[gdwatson]

It was a clever hack for porting existing code. But it doesn’t scale at all – you’ve just described adding four registers to a register-starved architecture in order to solve the issue for one CPU generation or so.

[peterfirefly]

Segment prefixes were rarely needed and you didn't need to spend any of the precious mod/rm bits on segment registers. The GPR count was limited to 8 partly because of the 3 bits allocated to specifying them and partly because of limited die space. Segment registers only added slightly to the latter cost.

[juancn]

Yeah, but it was probably the right call at the time.

Backward compatibility was a breath of fresh air at a time were code needed constant porting and rewriting. No two machines were alike.

It's one of the reasons the PC became so popular.

[rob74]

Plus all this pointer juggling would have been more or less ok (or not ok, but doable) when programming in assembly, but for a compiler it would have been a recipe for disaster...

[bluGill]

I'm sure a modern compiler would have no problem with it, but in 1980 optimizer technology wasn't there yet. Modern compilers use more memory that engineers would dare dream of in 1980.

By having no problem I mean we know enough about writing an optimizer to write such a thing. I don't think any compiler does, just that they could.

[trollbridge]

Compilers in 1980 generated 64k code segments and had no other memory model.

Most people wrote assembler particularly if they wanted to use more then 64k.

Most non assembly programs were interpreted oddly enough and most such interpreters were also mostly 64k.