The Diablo printer was the first low-cost device capable of producing typewriter-quality output. It had a daisy-wheel print mechanism capable of proportional spacing, superscripts and subscripts, and overstriking. It had a set of symbols for line drawing plus the ability to position the character anywhere on the page so it was able to draw diagrams as well. You had to be a bit careful as, without pin-registered rollers, the paper tended to move a bit so there was an art in getting graphics produced of reasonable quality.
Horizontal placement could be controlled in increments of of 1/120in and vertical placement is controllable in increments of 1/48in. Thus creating diagrams was not that easy. Bob Hopgood wrote a GINO-F backend so that graphical output to the Tektronix displays could also be printed on the Diablo.
With a system like RUNOFF on the Prime it was possible to generate all the documentation you needed of a quality that was acceptable to a publisher or printer.
Both the Texas and Tally printer companies are still in operation and it is possible to purchase consumables and spare parts for the Texas 820 in 2005.