They work in a similar way to scan cameras explained at http://www.ussrphoto.com/Wiki/default.asp?WikiCatID=51&ParentID=49&ContentID=1230&Item=Scan+camera+principle

This camera designed for copy small size documents (approximately 6x4cm). The shatter and film advance all mechanical. Camera does not have any electronics. Film size, I believe, 16mm not perforated. Camera used 2x1.5 Volts batteries of odd size to power 4 small light bulbs inside. Batteries of this size were common in USSR in 70-x. But I can not find them anywhere now. It is unknown to me where such cameras were used. Perhaps at customs, to make copies of passports for people entering and living USSR. Or may be at archives. It is unlikely it was used by military or secret services because of the limitations of the camera design like comparatively big size (approximately. 10x15cm), small film capacity and it bulky to use and reload. Also the way camera built (pretty cheaply) it would not qualify for military/KGB use. But I can be wrong. More info needed on this camera.

The S-112 uses the same film as the Kopir. It is 21 mm wide and cut from 35 mm. The negative size is roughly 18 x 24 mm. - David Tomlinson.

see also http://www.ussrphoto.com/Wiki/default.asp?ContentID=1210&ParentID=1&WikiCatID=17