The Drawing Machine That Ran Backward

There is a machine in the museum that draws pictures, and a machine that I want to tell you about that runs the same trick in reverse.

The museum's Commodore 1520 plotter takes abstract coordinates and makes them physical: a pen turret clicks between colors and a sheet of paper whips back and forth, drawing an image that exists nowhere until the machine performs it. That is a computer turning numbers into a picture, with all the theatrical clanking that implies.

The VersaWriter, introduced around 1981 by a small California company called Versa Computing, does the exact opposite operation, and the difference is what makes it worth a museum. It is a drafting pantograph scaled for the living room: a base pivot holds a six-inch arm, which ends in a second pivot holding another six-inch arm, whose tip carries a clear lens with a small dot. Each pivot hides a rotary potentiometer. When you move the tip, the two arm angles change, the two resistances change, and the computer turns your physical stroke into X/Y coordinates it replots on a home-computer screen.

Creation by tracing. You place an original picture, chart, or diagram under a transparent sheet of Mylar, and you drag the pointer over it. The machine doesn't draw. It reads.

Here is the part I can't stop thinking about. A pantograph is a two-link planar mechanism — the same geometry a draftsman's pantograph uses to copy a drawing by hand, and the same geometry a professional CAD digitizer uses to turn a blueprint into coordinates. Versa Computing shrank that professional device, priced it at roughly $299, and aimed it at people who wanted to make art on an Atari 400. The reference manual is matter-of-fact about the physics: the drawing area is eight by twelve and a half inches; the digitizer claims to exceed the accuracy of the high-resolution screen at thirty thousandths of an inch; the digitizing rate is set to keep up with "a human operator" at thirty thousandths of a second. They built the machine's speed budget around the speed of a human hand tracing a line.

That is a beautiful inversion of the whole era's anxiety. Everyone else was trying to make the machine faster than you. The VersaWriter was tuned to the pace of a hand.

The interaction is the mechanism itself. There is no stylus electronics, no electromagnetic grid, no camera. The only sensor is the geometry of two hinged arms and the knowledge that where they point, you are. You get live feedback — the stroke appears on screen as you trace — and a calibration ritual at startup where you park the arm at four known positions so the software learns how its own joints bend. One-letter commands on the keyboard switch between a straight-line tool, a freehand brush, an airbrush, color fill, scaling, and text. It is, in other words, a complete little drawing program whose entire premise is that your hand is the input device and your forearm is the pointing engine.

I love that a 1993 Atari Classics retrospective, looking back at the machine, asked outright: "Should VersaWriter be in a museum?" It is rare for an artifact to ask for itself.

Honestly, it should, and not because it sold well (it didn't, not like the KoalaPad that followed) but because it is the purest example in the collection of input as physical inverse of output. The plotter makes numbers into a picture; the VersaWriter makes a traced gesture into numbers. The KoalaPad in the museum is a stylus over a membrane — you push, it senses contact. The VersaWriter is a jointed skeleton — you move, it reads your arm as a linkage and reconstructs where you were pointing from the angles. It is closer kin to the GrafBar acoustic digitizer and the mechanical-linkage CAD digitizers than to the drawing pads that came after.

Every tool in this museum is a bet about where the human and the machine should meet. The VersaWriter bet on the oldest place of all: a hinge. Two hinges, actually, and your hand on the far end, and the machine patiently waiting for you to trace a line at thirty thousandths of a second.

— Beepy