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28864Re: [midatlanticretro] Re: Altair 8800 Web Emulator

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  • B. Degnan
    Jan 8, 2013
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      > >
      > On the Altair do you actually use the _ key for deleting a character? On
      a
      > teletype they normally used the rubout key that gave code 127. On modern

      > keyvoards that is normally the delete key and backspace used code 8.
      > The teletype doesn't have a backspace key though you can generate the
      > code with control-h.
      > (Rubout third row third from right)
      > http://www.pdp8online.com/asr33/pics/kbd_top.shtml?large
      >
      > THe printing _ is because of teletypes. A teletype can't back up other
      than
      > a carrage return. Even if it did you wouldn't be able to reliably read
      > the new character printed on top of the old so they printed the
      underscore
      > for each character "backed up". On the PDP-8 you use the delete key and
      > it prints the _ when configured for teletype.
      >

      In PDP 8 OS/8 using a glass vt102 terminal with a backspace key, under
      standard configuration, use of backspace will generate an error even if
      your command looks correct before you hit enter

      If you type this..
      .RUN RKA0;

      ..and then use the backspace key to correct (change semi-colon to
      colon)...
      .RUN RKA0:BASIC.SV [enter]

      ...OS/8 will return an OS syntax error.

      My original point - you can find a way to add backspace ability, but it
      was not really an option back then so you have to decide whether it matters
      to you or not to bypass the historic limitation of the time.

      I believe that there is value to experience what it was really like to work
      in this environment without modern shortcuts. If to engineer a new program
      you are required to toggle bootstraps, load a tape, enter code by hand,
      punch the tape on the teletype, and so on you'll start to change your
      approach to programming. The first thing you realize is that it's best to
      try to write and debug as much of the code by hand before you enter into
      the computer. That's why a lot of Altair docs I have come upon have sheets
      and sheets of pseudo code and hand-written listings along with the manuals.
      People did not use the computer to write and edit code like they do today,
      too time consuming. You had to be more precise in your data entry and more
      organized in your approach. No one would want to sit there for a half hour
      to punch a tape, then another half hour to run the tape just to find a
      single syntax error crashes the whole program. That's why there were a lot
      less people doing programming and hardware back then, this kind of work was
      not for everyone. It gives you a real appreciation for those people
      (before my time btw) who did all of this stuff when it was new back then,
      and what motivated the likes of Woz/Jobs to make something easier to use.

      Not everyone has the luxury of walking up to a computer with a teletype. I
      think it would be a great service if we had an exhibit / demo for MARCH's
      museum to show people what it was like to use a teletype for I/O and
      program storage. I would not recommend allowing the public to use it
      though, it'd have to be a ready-to-go demo for someone that had an hour to
      witness the entire process, maybe with a little lecture to kill time
      between the tape loads/punches.

      Bill
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