From: james.harris.1@gmail.com   
      
   On 13/07/2021 05:34, muta...@gmail.com wrote:   
   > On Tuesday, July 13, 2021 at 1:39:35 PM UTC+10, wolfgang kern wrote:   
   >   
   >>>> but it become a five byte   
   >>>> opcode in PM32:   
   >>>> bb 44 33 22 11 MOV ebx.imm32   
   >>>> or a four byte:   
   >>>> 66 bb 44 33 MOV bx.imm16   
   >>   
   >>> This 4 byte one looks like it will work on both PM32   
   >>> and RM16.   
   >>>   
   >>> That's exactly what I'm after.   
   >>   
   >>> It will all work, right?   
   >   
   >> No, the 66 override reverses the default operand size.   
   >> so it makes 16 bit within PM32 and 32 bit within PM16/RM.   
   >   
   > No. On a real 8086. The x'66' will be ignored. So a real   
   > 8086 and PM32 will both work, right?   
      
   Hi Paul,   
      
   Forgive me for being critical but if I understand what you mean by the   
   above (which is by no means certain) I think you are going about this in   
   the wrong way and could cause yourself all kinds of problems down the line.   
      
   I thought you were writing your code in C (C90 specifically). Well, C is   
   designed to be portable so it should let you write code which will run   
   on 8086, 80286 and 80386 machines - but the C approach to such   
   portability is compilation for the different targets. C provides   
   source-code portability, not object-code portability. It is normal with   
   C to recompile a piece of source for different targets. An 8086 is a   
   different target from 80386, just as it is from 68000.   
      
   If you want /binary/ compatibility you might be better writing in Java   
   or Pascal.   
      
      
   --   
   James Harris   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)