From: cross@spitfire.i.gajendra.net   
      
   In article <87ikoh13fx.fsf@example.com>,   
   Salvador Mirzo   wrote:   
   >cross@spitfire.i.gajendra.net (Dan Cross) writes:   
   >> [snip]   
   >>   
   >> So it's hard to see how DOS really qualifies as an OS, despite   
   >> the OS-like abstractions it provides.   
   >   
   >Thanks for the explanation.   
      
   Certainly; happy to do it.   
      
   >I now think that DOS is useful today in   
   >illustrating the definition (in a negative way) as you just did.  I   
   >actually plan to understand more about DOS just to be able to personally   
   >give an answer like that.   
      
   This, I think, is reasonable.   
      
   >It also seems very useful precisely to expose a programmer to the entire   
   >machine.   
      
   But this I'd push back on, at least until I understood the goal   
   a bit better.  Is the intent to understand how systems work at a   
   low level?  To understand systems architectural more generally?   
   Or as a, "how did we get here?" exercise in systems evolution?   
      
   While understanding some bits of DOS, the BIOS, and the context   
   around the late 70s/early 80s PC/home computer indistru is   
   essential for the last, for first two, there are other, better   
   ways to understand the machine than studying DOS and the BIOS.   
   And in particular, modern systems, even those built around x86   
   CPUs, bear little resemblence to the original IBM PC.   
      
   Personally, I think one is better off coming at things from a   
   fresher, more modern perspective, unencumbered by the follies of   
   the past, as opposed to looking at things through the lens of   
   1979 Boca Raton.  To understand hardware at the most basic   
   level, one would be better off looking at something like the   
   Arduino platform, which is almost stupidly simple, but by   
   design, very approachable.  To understand architecture at a more   
   rational level, look at something like RISC-V; x86, and x86_64,   
   carries too much baggage from the past that obfuscates   
   understanding.  To understand OS design, or even firmware, there   
   are better examples out there.  I'd look at something like MIT's   
   materials for their OS course, in particular xv6.   
      
   The negative case study aside, or spelunking into the history of   
   the PC platform, I can't think of a good reason to study DOS.   
   Historically important, yes; but otherwise an exemplar of how   
   over-compensating for technical constraints can lead to bad   
   technology.   
      
   	- Dan C.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)