the UK . I saw the first of the Zeta 8 pen range, (and their 
previous incarnations), right the way through to the prototype Vinyl cutter 
plotter in the early nineties. (All of this information is from memory so if 
I make any mistakes please be gentle with me !).

The Range

The range was, in historical order, as follows:-

Zeta8: - which was the basic design for all that came after it.

Zeta887 :- a Z8 plotter with a 3270 IBM protocol converter built into 
in,(called the "87 option" in the UK).These are easily recognizable by the 
BNC connector in the back of it.

Z824 & 836 :- a stretched Z8 ,(being 24 & 36" wide respectively).

Z824C/S & 836C/S : As above, but with the c/s (Cut Sheet) option.

Z8A:- The "Updated look" version,(New "dead flesh" front panel, updated 
firmware and abit faster).

Z924 & 936 :- The updated look gets to the larger format machines...

Z924C/S & 936C/S :- Updated Cut Sheet machines.

Cutter Plotter :- saw the prototype of this just before I was made 

Connection Options

The machines were fitted as standard with 2 RS-232 ports , one male, one 

Options wise the all the machines could be fitted with the 87 option, (the 
IBM Protocol converter bd & connector), or the IEEE-488 interface.

Z824/836 & 924/936's could be fitted with the C/S, Cut Sheet, option (with 
updated firmware).

Z824/836 & 924/936's could also be put on a "motorized stand", which was a 
plotter stand with optically controlled paper take-up, on roll feed paper. I 
know this isn't a connection option but I thought I'd add it for 
complete-ness sake.

Firmware Options

Early versions ('82-85),of the Z8 series would accept GML,(Graphics Machine 
Language), HPGL ,(Hewlett-Packards Graphics Language) & Calcomp 960 
Emulation . Later versions,('85-92), had IBM 3270, Tektronix and an 80 or 
132 column line printer added.

Switch Settings

The switch settings that you have on your site should work for most of the 
machines in HPGL. The only major things that I remember is to use a 
null-modem cable  and to make sure that the Online Switch,(SW02, Dip 02), is 
set to online.
(I think I have a service manual somewhere in the loft. I'll have to 


The cabling section looks OK. The only cabling I remember was the null modem 
connections. They are:-

25pin (plotter)		25pin(PC)
2                           3
3                           2
4                           5
6                           20
20                          6

PMS Codes

The PMS codes,(and there entry), made perfect sense to me...but then this was 
my first job and I didn't know any better. PMS code 23 should work with a 
straight through cable connecting the male & female RS-232 ports together. 
(PMS 23 sends one half of the test pattern out of the male port and into the 
female, then sends the other half out of the female and into the male.)


The main software that was used with the plotters were:

AutoCAD release 10 - @14 (I think the drivers were shipped with the 
software) made by AutoDesk

SASGraph  (mainly used with 87 optioned machines on IBM mainframes) made by 
SAS Software.

Techie Stuff

Early versions of the Z8 had a switching power supply as the PSU. These were 
extremely volatile.(So much so that the first models we had in the UK used 
to be turned on with a broom handle while you were standing in another 
room!!!) Later versions had a hybrid PSU in them which were not so prone to 
	There was a problem with the +12v coming up quicker than the +5v on the 
PSU's. This caused +12v to hack along the +5v line and blow the EPROMs and 
the processers, thus making them very expensive fuses. This was fixed with a 
5.6v zener diode being placed on the +12v as a voltage clamp.(Used to blow 
the zener instead of the PROMS & Processors). The symptoms of this were all 
the front panel lights on and the buzzer sounding continuously at power up.
	If no data is coming through one or other of the RS-232 Ports run PMS 23 to 
determine which port is failing. Look for a set of ic's in the top left hand 
corner, (near the RS-232 ports), which the numbers 1488, 1489 on them. These 
are the RS-232 buffer chips and, at a guess, they may be blown.
	Error 81 (buffer over-run) was normally caused by parity being incorrect. 
Try none/mark first.
         Printer emulation mode is quite handy for finding out what data is 
being sent to the plotter.(very good for finding the cause of error 86).

I can't think of anything else. I hope this has been informative and of help 
to you.

Alan Bradley

Want Ads

80 rolls of 36" paper

From: Jonathan Jones 

I came across your site while doing a search for 'Zeta plotter' and I was
wondering if you could help me.  Do you know of anyone who has a 36" Zeta
plotter who would be interested in about 80 rolls of acetate, plain and
glazed paper?  I once had a Zeta 836 plotter which eventually died and I
was left with loads of paper and many, many pens (both for paper and
film).  I live in the Wash. DC  metro area and would love to part with all
of it.  I will consider any offer.

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