Many years ago I was watching the news when I saw someone on a Sun workstation controlling the display using an external input device consisting of a series of rotary dials. Turning them rotated and scaled the images.

I have since seen these in images connected to other systems dating into the 1960s.

Do these controllers have a unique name?

  • Before Sun, e.g. the DEC LINC came with a set of 8 of these "dial controllers". Wikipedia just calls them knobs, and I can't find any specific term for them in the manuals. – dirkt Dec 4 at 19:22
  • Ahh yes, it was LINC where I saw them again. – Maury Markowitz Dec 4 at 19:24
  • 1
    In case anyone is wondering, I was looking for this name to make a link in the Vector General article on the wiki. – Maury Markowitz Dec 4 at 19:31
up vote 3 down vote accepted

I have always heard them called "dial boxes".

I worked on a medical imaging platform about 25 years ago that was based on Sun-3 workstations, which used them to manipulate the "window" and "level" of medical images (radiologist-speak for contrast and brightness). They are called rotary encoders. Some also have a switch that can be activated by pressing down on the knob.

Old-style mechanical mice had a pair of these -- working at right angles -- to measure the movement of the mouse ball.

rotary encoder

rotary encoder with knob

  • btw. In industry they called IRC (Incremental Rotary enCoders) – Spektre Dec 5 at 8:32

They could have been paddles. Paddles were often used for games like Pong, and are a one-dimensional control which is manipulated by a circular dial. Of course, usually they have a button or something attached also.

They measure the time it takes to charge a capacitor, which varies by the resistance in the dial.

  • The term "paddles" is generally used only for controllers which have a fixed range of motion, typically measured by turning a potentiometer. Knobs that allow continuous rotation are usually sensed using rotary encoders, and that is probably a perfectly reasonable term for the controls themselves. – supercat Dec 4 at 16:19
  • @supercat You may be right about that. I'm not sure if it's what Maury Markowitz saw that time on the news. Maybe paddles were not that common on serious workstations like the Suns. – Wilson Dec 4 at 16:42
  • I've certainly seen slide pots used as general-purpose data entry devices (my DX21 synthesizer has one slide pot whose function is selected using about 40 buttons), and would expect rotary pots could be used likewise, but for most purposes I would think that rotary encoders or slide pots would be more popular than rotary pots. – supercat Dec 4 at 17:07

There are a number of traits that controllers based on a rotating component can have. The axis can be perpendicular to the mounting surface, or it can be vertical or horizontal relative to it. The range of motion can be unlimited, or the controller can be free-floating with end stops, or it can be spring loaded to the end, or toward the center. Those traits alone would describe twelve different kinds of controllers, all of which I've seen in various places. I think the term "paddle controller" or "potentiometer knob" would would be understood as referring to a controller with an axis perpedicular to the surface and a limited range of free-floating motion, and "rotary encoder" would be understood as referring to a control with the same orientation that allowed continuous rotation. The term "vertical scroll wheel" would likely be understood as being similar to the control found on many mice (with or without a clicker), and "horizontal scroll wheel" would be understood as a similar control oriented differently.

Sun called these "SunDials", these units had 8 dials. They also had an input device with 32 buttons, called "SunButtons".

Here is a description of the SunDials device taken from section 9.4 of the SunOS 4.1 Release Manual:

SunDials is an image-manipulation input device for Sun-3 and Sun-4 workstations, using an RS-232 serial interface. The desk-top dialbox is compact, measuring 8.63"xS"x1.1S".

The dials can be programmed to change colors and manipulate images. SunDials is designed to perfonn CAD image manipulation such as scaling, translating, rotating, and zooming.

Sun View directs SunDials input to the process owning the window (where the cursor is located). SunDials extends the interactivity of the display controller beyond the current capabilities of a mouse or digitizing tablet.

The SunDials device driver is integrated into the GENERIC kernel. No optional software or kernel reconfiguration is required, but kernel reconfiguration is recommended for optimal performance.

See the dialtest(6) manual page for details

Sun's documentation uses the terms "dialbox" and "dials" to refer to these generically.

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