Re: the stack


<bob@xxxxxxxxxxxxxx> wrote in message
news:f45b4608-fafa-4fd3-b73d-d34d84e4287d@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I was just wondering why the stack grows downwards on x86 processors.


The short answer: it was designed that way.

The 8086 was compatible with the 8080. Stanley Mazor of the 8080 design
team designed the 8080 stack that way:

"Deleting the on-chip stack saved chip area, but was a net advantage to the
user -now the stack had unlimited size. I defined the stack as growing
downward from the high end of memory; this facilitated indexing into the
stack and simplified displaying the stack. This was abandoned on the 8086."
http://www.xnumber.com/xnumber/Microcomputer_invention.htm

By "abandoned ...," I think he means the stack was put back on-chip for the
8086.

Numerous past threads on comp.arch, comp.arch.embedded,
alt.folklore.computers, or comp.dsp will blame the 8080, PDP-11, or K&R C...
depending on the author...


Rod Pemberton

.

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