From Wiki

Hewlett Packard 82240A Infrared Thermal Printer

• Type: Calculator Accessory
• Size: 3.5 x 7.25 x 2.5 inches / 9 x 18.5 x 6 cm
• Serial number: 2937S10290
• Date of Manufacture: September 1989

With manual. Small and wedge-shaped, the perfect accessory for the 28s, and not bad for the 48 series, too. (The 48 required a change in the character set in the printer, so HP brought out the 82240B. But for us early-adopters, they provided an easy work around so 48s could also use the 'A' model.

Runs on 4 AA batteries. An AC adapter can be plugged into the back to make the batteries last longer, but the batteries are required for the occasional high current draw. (The AC adaptor can be just about anything, 9-12 volts AC or DC output, 500 mA, as long as the plug fits.)

Takes 82175A paper. (Or something the same size, at least. HP no longer sells this paper. Of course.)