Anonymous asked in Computers & InternetProgramming & Design · 2 months ago

How come computer terminals back in the days only display characters in upper case letters? Was it a limitation in technology? ?

6 Answers

  • 2 months ago
    Favourite answer

    Technology and cost.  The upper-case-only devices I remember were hard-copy output devices like teletypes and printers.  These were electromechanical devices and unneeded complications mean extra cost to build, greater rates of failure, and more expensive repairs. 

    Also, there was economy in transmission code.  An uppercase-only device could operate with a 6-bit code, or even 5 bits if a "shift" strategy was used.  Double the number of letter codes from 26 to 52 and you can't fit all them into a 64-character code table (6 bits) and still have room for punctuation, space and control characters.

    For teletypes, which initially operated as a replacement for telegraph operators, there wasn't a need for lower case letters.  There aren't any in the Morse code that people were used to for writing telegrams.

    True teletypewriters, though, were electric typewriters with communications hardware added.  Those had upper and lower case letters by the late '60s, if not sooner.  All of the raster CRT terminals I saw as a student in the early '70s had full keyboards and upper/lower case, though.  The first computer terminal I used was an IBM 3741 data terminal, which was basically an IBM Selectric typewriter with a serial interface added.

    Early 8-bit computers (late '70s to mid-'80s) had uppercase-only character sets for a different reason.  These were designed to use an ordinary home television as a display device.  TV resolution was good enough to get around 200 lines with about  320 pixels per line, or 25 lines of 40 characters each using an 8x8 character cell.  That wasn't enough for clean, readable lower case. 

    But, like I said at the top, technology and cost.  TV display technology was used to keep the cost of a home computer down.  Full upper/lower case terminals were already widely used professionally, those were used on systems that cost much more than the $1,000-$2,000 one might spend on a Apple ][ or Atari 800 system.

    • ...Show all comments
    • husoski
      Lv 7
      2 months agoReport

      Funny.  Maybe funnier is, having started on APL then FORTRAN IV and then 360/370 assembler, I used to think the same thing about lower case in source code.

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  • 1 month ago

    My first home computer was a Dragon 32 which had no proper lower case characters. There again it did only have 32 K of RAM!

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  • Anonymous
    2 months ago

    Storage space used to be limited. You were paying per byte. By only using uppercase characters, that made it take up less space when compressing files. 

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  • VP
    Lv 7
    2 months ago

    Because there wasn't a need for lowercase letters until there was.

    That's pretty much how most things get invented.  Someone thinks up a need/want/desire and those that can -- create it. As long as there's technology to do so.

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  • EddieJ
    Lv 7
    2 months ago

    Everything has a cost associated with it.  Keep in mind that the characters were not just displayed but had to be stored in memory.  Lower case letters were just a luxury that no one needed.

    The original display terminals only used green on black.  There was a funny ad where a knife was plunged into a terminal and green goo oozed out.

    When they added lower case letter and 3 more colors, it seemed amazing.

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  • Snezzy
    Lv 7
    2 months ago

    Initially the computer's typewriter displayed numbers. Before that the display, if any, was just blinkenlights. (This is not quite true, but it gives the flavor.)

    The computers we have today came about in large part through IBM and its tabulating machines that used punched cards. Early-on the upper-case letters and a few signs were encoded into what became the BCDIC code. Similarly, teletype machines, using Baudot 5-level code, supported numbers, upper case letters, and a few other characters.

    You can look up the history of this stuff. It's almost fascinating. Remember, though, that way back in the Dark Ages our good friend Ada Augusta envisioned computers writing poetry and music. She was thinking of a computer that wasn't yet built at all back then. 

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