Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucsd!sdcsvax!ucsdhub!hp-sdd!hplabs!hp-pcd!hpcvlx!everett
From: everett@hpcvlx.HP.COM (Everett Kaser)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Why CTRL-2 and CTRL-6 and not others???
Message-ID: <101000048@hpcvlx.HP.COM>
Date: 21 Apr 89 15:21:25 GMT
References: <1673@blake.acs.washington.edu>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 47


 djo7613@blake.acs.washington.edu (Dick O'Connor) writes...

>While playing with macro-building in PC Tools Deluxe's Macro Editor,
>I tried all of the <CTRL>-number combinations using the top row number
>keys and could only assign CTRL-2 and CTRL-6 as hot-keys.  It didn't
>seem to recognize the other eight potential CTRL-digit combinations.
>I don't know much about XT keyboard scan codes (it's a Zenith Z159, if
>it matters).  Is this a result of something PC Tools is doing, or is it
>related to those particular scan codes regardless of application?
>Dick O'Connor

No, it's normal to all PC's.  If you look at an ASCII character table,
you should notice (with a little prodding :-) that the ASCII character codes
that are generated when you hold down the CTRL key are simply the ASCII
code of the key WITHOUT the CTRL key, minus 64.  Yea, I know that was a
poorly written sentence and difficult to understand.  So, a small example:

    -------CTRL--------          -------NORMAL--------
     char  ASCII-code             char   ASCII-code
      ^@     0                     @       64
      ^A     1                     A       65
      ^B     2                     B       66
      ^C     3                     C       67
          .                            .
          .                            .
          .                            .
      ^Z     26                    Z       90
      ^[     27                    [       91
      ^\     28                    \       92
      ^]     29                    ]       93
      ^^     30                    ^       94
      ^_     31                    _       95

Now, the PC BIOS pretty much ignores the shift key when the CTRL key is
down.  The BIOS only uses one 'shift' key (SHIFT, CTRL, ALT) at a time, and
CTRL seems to take precedence over SHIFT.  So, CTRL-A is the same as CTRL-a
(CTRL-SHIFT-A) and CTRL-2 is the same as CTRL-@ (CTRL-SHIFT-2).  Ditto for
CTRL-6 versus CTRL-SHIFT-6 = CTRL-^.  None of the other number keys have
a symbol as the shifted character that lies in the range from 64 to 95.

Understand now?  Perfectly simple?  Nothing is simple when it comes to
keyboards.  Trust me.  I know.  :-)

Everett Kaser
!hplabs!hp-pcd!everett
everett%hpcvlx@hplabs.hp.com