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From: Nobody <nobody@nowhere.com>
Subject: Re: Python CPU
Date: Sun, 03 Apr 2011 22:37:16 +0100
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On Sun, 03 Apr 2011 10:15:34 -0700, John Nagle wrote:

>      Note that if you run out of return point stack, or parameter
> stack, you're stuck.  So there's a hardware limit on call depth.
> National Semiconductor once built a CPU with a separate return
> point stack with a depth of 20.  Big mistake.

The 8-bit PIC microcontrollers have a separate return stack. The PIC10 has
a 2-level stack, the PIC16 has 8 levels, and the PIC18 has 31 levels.

But these chips range from 16 bytes of RAM and 256 words of flash for a
PIC10, through 64-256 bytes of RAM and 1-4K words of flash for a PIC16, up
to 2KiB of RAM and 16K words of flash for a PIC18, so you usually run out
of something else long before the maximum stack depth becomes an issue.