Shirt pocket plotter for HP41


At HP in Colorado Springs, 1981 or 1982, we had some visitors from Palo Alto who showed us a shirt pocket plotter. It looked like a case for eyeglasses which broke open in the middle. The two halves were connected by a telescoping flat bar at the bottom and another bar (for the pen) at the top and clicked into place with enough space between then to engage a piece of 8.5" wide paper. The engineers mentioned a new grit roller system which I had not heard of at the time. This mini plotter connected via HP-IL to an HP41. The plotter drew a space shuttle - a wire frame image many of you have seen.

We were told not to take pictures or even talk about the project until it got to market. I never saw or heard about the mini plotter again but did see the first of the grit-roller plotters come out in a much larger size - the 7470A.

Watching the little plotter was fascinating. When the paper was loaded, it moved in-and-out several times, rather slowly. Then a pencil stylus came out of one half of the pack and went back and forth while the paper moved up and down to create the line image.

I have mentioned this encounter to several people and nobody seems to remember it. Am I in the Twilight Zone? Can anyone confirm what I know I saw?


I left HP in 1980. At least two or three years earlier, in Lovelend, Colorado, I attended a meeting where HP labs people demonstrated grit-wheel plotting. There were two projects at the time. I am pretty sure they were called SweetPea and SweetLips. SweetPea eventually became the HP 7470 plotter. I imagine the mini plotter you're describing was Sweet Lips. The paper went back and forth through the grit wheel/capstan pinch roller initially to impress tiny indentations in the paper, creating a unique sort of rack and pinion between the paper (rack) and the grit wheel (pinion). This was the essential innovation developed at HP labs and was the basis of the 7400 series HP plotters, which grew and grew. I don't think the mini plotter ever made it to market because ink-jet printers quickly took over.


Thanks, Steve

The thing that intrigues me about this is having a plotter in you shirt pocket. Pure HP41 territory. I can just envision that prototype sitting in some box in a warehouse....

When'd you work at HP Loveland? I worked there pt while I went to CSU 1974-76. Continued in Colorado Springs after graduating until 82.



I worked at HP in Northern Colorado (Loveland and Ft. Collins) from 1975-1980.

I admit, a shirt-pocket plotter would have been cool. These days, I'm trying not to carry so many things in my pocket. I think that a connection to wireless printers and plotters is much better.


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