The 1350A was effectively a video interface used by digital computers to drive analog CRT monitors. The standard unit came with an HP-IB interface (52101A); 16-bit parallel (52103A) and RS-232-C interfaces (52102A) were also available. The 1350A was often used with the 9825 to give that computer large-screen output. The 9825 sent digital vector commands to the 1350A, which translated these commands to drive an analog monitor. The resultant display is very high resolution. This is because the electron beam on the monitor travels directly from one point on the phosphor screen to the next (whereas the electron beams on digital display scan the entire screen at a set frequency and resolution, illuminating only those dots specified by the program). The 1350A could also produce all 96 upper and lower case letters and most of the special characters in the full ASCII set.