From: mutazilah@gmail.com   
      
   "Salvador Mirzo"  wrote in message   
   news:874j00yfpr.fsf@example.com...   
   > cross@spitfire.i.gajendra.net (Dan Cross) writes:   
   >   
   > If I were to understand enough about RISC-V, say, to the point of being   
   > able to read and make small changes to a certain toy operating system or   
   > something like that, I would be very pleased to, say, give a lecture to   
   > a computer user's group on how things work---what a computer is, how it   
   > works, what the function of an operating system is.   
      
   That looks like a semi-concrete/coherent goal to me.   
      
   > I'm not competitive; rather, I'm cooperative.   
      
   This too.   
      
   First of all - you're going to hit time constraints. So while a   
   fantastic multiprocessing OS and GUI would be nice, it's   
   not something that Tim Paterson came up with in the first   
   version of QDOS. Even if he had less resource constraints.   
      
   And you have already answered why you don't just stick   
   Linux on RISC-V and call it a day - it's not what others   
   call a "toy" OS.   
      
   Note that MSDOS was used for a very long time in business   
   and I never heard anyone call it a toy at the time. And use   
   what instead? The Amiga? Macintosh?   
      
   You're after something simple.   
      
   And ask yourself what the simplest OS that could theoretically   
   be written is. And you're basically back to MSDOS or   
   something similar. And that's exactly what I did - write something   
   similar to MSDOS. I challenge you to find something in PDOS   
   that is "excess baggage that could be removed to simplify things   
   for new starters".   
      
   However, I did indeed simplify PDOS by way of redesign - by   
   creating PDOS-generic.   
      
   So I go back to a previous question. Do you accept the concept   
   of a BIOS - or perhaps a BIOS-like layer - or UEFI?   
      
   If so, if you provide a BIOS for RISC-V (or use UEFI), then   
   PDOS-generic (the OS) will run under that already. You just   
   need to compile it. Other than you will need to implement   
   setjmp/longjmp (assembler) too.   
      
   And one thing that isn't in PDOS-generic that I intend to add,   
   is to replace functions like syscall PosOpenFile with a syscall   
   fopen. But even that is internal to the OS. Because apps don't   
   need syscalls at all. Inspired by the Amiga, you can simply   
   call into callback functions. DLLs on Windows are similar.   
   Those things may or may not devolve into syscalls - it is hidden   
   from the user (which I consider to be a good thing).   
      
   And you don't specifically need to buy a RISC-V machine.   
   You can write an emulator. The mainframe emulator I wrote   
   is 3000 lines long - all that was needed to get gcc 3.2.3 to   
   recompile itself.   
      
   Alternatively you could focus on the BIOS (or pseudo-bios)   
   portion of RISC-V support. Or use Linux as a glorified   
   pseudo-bios. That's how PdAndro for Android phones works.   
      
   Basically, for simplicity, separate out a BIOS (or similar) from   
   the (simple) OS proper, and more options open up.   
      
   BFN. Paul.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)