From: gvision@ntlworld.com   
      
   "Dr John Stockton"  wrote in message   
   news:wePQrJAUCngCFwFE@merlyn.demon.co.uk...   
   > JRS:  In article , dated   
   > Wed, 11 May 2005 00:18:47, seen in news:comp.lang.pascal.borland,   
   > Jason Burgon  posted :   
      
   > >That wasn't the reason for the choice of crystal frequency at all. That   
   > >frequency in fact produces quite poor standard UART bit rates. The   
   > > reason was to do with the video display and IIRC, was chosen because   
   > >of some NTSC-specific timing parameter.   
   >   
   > Get a copy of The Timing FAQ !   
   >   
   >  358631 Feb 1 1996 ftp://garbo.uwasa.fi/pc/programming/pctim003.zip   
   >  pctim003.zip Timing on the PC under MS-DOS, K.Heidenstrom   
   >   
   > Then you won't need any IIRCs.   
      
   I already have it, and from it I extract the following paragraph:   
      
   >>   
   Historical note:  If you were wondering "Wouldn't 1 MHz have been easier?",   
   yes it would, but that would have required an extra crystal.  IBM were...   
   er, 'clever' - they used a master clock of 14.31818 MHz, and used logic   
   chips to derive the 4.77 MHz CPU clock, the timer clock, and the NTSC colour   
   subcarrier frequency for the CGA card, so they could save a few dollars.   
   <<   
      
   So before you get on you high horse and repremand a poster for not checking   
   some FAQ or other, I suggest you read (and understand) them yourself.   
      
   All you had to say in your post that my IIRC was indeed correct. Why the   
   sactimonius repremand?   
      
   --   
   Jay   
      
   Author of Graphic Vision   
   http://homepage.ntlworld.com/gvision/   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)