alt Hacker NewsStack-based architectures have an appeal, especially for mathematics. (Think of the HP calculator.) And the explanation that they didn't have enough instruction bits also makes sense. (The co-processor uses 8086 "ESCAPE" instructions, but 5 bits get used up by the ESCAPE itself.) I think that the 8087's stack could have been implemented a lot better, but even so, there's probably a reason that hardly any other systems use a stack-based architecture. And the introduction of out-of-order execution made stacks even less practical.
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> there's probably a reason that hardly any other systems use a stack-based architecture
I don't know about other backend guys, but I disliked the stack architecture because it just incompatible with enregistering variables, register allocation by live range analysis, common subexpression elimination, etc.
To expand on this a little bit more:
x86 has a general pattern of encoding operands, the ModR/M byte(s), which gives you either two register operands, or a register and a memory operand. Intel also did this trick that uses one of the register operand for extra opcode bits, at the cost of sacrificing one of the operands.
There are 8 escape opcodes, and all of them have a ModR/M byte trailing it. If you use two-address instructions, that gives you just 8 instructions you can implement... not enough to do anything useful! But if you're happy with one-address instructions, you get 64 instructions with a register operand and 64 instructions with a memory operand.
A stack itself is pretty easy to compile for, until you have to spill a register because there's too many live variables on the stack. Then the spill logic becomes a nightmare. My guess is that the designers were thinking along these lines--organizing the registers in the stack is an efficient way to use the encoding space, and a fairly natural way to write expressions--and didn't have the expertise or the communication to realize that the design came with some edge cases that were painfully sharp to deal with.