(4010 a I only AFAIK, the Tektronix external "hard copy units" for their DVST display terminals (4002A, 4010, 4012, 4014, and others that were integrated into various systems (e.g., the 4081 computer system, and 4051/4052/4054 desktop computers)) were dry-process devices. The paper was a dry-silver paper that was photosensitive, but it was developed by heat rather than by chemicals. It is possible, in the very early days of the DVST terminals, that some kind of wet-process hard copy may have been used...or that perhaps a third party developed a wet-process hard copy unit, but my only experience was with the thermal-developing dry-silver paper hard copy units. I used these devices extensively in my time at Tektronix, and became quite expert at troubleshooting/adjustment of the hard copy units. There were no chemicals or toners involved. The paper would come out of the machine quite warm from the developing process. The tube in these hard copy devices was indeed weird...wide, but not very tall. It produced a single scan line that was synchronized with the motion of the paper through the machine. The scan line was driven by the terminal, which used a low-intensity scanning beam to "read" the charge on the storage element of the display screen, and sent the analog signal from the read-out image to the hard copy unit. The DVST technology that Tektronix created for these terminals was very much an example of the extreme levels of CRT technology and knowledge that existed within Tektronix during those days. Just about every tube they used for oscilloscopes, scan converters, and all of the DVST tubes were designed and manufactured in-house at TektroniX HQ in Beaverton, Oregon. The CRT building was one of the earlier buildings on the Tektronix campus there. It was quite a place to visit. Even in the late 1970's, there was amazing CRT development going on there for building things like the tube for the first 1GHz (analog) oscilloscope. Rick Bensene The Old Calculator Museum http://oldcalculatormuseum.com