2bc8f61e   
   From: et472@ncf.ca   
      
   On Mon, 8 Sep 2008, Jim Leonard wrote:   
      
   > I know this group is typically for TRS-80 people but I remember seeing   
   > Frank Durda in here (and hopefully Jeremy/Tvdog is still listening) so   
   > I'd like to ask a few questions:   
   >   
   > For fun (actually for a contest, but more for fun) I am developing a   
   > PCjr "demoscene" demo, something that will exercise the extended   
   > graphics and sound simultaneously.  To aid development, I was going to   
   > program on a Tandy 1000, because I can put a hard drive in that.  But   
   > I have some questions:   
   >   
   > - The PCjr required a hardware modification to run some Tandy 1000   
   > programs that otherwise wouldn't display.  Does anyone know why the   
   > mod was required, especially since the Tandy 1000 was supposed to be   
   > PCjr compatible?   
   >   
   I think that's your problem right there.  This is the first I've heard   
   that they were compatible.   
      
   They were aimed at the same market, and same price level, and ended   
   up with similar hardware.  But one wasn't a copy of the other.   
      
   That period was when everyone wanted to be about the same, without   
   being the same.  So there were a whole bunch of computers that   
   could run MS-DOS, but not software that accessed the hardware directly.   
      
   There were whole levels of "compatibility", the names I can no longer   
   remember.  It was only later that everyone was completely compatible   
   with others, and they all then ceased to have their own identity.   
      
       Michael   
      
   > - The PCjr has a real video IRQ on IRQ 5 -- does the Tandy support/   
   > emulate that?   
   >   
   > - The PCjr refreshes DMA via the video controller, so PIT channel 1 is   
   > used for disk drive motor timing instead.  Is this also the case on   
   > the Tandy 1000?   
   >   
   > - The PCjr has a very complete and detailed technical reference   
   > available; is there a similar tech ref for the Tandy 1000?   
   >   
   > Thanks for any help or advice!   
   >   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)