Hello and welcome back. If you follow the channel, you know that I have a thing for the
olden mechanical plotters from Hewlett-Packard, and of course anything vintage HP in general.
Like in this previous episode where I misused an HP 7225A plotter, currently my only working
plotter, to plot an anime picture from my HP-85. It’s a children demo favorite.
I have a few more plotters in the restoration queue, but thanks to viewers Frederik Grufman
from Sweden and Robert Moon locally, I just got a model that I didn’t have,
and on top of that, this one just plain works. So here goes a little demo.
So today we are going to do a quick video about the HP 7475A plotter.
It's no secret to you that I love HP plotters, but this one actually came from viewers.
I had donations from actually two viewers, Robert Moon and Frederik Grufman all the way from Sweden,
that allowed me to assemble that whole system. And from Sweden, I got that incredible box
of HP pens - because of course the bane of these, is that you have to get pens that work. And I
have another video on how to rejuvenate those. But here we go, I'll make a little demo of it.
So to load this one, there is a little line over here. You line up the paper
and you get the little lever down, and off you go. Actually I'll leave that open so you can see.
To fetch a pen, let's fetch pen 3, the red pen. We press 3
It growls, that's normal, gets pen three. And then you can go
to P1, that's the lower left and, P2, making sure you're well centered. Now to get pen
three back in, you do Enter - 3. There you go. On this one, there is a little demo program that's
in it, and to launch it, you turn it off, press P1 - P2, turn it on.
Graphics improves
communication
Oh, my sales are gonna go up!
Just a little bit of sales, but it's going to get better.
And it changed pens. I have to make a little bit bigger so you can see the pen change
And
note that the fill is different on each of the colored bars.
The crosshatch is finer at the bottom than in the middle, and then on the last one it's
not cross hatched. And, oh, darn it, I have to wait until 1982 until my sales start to grow!
So it's doing cross hatches. It has to think a little bit.
And it can even do solid fills. Very nice!
Look at that! Even admin makes some revenues!
Incredible.
And there you go, I think that's a very neat demo: "Graphics improves communication!".
There are several versions of these, including the probably more common HP-IB,
which interfaces better to HP computers of course. But here is the serial version,
and I didn't have to make the cable for it, because Frederik sent it to me
from Sweden! So all you have to do to connect to a modern computer,
is to get this in the right orientation. So you have the same problem as USB. There you go,
and you're connected. And on the computer side of things, there are still a few programs that
support it. This is a DWG TrueView 2013, so an old version of Autocad
that still works with it. And you can plot it, using - I set it up somewhere -
[HP] 7475, there you go. It's not very good at figuring out what to plot, but once you do
that you're fine. And then, the difficulty is to get it to plot in the right colors.
So it's over here, so let me check that I have them correct.
Okay, seems that it retained my previous settings, I just have to swap one pen.
I have to take that little carousel out. And this one should be the yellow. And the yellow
tends to turn into some kind of dark color, but this one is still yellow. Here it has a little
cup, then you put it in there and turn it until it goes [in], and you are done.
Apply to layout and go...
It seems to be happy, grabbed the yellow pen
which is looking more brown than yellow.
The HP 7475 is way faster than my HP 7225, but still.
I’ll speed it up a bit so we can get to the HPGL section before falling asleep.
Yell in the comments if you want the full original speed sequence in a bonus video.
I think that's it, it's done. There you go!
Very well done, HP plotter.
But one of the beauties of this machine is that it speaks HPGL,
so all you need is actually your terminal, and then you can send it graphics commands.
It's a serial terminal connected to the printer. IN, initialize, now we'll have
it identify, OI, see if I'm connected. Yes, it answered 7475A. Let's take pen one, SP1.
Oh, except I have the wrong pen in there. So I do SP0,
and I'll get the pen back in.
Okay try again: SP1. Okay, that's the black pen. So I'm going to set it as 130 max on the X
and 100 max on the Y, which actually should give me a grid that's square. PA10,
100 space. Yeah, so that did work. And over here, well, you can of course draw
lines. But it's a little smarter than this. You can do a label. Label "Hello".
You can hardly see it, but it wrote "hello". Let's make it bigger. SI 0.3 high,
no 0.3 wide 0.45 [high], and let's take another pen
Label...
Ah, now, that's better!
Now we're talking!
And it's actually a typewriter. Awesome! This is a - oh I made a mistake - type T writer.
Let's change directions, DR1,-1. So that will have us go at -45 degrees.
We are going down, look at that!
Okay let's get out of that: Control-C. SP4.
Somewhere there. Circle, 15 units in the radius and 5 degrees in resolution.
And here I chose 5 degree arcs.
Rectangles: this Edge Absolute. So let's see if that works. Okay, that's a rectangle.
But let's do a cross hatch. You have to do Fill Type 4, which is cross hatch.
So hatches lines separated by one unit, and at 45 degree angle.
And now if I do a filled rectangle which is [the] RA command, it should will it with a cross hatch.
Very neat! Let's do a wedge:
diameter 20, goes from 0 to 135 degrees with a 5 degree resolution. See what that does.
It has to think a bit because it's cross hatching a wedge. And that's hard for the poor thing.
And that just does the inside, so I have to do the outside, and the command is
EW for whatever reason. They are all very short mnemonics, but they are not obvious,
you have to look them up. Then that should draw the outside of my wedge. Here we go. We
can do dotted or dashed lines. We're going to do a dash, that's LT, line type 2. LT, there you go.
So
if i do line type with no arguments, we're going to get back to the default.
You can also use the circle command to do hexagons and stuff like that, by just specifying
a large resolution. So it's 60 degrees segments, so that should do an hexagon.
There we go, that's easy. And we store our pen, SP0, and we're done! So you get the idea, right,
it's really really easy to control: you just need a serial connection. So that would be
a real neat project to hook up to an Arduino, and start to do some Arduino art on it. So thanks
again to the viewers Robert Moon and Frederik Grufman, and give a hand to the HP 7475A plotter!