Message from discussion Questions about OpenFirmware
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Date: Sun, 11 Nov 2012 07:14:27 -1000
From: "Elizabeth D. Rather" <erat...@forth.com>
Organization: FORTH, Inc.
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Subject: Re: Questions about OpenFirmware
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On 11/11/12 3:20 AM, deech wrote:
> Hi all,
> I have a couple of questions about OpenFirmware but there hasn't been any activity on the mailing list (http://www.openfirmware.info/pipermail/openfirmware/) in quite some time so I thought I'd ask here.
> I'm having trouble seeing how the whole thing is bootstrapped.
> For instance
> 1. there's a builder.dic binary file that's used by the forth implementation and I don't see how that is built,
> 2. I can't see the code that actually parses the Forth code and converts it to assembly.
The details depend on the version of Open Firmware. Apple's system
differed significantly from Sun's, and IBM's was different still.
In most of them there is a core that was written in assembler (although
I think Sun's was meta-compiled with Forth). And none of them actually
compile machine language in the sense that a C compiler or a "compile to
code" Forth does. It's a "subroutine threaded" system, in which the
runtime code consists of sequences of calls. The reason for this is that
it's essential to be able to decompile ("see") the content of
definitions for debugging purposes, since the source is rarely available.
Elizabeth D. Rather (US & Canada) 800-55-FORTH
FORTH Inc. +1 310.999.6784
5959 West Century Blvd. Suite 700
Los Angeles, CA 90045
"Forth-based products and Services for real-time
applications since 1973."