Which turns out to be the case:
That’s a stack of three “Homage” Tek CC bottom decks under a Genuine Tektronix Circuit Computer.
The black scale at the top of the picture (and the bottom of the stack) came from a 1 mm cheap pen in the collet holder, the two green scales come from a 0.5 mm Pilot V5RT cartridge in its new holder, and the Original is (most likely) laser-printed back when that was a New Thing.
As always, paper makes a big difference in the results. The brownish paper is 110 pound card stock with a relatively coarse surface finish. The white paper is ordinary 22 pound general-purpose laser / inkjet printer paper.
The 1.0 mm pen (top) doesn’t much care what it’s writing on, producing results on the low side of OK: some light sections, no blobs. Perfectly serviceable, but not pretty.
The Pilot V5RT really likes better paper, as it bleeds out on the card stock whenever the CNC 3018XL so much as pauses at the end of a stroke. Using white paper slows, but doesn’t completely stop, the bleeding, making the blobs survivable.
I’ve been using card stock to get stiffer, more durable, and more easily manipulated decks, but the improved line quality on the white paper says I should laminate the decks in plastic, just like the original Tektronix design.
No surprise there!