HP 7475A Plotter and HPGL Demo 

YAY IT ARRIVED

"-I'm a time traveller! And where I come from, we have one-armed robots that draws spaceplanes! Spaceplanes that actually flies, fixes space telescopes in orbit, and lands on runways! -Wow! and how far in the future do you comes from? a century or what? -Sorry, but I'm coming from 40 years in the past..." :'(

Years ago at Boeing, we'd use HPGL as a graphics interchange language if nothing else like IGES output was available. Virtually all the systems had the ability to plot in HPGL if nothing else. I wrote many a HPGL to X and X to HPGL translation programs to transfer graphics between different engineering groups around Boeing during that time frame. It was a lot of fun.

The innovation that made this series of plotters great was to move the paper instead of the whole pen carriage, and to do it without losing accurate paper registration. The system was called LIPS - Low Inertia Plotting System. The first plotter to use this was the two-pen 7470, codenamed Sweetlips. I think the 7475 may have been called Hotlips internally. The final desktop model, which was astonishingly fast, was the 7550 which featured automatic paper feed. Moving the paper was achieved by using rollers with gritty surfaces, or grit wheels. Finding a way to make the grit wheels in such a way that they would make tiny indentations in the paper that would reliably re-engage with the grit particles that made them was the key to success. If you look at the edges of a sheet that has been plotted you can see the tiny tracks of pits that the grit wheels have made.

The engineering firm I worked at in the late 80's had a pair of 7475A plotters that ran 12-14 hours per day, 6 days a week cranking out electrical schematics on 11x17 paper. The techs that ran the plotters could switch out paper and pens in a hurry. The constant click / clack of the plotters was annoying until you realized that was the sound of progress. There was a third plotter plus more spare parts to keep everything moving. The 7475A is an amazing device. We even worked on optimizing the movement of the paper and pens to save precious seconds on each drawings.

I remember seeing someone pull one of these out of a storage room, plug it in, press the Confidence Test button and have it work perfectly despite having been there for 15 years or so. Even the pens still worked fine. Meanwhile modern HP inkjets will demand a new set of ink cartridges to print anything if you leave them idle for 15 days.

When R&D has more than marketing, you can tell it's really just a demo. Or to paraphrase the old proverb: a figure lies more than a thousand words.

Amazing machine that brings back good memories. I used it a lot back in the 80’s to print transparent slides in color to present on an overhead projector. Remember those?

Oh the days of my glorious youth in the Engineering Department doing our first CAD drawings...

More than 40 yrs ago I had a summer job working in a university physics lab. They had a full complement of HP gear - 9845 computers, 85 computers, plotters, test gear, etc. The sounds of the plotter running take me back to those days.

This brings back MEMORIES! Back in the late '90s, I spent 3 of my 4 High School years taking the entirety of the Mechanical Drafting vocational courses (intro and full course) at our county's Vo-Tech school. Our instructor was retired from Black & Veatch, and he was very old school. For every single assignment, we were required to first do the drawing with board & paper, then in AutoCAD (DOS based, on old 486s), and then plot it out using a large free-standing HP Plotter (way bigger than this one), hooked up to a floppy disk plot station. We had both multi-weight pen sets, as well as colored pen sets, and we'd have to select and set up the pen arrangements to match the drawing style and specifications required for that assignment. I was the first, and still the only, Junior to complete the full Course. Unlike the other students, who would just start the job and leave - I used to LOVE standing there, watching the plotter do the WHOLE drawing, right before my eyes, with inhuman speed and precision that I could only dream of.

Brings back memories of 1986 for me. Our group used this plotter controlled by a HP85 to create overlays for an LED alarm matrix on a Granger telemetry system ( put a label on each LED so the controllers could see what the alarm was). We used the liquid ink pens and plotted onto clear Mylar. I still feel guilty about the numerous times I left the pen in the carousel after a plot and the ink dried in the nib. First time I’d ever seen an ultrasonic cleaner - a colleague got one and it would clean the pen in 30 minutes or so so that was a relief. As a funny aside, he later took the ultrasonic cleaner home as he had heard they could clean jewellery. His wife’s friends all brought their rings over too so he put them all in it and turned it on. 30 minutes later there were a bunch of very clean rings, but sadly a slurry of gemstones at the bottom of the bowl which had been shaken out of every ring. That story still makes me laugh 35 years on.

Now Chrono Trigger jazz? Of all the reasons I watch this channel, I wasn't expecting jazz covers of excellent game music to be one of them. A+ selections, truly.

I worked in the early 90s with such Plotters a lot, to plot electrical diagrams out - I never realized how much I missed those plotters, until I saw this video... it has something relaxing, watching them plotting something out...

Used these for decades. The company I work for mainly uses Hewlett Packard/Agilent..etc etc equipment. In the eighties all the network analysers and spectrum analysers used these to hard copy test results. They were utterly reliable. What stopped us using them was the difficulty in ensuring pen replacements in the end.

This is absolutely mesmerizing. In an era of inkjet printers, I truly admire the quality mechanical engineering that went into making this device. I have to admit, a part of me would also love to see a 3D printed plotter arm that looks like a baby's hand :P

An HPGL Etch-a Sketch would make for a mesmerising showpiece!

I still have this plotter after saving it from the trash at the engineering company I worked at in about 1995. It was later caught in a flood in about 2000, but after cleaning out the mud and drying it out, the demo still ran perfectly. It isn't intact though... In about 1990 I sawed the case to make a gap between the bed and the pen turret so that we could use the much longer pens, and pens with metal nibs and finer points for cleaner plots. A fantastic machine, and I'm thinking now a real-time plot from my arduino weather station would be fun! Thanks for showing this off!

Awesome! As a kid, I would get the half-empty stubby pens from my dad ...

I remember a family friend printing what I’m pretty sure was the exact same drawing (the space shuttle) out for me on a plotter like that one. It was the most fascinating thing I’d ever seen at 7 years old and very likely helped begin what became a lifetime love for and eventual career in computers and programming.

I love watching pen plotters do their stuff! Especially with AutoCAD drawings!

I still have one of these. I used to create PCB's with it. Like around 10 years ago.

I still have one of these hiding in my computer room, and an assortment of pens still in their sealed bags. Sadly it hasn't seen any action in many many years. Used to draw PCB layouts on mylar film.

Wow, that brings back memories! I was a technical support engineer at HP San Diego Division from 1985-1988, supporting all plotters - flatbed electrostatic flatbeds like the 7225 you mentioned, desktops like this one, and drafting plotters. When I first got there, I decided that a good way to thoroughly learn the way a plotter works was to build one. So every day on my way to the lunchroom I would pass by the bins of rejected parts and pick out parts that would still function (rejected for cosmetic reasons or something), and I gradually built my own 7470A (similar to this one but with only two pens instead of a carousel) for free!

Glad you could put it to use ! It was just collecting dust for the past few years, since other projects got in the way.

in the 80's when i was training to be an engineer, part of my job was 2 afternoons in the "plotter room" maintaining and running the plotter for the highway design department for a local authority, the plotter used paper with paper up to 2m wide, regularly pens would run out mid print or jam etc, and i would have to fix it, and try to sort the plot to continue without restarting the whole plot. it was so stressful, and ou could not take your eyes of the plot at all ! watching the second half, omg the serial instruction, i spent many an our fixing our senior engineers Plans with command like this, and it would always be our error if it turned out wrong !

Ah, the good old times seeing the same old Autocad demo at every other booth at CeBIT early 90ies and watching the plotters in awe drawing them all day...

Also that chrono trigger jazz piece is awesome. I love it

So funny to see that! Hearing the sounds brings up memories from more than 30 years ago, as I was doing my engineering diploma. Part of that was to write a plotter program for exactly the HP 7475A for measuring results diagrams from the High-voltage lab in my university.

Great, in 1979 I wrote a program for HP 9820 and HP plotter. It was a simulator for a photolithographic projector. At our Uni-Department, Microwave hybrid integrated circuits were designed. The projector did not use a photo mask, but an adjustable slit. The circuit itself was created by gradual illumination through this slit, which moved, changed length and width, and also rotated, in the range of micrometers. The calculation and programming of the projector slot movement was done manually. If an error occurred, despite a thorough code check, faulty ICs were made. The software simulator imported the data for the projector, and plotted the connection of the hybrid circuit at the selected scale on the plotter.

The slowest, but most pleasing way to print some graphs.

My 7550A has been stored in my Sea Container for over 20 years, not even packed in protective plastic, dusted it off, turned it on and ran the demo - no problems! Had many sealed Pens but pretty much dried out after sitting in the Container over many Aussie summers. Read a suggestion using Sharpie ink and removing the felt pen by simply pulling it out, using an allen key to push the cap out, installing the Sharpie ink (trimmed to size) and works just fine! Now installing XP on an old desktop as that was the last OS that supported the plotter (serial port) so can just transfer files to that platform for printing!! Soon be plotting Circuit Diagrams again with an entertainment value that ink-jet printers could only dream about!! And seeing the (once treasured, pray again from Nov 2024) "Made in U.S.A." on the printer and all circuit boards. If it was HP, DEC, Honeywell, Foxboro and other great companies, "Made in USA" was a guarantee of fantastic Engineering and Quality! President Trump, Make America (And the Western World) Great Again!!

Watching a plotter doing its thing never gets old, that's why I have a few in my collection. The HP models I have are 7470A, 7475A (1 x HPIB, 1 x RS-232), 9872A, 9872B. Only the 9872A is non-functional. Back in the 80's we used Houston Instruments plotters to prepare x2 photo ready plots on mylar of our PCB artworks, this before transferring Gerber files to the PCB manufacturer was a thing.

Nice seeing one of those old plotters in operation. I didn't know about the built-in test program. When I used to work on the software for a real-time data collection and analysis program at a market research company there were many 7470 and some 7475 plotters around. I worked on the code that generated the HPGL code to draw graphs of the collected data that the researchers used in their reports to the clients. I still have a 7475 plotter. It originally had an HPIB interface but I paid HP to change it to serial. I have the manual for it along with the pen carriers for felt pens as well as the one for ink pens.

Loved this one. Used it to plot PERT diagrams for building the ETA-10 back in the day when “supercomputers” were a thing. Many plots on vellum and then creating a mosaic for a master blueprint diagram that covered most of the conference room wall. Good memories.

Trying to get some fresh plotter pens out of Hughes Aircraft stationery stores was always like pulling teeth, haha… sez grandpa me. Thank you Marc.

We use to use the HP plotters on velium and rubylith, to print thin and thick film microelectronic circuit designs. We would then use the developed photo-etched aluminum screens to print the circuits on alumina or silicon substrate, and then bake, and populate the hybrid circuit! Fun times!

My job in high school was working in a small warehouse for a plotter supply company. Company was based out of CA but maintained a small office with 1 sales person, a secretary and me part time to do shipping and receiving. We fulfilled small orders of pens, paper, etc destined to customers in our local area. I didn't actually see a plotter in action until several years later when I had an HP DraftMaster at my disposal 1st job out of college.

Brings back memories of my start in architecture

Thanks for reminding me of how old I am once again.

Watching (and listening to) this thing run, especially the solid fill at 5:35 getting faster and faster in the corner, reminds me of a modern 3D printer in operation. We had a couple of pen plotters in the drafting room at school, which were later replaced by wide-format inkjet printers. The accuracy on these pen plotters is impressive, especially almost 40 years later!

Take me back to the 80’s! Lockheed in Sunnyvale had tons of HP products

I missed out on plotters in my life - I used some early terminal printers and daisy wheel (I think that one was a typewriter with an interface so you could hook it up to a computer), obviously dot matrix, thermal, ink jet and laser, but plotters passed me by - really great to see one working, cheers Marc.

Good Lord, I haven't seen that demo for YEARS.

Nice to see another one still being alive. I have a DEC branded one. I used you pen repair video to rejuvenate the dried out ones i had.

The sound of plotters doing their thing always makes me stupid happy. Its soooooo cool to hear the mechanics and fast pace processing!

Back in the late 80s, I had a summer internship at in the IT Department of the solid rocket plant of the Chemical Systems Division of United Technologies out in the Coyote Canyon between San Jose and Morgan Hill going through all the departments. This meant I learned all about turning punched cards into tapes, spooling labor report jobs to the IBM mainframe back in Hartford, and handling the wicked bursting and decollating machines. The engineering team had a VAX, so I got some time commenting on rocket simulation code. When I got to the IT management team, they had a single IBM PC hooked up to a 7475 plotter. I could already use a spreadsheet (Lotus 1-2-3) and learned Harvard Graphics to make IT department presentation so I had the PC to myself. The management team wanted a custom formatted graph so I sat down with the HP-GL manual and coded it up for them. They loved it and I wouldn't be half surprised if they kept using it until the plant closed down. The only problem was that the PC was next to the bull pen of IBM mainframe programmers who all smoked like chimneys at their desks (in a rocket plant!) so my closed reeked of stale cigarettes.

The 7440A ColorPro is a very similar plotter which only supports one sheet size. It only had two servos, one for X and the other for Y; pen selection was done by pulling in a clutch which would allow the Y-axis servo to turn the carousel. It actually pulled the sheet along while changing pens!

Love the jazzversion of Chrono Trigger, quite unexpected.

As a young twenty something I remember heating up the soldering iron to modify an IBM PC serial cable to the pinout requirements of a brand new HP 7475A.

the classic autocad space shuttle! it's like the Utah Teapot of plotter art

This takes me back to 1977 (different model), and plotting the cutting swing (in real time) of an American dredge on the coast of Saudi Arabia, in the Kafji area which featured in the war of 1991. I was an employee of a British survey company which was called in to do a job that the Americans had not planned for adequately. The good ole boys had thought that they could spot survey marks in the manner of those on levies in the southern states of the US. The irony was that us Brits were using US made gear which was on the black-list and supposed to be embargoed by the Saudi government (Israel).

I had a 7550. I would print things for my kids color. They liked watching the plotter draw more than coloring the pictures.

I can totally see hacking this into a 2-axis milling/drilling machine for small parts/PCBs, as well as keeping the pens for when someone needs to print out a schematic or blueprint. Happiness. 😍

I actually wrote a compiler to translate Poscscript to HPGL to plot phylogenetic analysis cladograms in color on an old HP pen plotter. Probably in 1994? The compiler was written in Postscript and would run in ghostscript, or in a Laserjet with a bidirectional parallel port to output the HPGL.

I've actually seen this demo live! Had one of these come through at a previous job, and had a set of markers to load in it. Was an HPIB version, and didn't have the hardware to run it off a computer, but that demo makes me smile every time as I never knew plotters like this existed at the time. Thanks for posting this!

I know it's just X and Y stepper motors controlling the arm and paper, but man, I'm so impressed by the resolution from this 1983 machine! It's also very fast!

This background music is forever etched into my brain and plays randomly at any moment.

Nearly 20 years someone gave me a Graphtec MP4200 as present. Some days ago I grabbed him again and did some videos about plotting. Really really fun such a device.

Back in the 80s when I was a kid, my friend's dad had a tabletop pen plotter. The pen moved on X and Y axes and the paper remained still. Was such a trip to watch!

You made me want to pull mine out of storage and give it a try. Excellent video. Many thanks.

That sound... I used one of those as part of my first engineering job in the early 90's. The other people in the office hated it, lol!

That is pretty darn impressive even today

Your channel made me also a fan of old HP equipment and I am glad for that. I now own two HP devices and I hope to add more to my workbench. Thank you, Marc!

It’s so precise and no movement is wasted or extra. It’s like watching my 3D printer but at 100x speed, and the algorithm for making shapes seems more efficient.

I have a HP 7221T flatbed plotter (minus the auto paper advance/cutter, which essentially makes it a 7221C) that I most often use to make prototype PC boards. Still works like a champ. The 1983 HP catalog states the retail price of a 7221C was 5800 USD.

I love the jazz version of the Chrono Trigger music!

I used to use one of those to print out PCB designs for home made photo etch PCBs. The plotter was much better than a raster laser printer or ink jet as it was a solid line from pad to pad, so ideal for PCB traces.

I have a "Houston Instruments HI 1117" that i use regularly (3 or 4 times a year), last time was this morning. It is compatible with HPGL and HP-pens. Using it mostly to print my logo and adress on envelopes. The paper-bed is still on the HI 1117. Also have a HP7580B for big plots and cad drawings. I am using HP ballpoint pens from the end of 1990's. They lasts FOREVER! I think I have used up 2 pens the last 15 years. I use win XP with "WinLINE" HPGL printer drivers for my plotters. Greetings from Sweden.

This video has brought back all of the horrible anxiety of my early days in the CAD Lab at school waiting to be able to plot my project and hoping the guy with the dense hatch patterns doesn't use up all the black pen ink - LOL...

And now I feel really old... I used to use this exact plotter model in my first job. Oh!, memories...

In high school we got a HP plotter, it did D size paper. We had it connected to a Mac Plus and a XT computer with an 8086 and CadKey. I do NOT miss those days, lol. Now I have solidworks 2020 and a Canon Pro-2000. Bit of an upgrade.

This is something I never knew I wanted.

Used to have that plotter about 20 years ago. My Dad was an architect and I worked for him. I used this at home to run test plots for drawing changes before we ran them on the 42” plotter.

I believe this was one of the models where the paper was driven by a pair of wheels with a random rough surface like abrasive paper. The paper was fed from end to end at the start of the plot and after that the bumps on the wheels fell into the pits the wheel had made and so kept in registration. If you look carefully along the left and right margins of the paper you could see the indents. This got over the problem of having to use special fan fold paper with side perforations that was used in the earlier generations.

That unit is in great shape. It’s impressive how long these last with so many moving parts, especially considering what appears to be high acceleration when plotting. I’ve got a couple of the two-pen 7470As and one of them works perfectly. I even bought a digitizing sight that is shown in the HP-87 Plotter ROM manual demonstrating how to digitize an image from a photograph, but I haven’t given that a try yet. I’m not sure if I’ve got the patience or the eyesight required to do that successfully.

Jesus now I know I am getting old. Used one of these A LOT at National Semi as a student engineer to do process charts etc for the fab. In the end I wrote my own HPGL visualiser in C so I could see the plots on screen from the HPGL files as it was a bloody slow plotter. Like all HP kit of that era though it was a beautiful piece of equipment.

9:05 Shnabubula! Excellent choice.

I'm surprised how much high level functions were in the device itself. I would have expected something more like G-code: just line segments and basic curves.

Awesome! I got this plotter as my 15th birthday present! Lots of wonderful memories of using and playing with it.

I still have my HP 7475! all in good shape stored inside for 35 years or so.

Oh the flashbacks... We had a big HP plotter in my high school drafting class. You had to really pay attention when loading large sizes of paper (36"x48") otherwise your drawings would come out crooked. And it's always fun when a pen runs out of ink halfway through the plot.

My first paying programming job was at a small company that did architectural software on HP computers (9845, 9836, 9826), which pretty much supported HP pen plotters out of the box. We had a couple HP 7470s, an HP 7475A, as well as an HP 7585 -- the big A0 chart plotter. I had a lot of fun using them to draw 3D wireframes of home floorplans. And yeah, those things went through pens like candy.

The operation of complex mechanical contrivances give me immense joy.

This is awesome!

Amazing piece of technology

I used to use this printer to graph absorption and emission spectra of fluorescent molecules from an HP diode array spectrometer in a physical chemistry lab I worked in when I was in college. We had a lot of HPIB gear to run our experiments and collect data.

Love the rhythmic counterpoint between the shuttle plotting and the jazz.

Being used to 3d printers, the speed and acceleration of both the head and the paper are quite astonishing!

I remember a big a0 pen plotter where my dad worked in the 80's. It could take up to a day to finish printing. Also the autocad model brings back some memories, they added a fully blown 'complete shuttle on launch platform' in a later version, or it was on the crawler. Can't remember.

That demo brought such a smile to my face. It’s so business! Very PowerPoint! I especially loved how quickly it drew that line graph at the end there. It’s a confident beast!

I used the ibm white label of this plotter for a couple of years at a co-op job in college. We used a dos program called Freelance to make many slide presentations. Hours upon hours spent waiting for these presentations to plot. It’s interesting to see this still going. Amazed that you have working pens!

Awesome! I just picked up a cheap Chinese vinyl cutter, but it talks HPGL over 9600 baud serial, *and* it comes with a pen holder that takes a regular ink refill.

I had an HP 9000 and that exact plotter! Used to draw blueprints - and what a nice job it did, I really miss that set-up,,, had the pen tablet and an external HDD,,, not HP , forget the brand now,, IM or maybe IMM or something like that - Always wanted a 48"+ Roll Paper plotter but big bucks even then,,, so the 7475 worked as the copy shop scaled the prints up !!!!

Yes plz, normal speed video. I find this fascinating to watch, very relaxing.

Man that brings back some memories... my father had one of these, long before we got our first inkjet, and I remember printing out that exact demo picture.

As requested: GOOD SIR I WOULD INDEED LIKE THE FULL REAL TIME VERSION IN A BONUS VIDEO

I've never seen one of these in action. Didn't know it moved the paper and the print head to draw the image. Fascinating. Fun to watch.

That takes me back!

One of the coolest machines ever!