HP-41 draws sine curve


HP-41 draws sine curve







It says you need the plotter module. The plotter module will probably make it easier, but you can do this without it. The plotter just uses HPGL (HP graphics language) which is plain text, so it's basically like you're printing the text data, and the plotter interprets it. "PU" (plain text characters) for example means "pen up." If you have the 82169A HPIL-to-HPIB (GPIB, or IEEE-488) interface converter, you can use the HPIB version of the plotter too, without needing the HPIL option. Alternately, if you have the HP82164A or FSI164A HPIL-to-RS232 interface converter, you could use the RS-232 version of the plotter without the HPIL option. There are lots of ways to skin a cat.


Yes, I know that, but I wanted to keep the movie short; pointing out all options would have been too confusing.

Anyway, when plotting bar code - I suppose this was one of the main applications - the plotter module turns out _very_ handy. I also tried the HP-IB option with my 9872B plotter (this is a real beast). The only difference is that you have to SELECT the plotter manually (use MANIO, then enter the address of the plotter and SELECT). Finally, an unfullfilled dream is to drive a 7580B plotter with an HP-41 ;-)



Nice work Juergen!

I too have been doing similar work, although with the HP48 family and RS232 communication.

[Very nice video production, by the way!]

It is a fascinating 'act' to watch a tiny calculator driving an 'E' size sheet plotter!


Edited: 21 Mar 2010, 11:32 a.m.


Yup, I have all the stuff including the 7470 Opt. 003, although I expect all the pens dried up years ago.


You can still buy suitable new pens, e.g., on eBay ...


You can still buy suitable new pens, e.g., on eBay ...

Thanks, Juergen!

Oh yeah, those were the times ...


Great production Juergen!

Thanks for the Sunday present :)


Very nice to see this in action. It reminds me an article from the December 1982 HP Journal:

Controlling a Graphics Plotter with a Handheld Programmable Calculator,

by Robert M. Miller and Randy A. Coverstone The plotter is the 7470 A. The calculator is the HP-41C.


Hi Jurgen,
many thanks for this beautiful time machine.




Thank you for posting the video, Juergen. It is neat to see the plot of the sine curve with an HP 41.


P.S. Beautiful choice of background music, too.

Edited: 23 Mar 2010, 10:05 p.m.


really cool. I'm still looking for the 7470A Opt 3 (got a 7475 with HP-IB though). Anyone has one or knows of one, pls let me know...

What is it that makes it so slow? I think if it were driven by a HP-71, it would be faster. But the program sounds pretty simple... IF one wanted to do this in MCODE, how could one speed it up?




What is it that makes it so slow?

The 41. I've got the same plotter and have done the same plot. Yes it is slow. However using EMU41 or nonpareil in turbo mode with a PIL-Box or IL-ISA adapter is significantly faster.


so MCODE would make it faster. Is it the PRPLOT program that is so slow or the sin calculation?




It could be PRPLOT, the 41, or the HP-IL adapter. Hard to tell without a PRPLOT replacement.


The 41 is not very quick at any of the major factors here: calculating the SIN, probably doing some division and multiplication to scale it to the drawing size and maybe addition or subtraction for the drawing's offset, putting the text commands out, converting the number result to text, and then operating the IL which it only does at about 150 bytes per second (compared to the 71's 5,000 bytes per second). When I used the 41 for controlling equipment and printing out long lines of test results, synthetic programming sped up some of the printing operations because I could do things like embed escape sequences in quoted text. The 41 might also be inputting status from the plotter before every command, although there apparently is no danger of overrunning the plotter's input buffer!

Edited: 25 Mar 2010, 4:47 p.m.

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