What good is an HP plotter?

[Massimo Gnerucci]

(05-09-2018 12:17 PM)Robert VM Wrote:  Inkscape (on linux) can output HPGL.

Inkscape can save a HPGL file on Windows too.

[Sylvain Cote]

(05-07-2018 02:07 PM)Dan Grelinger Wrote:  

(05-07-2018 12:42 PM)Mike (Stgt) Wrote:  Could you please give full particulars what an HP-41C/CV/CX could do what an HP-71B (for example) can't?

Ciao.....Mike

I am not familiar with the HP-71B, so am unable to do a comparison.

It may be that my comment was misunderstood. If using an HP-41C, there are things that can be done with the 7470A that cannot be done in any other way (with an HP-41C, i.e. color plotting and printing). If using an HP-71B, I do not know what can be done.

Dan,

The HP-7470A plotter only understand Hewlett-Packard Graphic Language (HP-GL).

The HP-82184A Plotter module gives you high level commands that it translate into lower level HP-GL commands.

First, you must know that the HP-7470A plotter support these paper format: US Letter (257.5 mm x 191.25 mm) and Metric A4 (272.5 mm x 191.25 mm)

Second, plotter values are in milimeters multiplied by 40, ex.: 72.5 mm translate into 72.5 x 40 = 2900

Example #1 : Initialize plotter module buffer

Code:

PINIT

translates into the following HP-GL commands

Code:

DF;                     // set default value
DI;                     // absolute direction instruction, same as DI 1,0
SP1;                    // select pen 1
OP;                     // output P1 and P2, plotter response : 250,279,10250,7479 (values are in milimeters multiplied by 40)
OE;                     // output error, plotter response : 0
IW250,279,10250,7479;   // input window set to what was received by the previous OP command response
OA;                     // output actual position, plotter response : 0,0,0 meaning X=0, Y=0  (relative to the new input window) and pen is up

Example #2 : set new graphic limit to (Xmin=72.5mm, Ymin=62mm) and (Xmax=172.5mm, Ymax=129mm)

Code:

 72.5 ENTER 
172.5 ENTER 
 62   ENTER 
129   LIMIT

translates into the following HP-GL commands

Code:

IP2900,2480,6900,5160;  // input P1 & P2, set scaling points 72.5x40, 62x40, 172.5x40, 129x40
OE;                     // output error, plotter response : 0
DF;                     // set default value
DI;                     // absolute direction instruction, same as DI 1,0
SP1;                    // select pen 1
OP;                     // output P1 and P2, plotter response : 2900,2480,6900,5160 (72.5, 62, 172.5, 129)
OE;                     // output error, plotter response : 0
IW2900,2480,6900,5160;  // set input window to 72.5x40, 62x40, 172.5x40, 129x40
OA;                     // output actual position, plotter response : 0,0,0 meaning X=0, Y=0  (relative to the new input window) and pen is up

Example #3 : draw a frame within the new graphic limits, strangely the plotter module is using the limit values but is drawing using absolute values

Code:

FRAME

translates into the following HP-GL commands

Code:

PU;                     // pen up
PA2900,2480;            // move pen to the lower corner (Xmin, Ymin) (2900, 2480)  (72.5x40,  62x40)
PD;                     // pen down
PA2900,5160,6900,5160,6900,2480,2900,2480;  // draw frame using plot absolute
                        // move pen to the next corner  (Xmin, Ymax) (2900, 5160)  (72.5x40, 129x40)
                        // move pen to the next corner  (Xmax, Ymax) (6900, 5160) (172.5x40, 129x40)
                        // move pen to the next corner  (Xmax, Ymin) (6900, 2480) (172.5x40,  62x40)
                        // move pen to the next corner  (Xmin, Ymin) (2900, 2480) ( 72.5x40,  62x40)
PU;                     // pen up
OE;                     // output error, plotter response : 0
OA;                     // output actual position, plotter response : 2900,2480,0 meaning X=72.5 mm, Y=62 mm (absolute values) and pen is up

A small introduction to the HP-GL world

Sylvain

[Dan Grelinger]

Thanks Sylvain,

I have an Opt. 3 HP7470A Plotter with HP-41, HP-IL module and Plotter module to make some plots. The geek in me is very happy watching this work. I like seeing my HP-41CX driving a 'big rig' so to speak. I have not dived into HP GL, but know that it exists.

By the way, did you ever figure out what the bug was in the 41CL that interfered with one of the Plotter functions? I don't remember the details, they are lost in my pile of old emails.

[Jurgen Keller]

(05-11-2018 09:21 PM)Dan Grelinger Wrote:  ...
I like seeing my HP-41CX driving a 'big rig' so to speak. I have not dived into HP GL, but know that it exists.
...

One of the largest plotter an HP-41 (or HP-71, HP-75) can drive is probably the HP 7580. It has an HP-IB interface. I once wanted to buy one but in the end I didn't due to an out-of-space exception ;-)

[Sylvain Cote]

(05-11-2018 09:21 PM)Dan Grelinger Wrote:  I have an Opt. 3 HP7470A Plotter with HP-41, HP-IL module and Plotter module to make some plots.
The geek in me is very happy watching this work. I like seeing my HP-41CX driving a 'big rig' so to speak.

Understand completely.

(05-11-2018 09:21 PM)Dan Grelinger Wrote:  I have not dived into HP GL, but know that it exists.

The HP-41 is not really equipped to handle a lot of string, but the HP-75C/D and HP-71B are.
When I bought my first HP-75C in 1983, one of the first thing I did was to develop BASIC programs to control my HP-7470A and to do that I had to learned HP-GL.

(05-11-2018 09:21 PM)Dan Grelinger Wrote:  By the way, did you ever figure out what the bug was in the 41CL that interfered with one of the Plotter functions? I don't remember the details, they are lost in my pile of old emails.

Unfortunately, I never had the time to finish the investigation, other things got in the way.
I need to do and/or finish the following projects before going back to it:

• 41CL Update Manual (way overdue)
• HP-IL Compendium (in progress, need to be done by September for HHC2018)
• HP-71B Compendium Update (not started yet, need to be done by September for HHC2018)
• HP-75C/D Compendium
• HP-41C Compendium
  

Sylvain

[vassilisprevelakis]

(05-07-2018 02:15 PM)Maximilian Hohmann Wrote:  But you need an HP-IL to either RS232 or HPIB (depending on what your plotter needs, mine has HPIB) interface. Which will cost a multiple of what those plotters sell at flea markets for - if you can find one at all. With such an interface the HP-71B can send all HPGL commands to the plotter which the plotter is capable of understanding, just like you would send characters to a printer.

Actually you can use this HP-IB Arduino Converter to connect to the HP-IB plotter.
If you combine this with the HPIL PIL-Box module you can do the transfer with new equipment.

Note also that you can send a ready made file to the plotter (like a printer), so you can prepare the file on the HP-71B emulator and then send it to the plotter.

**vp
http://www.series80.org

[Garth Wilson]

I'd like to have the 7470 or 7475, as long as I could get pens for it. I would use it to draw graphs with my 41 or 71. These plotters have a lot of built-in functions, offloading some of that from the calculator, like calculating the individual characters' segments for labels, and labeling in different directions IIRC. My employer had one in a back room of a facility I seldom visited, and I said, "If you ever decide to get rid of that, I'd like to have it." Well, I guess they forgot, and when they moved, I think it probably went to E-waste. What a shame.

At my last previous place of work, in the late 1980's, we used one to draw printed circuit boards from the CAD. This was back when you had to do the artwork (either manually taped, or drawn on your plotter), take those films to the graphic-arts house to have them reduce them to the actual size to make the PC boards, and then drive the reduced films to the board house. Later the board houses had their own BBSs (remember those?) and we could send the files over the phone lines without leaving the office. After that, there was the internet, although still on dial-up before we had DSL or faster services.

[Maximilian Hohmann]

Hello!

(06-05-2018 08:55 AM)Garth Wilson Wrote:  I'd like to have the 7470 or 7475, as long as I could get pens for it.

Pens should be the least of worries. They are still sold new by HP and there always have been plenty of third party suppliers. When I still used my 9872C flatbed plotter I mainly used third party ballpoint pens which take standard fountain pen refills. That cut the cost of plotting down to 1/10 compared to using the original HP felt tip pens. I even have a full set of compatible Rotring "Rapidograph" drawing pens for China ink used for technical drawings. They produced excellent plots but had the usual problem of these pens of drying out quickly when not in use followed by y tedious job of getting them working again.

Regards
Max

[Massimo Gnerucci]

(06-05-2018 11:30 AM)Maximilian Hohmann Wrote:  Rotring "Rapidograph" drawing pens for China ink used for technical drawings. They produced excellent plots but had the usual problem of these pens of drying out quickly when not in use followed by y tedious job of getting them working again.

Oh if I know that!
Wash and rinse, wash and rinse...

[Maximilian Hohmann]

Hello!

(06-05-2018 11:34 AM)Massimo Gnerucci Wrote:  Oh if I know that!
Wash and rinse, wash and rinse...

I briefly even did this for a living. In the very early 80ies I had a student job in a civil engineering firm (specialising in traffic planning/engineering). During the day we would assist in screening and entering data and during the night one of us students was tasked with plotting the results. Three or four plotters were connected to HP desktop calculators and one of them would constantly need attentention: Replacing paper, replacing pens, cleaning clogged/dried pens, restarting a hung computer or program, manually keeping track of the jobs completed and the ones left to do and so on. Sometimes this lasted until 7 in the morning when the first regular workers would claim their computer again for their day work and there wasn't even time to go home for a quick breakfast before lectures at university started at 8... Since then I like collecting that kind of stuff, but I will never ever again use a 1980ies calculator or plotter or printer to do real work. No way. Ever

Regards
Max

[Massimo Gnerucci]

(06-05-2018 12:22 PM)Maximilian Hohmann Wrote:  Hello!

(06-05-2018 11:34 AM)Massimo Gnerucci Wrote:  Oh if I know that!
Wash and rinse, wash and rinse...

I briefly even did this for a living. In the very early 80ies I had a student job in a civil engineering firm (specialising in traffic planning/engineering). During the day we would assist in screening and entering data and during the night one of us students was tasked with plotting the results. Three or four plotters were connected to HP desktop calculators and one of them would constantly need attentention: Replacing paper, replacing pens, cleaning clogged/dried pens, restarting a hung computer or program, manually keeping track of the jobs completed and the ones left to do and so on. Sometimes this lasted until 7 in the morning when the first regular workers would claim their computer again for their day work and there wasn't even time to go home for a quick breakfast before lectures at university started at 8... Since then I like collecting that kind of stuff, but I will never ever again use a 1980ies calculator or plotter or printer to do real work. No way. Ever

Regards
Max

Hi Max!

I used Rapidographs mostly for personal sketches/high school classwork drawings.
I had quite a set of about 10 pens in different sizes; can't remember how many .1/.15 pens had to trash and replace due to dried ink. The thinnest ones had their inner wire bended so easily...

Regarding paleo-computing I, too, cut my teeth on night shifts, transferring newspapers articles from Apple ]['s 5.25" to 8" floppies. Wouldn't do it again nowadays...

Ciao (da un altro) Max

[TomC]

Pens new from HP???

(06-05-2018 11:30 AM)Maximilian Hohmann Wrote:  Hello!

(06-05-2018 08:55 AM)Garth Wilson Wrote:  I'd like to have the 7470 or 7475, as long as I could get pens for it.

Pens should be the least of worries. They are still sold new by HP and there always have been plenty of third party suppliers. When I still used my 9872C flatbed plotter I mainly used third party ballpoint pens which take standard fountain pen refills. That cut the cost of plotting down to 1/10 compared to using the original HP felt tip pens. I even have a full set of compatible Rotring "Rapidograph" drawing pens for China ink used for technical drawings. They produced excellent plots but had the usual problem of these pens of drying out quickly when not in use followed by y tedious job of getting them working again.

Regards
Max

[Maximilian Hohmann]

(06-05-2018 03:05 PM)TomC Wrote:  Pens new from HP???

At least they are sold as "HP plotter pens", e.g. here: https://www.draftingsteals.com/catalog-p...-pens.html
I don't know the associated legal issues in the United States, but around here you could not sell them as "HP pens" if they were not from HP.

[Garth Wilson]

Ah yes, I do remember now the maintenance they had to do with the pens used for the PC boards, pens that had different tip diameters and used something like India ink. They were always cleaning them. I do not remember them having any trouble though with the colored felt-tip pens used for doing charts and other things.

[Maximilian Hohmann]

(06-05-2018 06:09 PM)Garth Wilson Wrote:  I do not remember them having any trouble though with the colored felt-tip pens used for doing charts and other things.

The trouble with these was that eventually - rather earlier than later - they ran out of ink. So your plotter spent the best part of an hour painting a beautiful chart and two minutes before finishing it, the blue pen runs dry. You throw the chart away, replace the blue pen and start over. Only this time, it is the green pen which gives up after 10 minutes... And other than with modern ink-jet or laser printers, which know how much ink/toner they have left, a plotter has no idea how long it's pens are going to last.

[Garth Wilson]

(06-05-2018 06:40 PM)Maximilian Hohmann Wrote:  

(06-05-2018 06:09 PM)Garth Wilson Wrote:  I do not remember them having any trouble though with the colored felt-tip pens used for doing charts and other things.

The trouble with these was that eventually - rather earlier than later - they ran out of ink. So your plotter spent the best part of an hour painting a beautiful chart and two minutes before finishing it, the blue pen runs dry. You throw the chart away, replace the blue pen and start over. Only this time, it is the green pen which gives up after 10 minutes... And other than with modern ink-jet or laser printers, which know how much ink/toner they have left, a plotter has no idea how long it's pens are going to last.

I was not personally involved in the plotter use where I worked. I only observed from a distance. At the job where I saw the charts being made constantly from vector network analyzers, I imagine the pens were replaced regularly, together, so you don't have the situation you describe. That plotter was going continuously, only a couple of workbenches over, and I don't remember hearing any complaints. Of course, if you're doing business-type charts where you're filling in wide bars on bar graphs with solid color, yeah, the pens will run dry a lot faster.

[Maximilian Hohmann]

(06-05-2018 06:46 PM)Garth Wilson Wrote:  At the job where I saw the charts being made constantly from vector network analyzers...

In the days when I used a vector network analyser (1989-92) plotters were already a thing of the past. We had laser printers then which would print the chart in a few seconds and for the important stuff (presentations!) a color-sublimation printer which was able to print beautiful A3 sized images on paper or transparency within a few minutes. Very expensive and an incredible waste of plastic foil.

But you are right, for pure line charts the HP felt tip pens last very long. But only if you take them out of the plotter after use and put the caps back on - the spring loaded caps inside the plotter don't seal them properly!

[Garth Wilson]

(06-05-2018 07:42 PM)Maximilian Hohmann Wrote:  

(06-05-2018 06:46 PM)Garth Wilson Wrote:  At the job where I saw the charts being made constantly from vector network analyzers...

In the days when I used a vector network analyser (1989-92) plotters were already a thing of the past. We had laser printers then which would print the chart in a few seconds and for the important stuff (presentations!) a color-sublimation printer which was able to print beautiful A3 sized images on paper or transparency within a few minutes. Very expensive and an incredible waste of plastic foil.

At the place of work where a couple of the engineers were always using the plotters to make the charts from vector network analyzers, it was 1984-5. I don't know if laser printers existed yet, but although we had about 100,000 of equipment per engineer in the lab, the only printers we had were still dot-matrix-impact, and much slower than the ones that were out just a few years later. We do have a color laser printer at home, and we've had a couple of inkjet printers, and they have been constant trouble and very expensive to feed and maintain. A real pain. They also couldn't do B size (11x17") like the 7475 can. I still use an old dot-matrix impact printer for program listing where I want fanfold paper with no page breaks, and it has been trouble-free.

Quote:But you are right, for pure line charts the HP felt tip pens last very long. But only if you take them out of the plotter after use and put the caps back on - the spring loaded caps inside the plotter don't seal them properly!

That makes sense.

In the later 1990's, we had a plotter that we used for D (24"x36") and E-size (36"x48") drawings, which used mechanical-pencil lead. It kept feeding the lead to the proper length, and sensed when there wasn't enough left, and it disposed of the short piece and picked up the next piece, automatically. The lead of course never dries out, nor does it skip if you go too fast, nor does it soak into the paper if it's left down too long.