x86 has a very, very limited set of general purpose registers
it promotes a very inefficient style of development on the lowest level (CISC hell) instead of an efficient load / store methodology
Intel made the horrifying decision to introduce the plainly stupid segment / offset - memory adressing model to stay compatible with (at this time already!) outdated technology
At a time when everyone was going 32 bit, the x86 held back the mainstream PC world by being a meager 16 bit (most of them - the 8088 - even only with 8 bit external data paths, which is even scarier!) CPU
For me (and I'm a DOS veteran that has seen each and every generation of PCs from a developers perspective!) point 3. was the worst.
Imagine the following situation we had in the early 90s (mainstream!):
a) An operating system that had insane limitations for legacy reasons (640kB of easily accessible RAM) - DOS
b) An operating system extension (Windows) that could do more in terms of RAM, but was limited when it came to stuff like games, etc... and was not the most stable thing on Earth (luckily this changed later, but I'm talking about the early 90s here)
c) Most software was still DOS and we had to create boot disks often for special software, because there was this EMM386.exe that some programs liked, others hated (especially gamers - and I was an AVID gamer at this time - know what I'm talking about here)
d) We were limited to MCGA 320x200x8 bits (ok, there was a bit more with special tricks, 360x480x8 was possible, but only without runtime library support), everything else was messy and horrible ("VESA" - lol)
e) But in terms of hardware we had 32 bit machines with quite a few megabytes of RAM and VGA cards with support of up to 1024x768
Reason for this bad situation?
A simple design decision by Intel. Machine instruction level (NOT binary level!) compatibility to something that was already dying, I think it was the 8085. The other, seemingly unrelated problems (graphic modes, etc...) were related for technical reasons and because of the very narrow minded architecture the x86 platform brought with itself.
Today, the situation is different, but ask any assembler developer or people who build compiler backends for the x86. The insanely low number of general purpose registers is nothing but a horrible performance killer.
