I was wondering who invented the blinking of a cursor, because I was just thinking if it wouldn't blink the UI would be a lot less responsive.. so this must have been one of the first signs of response UI design. Was this IBM? I'm to young to make guesses though.

Or if this question would be impossible to answer, what is the first sign of a blinking cursor in computer history.


2 Answers 2


Here's the patent for the blinking cursor patent: http://www.google.com/patents/US3531796

According to that, it was invented by Charles A. Kiesling at Sperry Rand. Patent filed Aug 24, 1967, granted Sep 29, 1970. This isn't iron clad proof that it was first invented at that time, but the time seems about right (computers were getting powerful enough that engineers were starting to care a little bit about user convenience) and Sperry Rand was one of the big players in computing at the time.

  • That's interesting, because I remember reading Tim Mott and Larry Tesler talking about making the cursor in Gypsy blink so it wouldn't be mistaken for a capital "I". That doesn't mean they invented it, though :)
    – daydalis
    Commented Jan 28, 2013 at 11:54
  • This brochure, from Sperry, mentions blinking text. archive.computerhistory.org/resources/text/Remington_Rand/…. It was published before 1967. Concurrent with Sperry's work, ARPA work led to the mouse (en.wikipedia.org/wiki/Douglas_Engelbart) which (I assume) implies a cursor - perhaps a blinking one. Commented Jan 28, 2013 at 13:50
  • I actually did mean the text cursor the blinking '_' or '|' so my question is answered, therefor I disagree with @kontur which added the mouse tag where the mouse was invented much later at an era where X window system was being invented where much more of UX was laid already. While I was looking for this father of UX with the blinking cursor. This patent proves that it was for UX purposes as the blinking cursor would should 30 frames cursor and 30 frames the selected letter, unintentionally it also made it more aware that the computer is responsive by blinking at the end of line (30f no char)
    – Dylan
    Commented Jan 28, 2013 at 16:49
  • It's interesting to note that some text display systems have hardware cursors, and some simply display a particular character or apply some formatting at the cursor position. Interestingly, both cursor-display approaches are used on both systems whose hardware can only write text at the current cursor position and those which can write text anywhere without regard for the cursor. Another interesting note is that on some systems outputting a character to the display resets the blink cycle, while on other systems it free-runs.
    – supercat
    Commented Oct 30, 2013 at 15:52
  • 2
    Interesting to learn that frivolous UI patents went all the way back to 1970.
    – DA01
    Commented Jul 22, 2014 at 5:07

Simple answer, it was Charles A. Kiesling Sr. He was my father and he did indeed write the code for the blinking cursor when he worked at Sperry. He passed away yesterday in Minneapolis at the age of 83. I remember him telling me the reason behind the blinking courser and it was simple. It was not because it looked like an "I". He said there was nothing on the screen to let you know where the courser was in the first place. So, he wrote up the code for it so he would know where he was ready to type on the Cathode Ray Tube. It ties in with this patent for the display stuff he put together for the screens back in the day. http://www.google.com/patents/US3497760

And a foot note to this, he was not happy when the first Apple computers came out and they had is _ blinking on the screen. Since he worked for the company, he let Sperry deal with it as he wrote the code for Sperry.

  • 4
    I'm sorry for your loss, and sorry to hear that yet another pioneer of computers as we know them has passed away. Thanks for your contribution!
    – André
    Commented Jan 3, 2014 at 8:20
  • 1
    May your late father RIP, what a contribution he made to the world we live in.
    – Brodie
    Commented Jan 3, 2014 at 14:35
  • 2
    Great respect your father may he rest in peace. I feel honored that this question that popped up in my mind actually got answered by the son of my question's answer.
    – Dylan
    Commented Jan 16, 2014 at 13:55
  • I don't remember any Apple computers which would behave as described by the patent prior to the Apple //e. My recollection is that on the Apple I the cursor would always blink between "@" and nothing [it couldn't have a character underneath it] and on the Apple ][, the cursor was displayed by switching between normal and reverse video. Was the complaint with the Apple //e, or some model that I'm unfamiliar with that may have been changed before broad public release, or could there be a non-blank character under the cursor of the Apple I?
    – supercat
    Commented Jan 16, 2014 at 22:49
  • 2
    – Sam
    Commented Jun 15, 2014 at 9:03

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