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From: ericb@athertn.Atherton.COM (Eric Black)
Newsgroups: comp.sys.amiga.tech,comp.sys.amiga
Subject: Re: Generating ROMable downloads for embedded 680x0 type machines
Message-ID: <178@mango.athertn.Atherton.COM>
Date: 2 Apr 88 01:48:13 GMT
References: <17369@glacier.STANFORD.EDU>
Reply-To: ericb@mango.UUCP (Eric Black)
Organization: Atherton Technology, Sunnyvale, CA
Lines: 58
Keywords: ROM, embedded, 68000, 68010

In article <> jbn@glacier.STANFORD.EDU (John B. Nagle) writes:
>
>     I need to generate ROMable code for an embedded 68010-like machine.
>Are there any programs available for the Amiga that will help with this?

There is a set of programs on Fish disk #26 (I believe; I'm not sure
which one), which take Amiga load files and "de-hunk" them to
create ROM-able download files.  There is a utility to create the S-records
that many PROM-bombers understand.

This allows you to write code using whatever assembler or compiler
you want, as long as you follow the rules for creating ROM-able code.

These rules are much easier to follow if you are writing in assembler,
but you can do it in C if you try hard (I've done it successfully with
both Lattice and Manx).

If you're asking the question, then I will assume that you know how
to write ROM-able code...

Anyway, if you are using an Amiga compiler or assembler, be careful not
to use any routines (or C functions, even ones the compiler may reference
for you) that are Amiga-specific.  Obvious ones are the Amiga libraries
loaded on demand at runtime.  Allowable ones are runtime library routines
such as string handling which are linked in.  Make sure you tell the
compiler or assembler to generate position-independent code (this is
easy to to [usually] on the Amiga tools).

Here's where your coding technique is important.  You must EXPLICITLY
set variables to initial values in your code.  The initial values will
be in ROM.  Your variables will end up in BSS.  You must make sure that
you keep them straight.  Make sure that your BSS is origined wherever
your RAM turns out to be, and explicitly copy values from the defined
constants in ROM into the variables.  It's easy in assembler, not quite
so easy but still quite doable in C.

Once you have generated your load module, use the "unhunk" program on the
Fish disk to create a file which is quite similar to a Unix a.out-format
file, containing three separate segments -- text, data, and bss.
You can set the origin for each of the three segments separately to
whatever physical address you need, based on your machine with the
embedded 68010.  Put the initialized data segment right after the
text segment (this is the default).  These will be burned into ROM.

Pass the file thus created through the separate program to create
S-records, and download them to your PROM-bomber.

If you can't get hold of the correct Fish disk (I think it's #26, but
I'm not sure), I can mail you the code, since I am the author.

I have used it successfully for generating ROM-resident code for
68000-based hardware using my Amiga.

Hope this helps!

-- 
Eric Black	"Garbage in, Gospel out"
Atherton Technology, 1333 Bordeaux Dr., Sunnyvale, CA, 94089
   UUCP:	{sun!sunncal,decwrl,hpda}!athertn!ericb
   Domainist:	ericb@Atherton.COM