Issue No.03 - March (1969 vol.18)
A digital comparator has been attached to a PDP-4/340 display terminal. This comparator is used to detect the presence of the CRT beam within a specified portion of the display screen.
Computer displays, computer graphics, digital comparator, light pen.
N.A. Farmer, "A Digital Comparator for Use with Computer Displays", IEEE Transactions on Computers, vol.18, no. 3, pp. 269-270, March 1969, doi:10.1109/T-C.1969.222641