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From: bryce@hoser.berkeley.edu (Bryce Nesbitt)
Newsgroups: comp.sys.amiga
Subject: Re: MINIX port to A1000
Message-ID: <21608@ucbvax.BERKELEY.EDU>
Date: Thu, 5-Nov-87 02:35:09 EST
Article-I.D.: ucbvax.21608
Posted: Thu Nov  5 02:35:09 1987
Date-Received: Sat, 7-Nov-87 19:06:18 EST
References: <8711050534.AA25885@jade.berkeley.edu>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: bryce@hoser.berkeley.edu.UUCP (Bryce Nesbitt)
Organization: University of California at Berkeley
Lines: 79

In article <8711050534.AA25885@jade.berkeley.edu> JPARR@UREGINA1.BITNET (John Parr) writes:
>
>     As part of the requirements for a graduate level computer science class,
>I am seriously considering porting MINIX to the A1000... 
>     Also, I am considering building the MINIX kernel into the WCS of the
>1000.  If I have any thoughts of being so ambitious, I need to know just
>what makes a kickstart disk tick.  Anybody out there in net land know the
>kickstart format?

First sector on the disk contains "KICK" ($4b49434b), the rest is zero.
The next 256K worth of sectors contain the Kickstart data, 512 bytes
to a sector.

The "ROM" image must have a correct 32 bit additive checkum (with
extend) or the system will re-kick on reset.

The first word of the "ROM" must be $1111. Next word $4EF9 (A
JMP instruction in 68000).  Next long is the address to jump to.

Your "ROM" goes from $FC0000 to $FFFFFF.


>     Another possibility is running MINIX as a task under AmigaDOS.  This
>would be really neat, but I forsee mega problems with MINIX bumping into
>AmigaDOS.  (i.e. which memory manager really controls the memory, etc.)

You could also hijack the Amiga after Kickstart.  Exec (the executive)
even has a nice way to do this.  As long as MINIX obeys exec's
allocated memory there should be enough low level hardware
arbitration built in to the Amiga to deal with the rest.

Any comments from the world on two operating systems running as
equal partners on one machine?  (Shades of Janus or better yet
Symetrix)

The only problem here is that descriptions of resources (the hardware
arbitration mechanism) are almost totally absent from any of the
technical manuals.


>     Specifically, could anyone out there provide me with a memory map of
>the Amiga internals?  A detailed map would be peachy keen, but I'd settle
>for anything....
>  ...Oh yeah, before someone says, "buy the Amiga Technical Reference
>manual" or "wonder book X" allow me to say that I'd love to.  Thing is
>there ain't nobody around who'll sell 'em to me and I don't just have
>oodles of time to waste in a mail order situation.

If you are going the scratch route you want the "Amiga Hardware Reference
Manual".  Available from Addison Wesley Publishing, Reading MA 01867
617-944-3700.  $24.95.

Or, better yet, I'll post a complete memory map of all absolute
ram address used by the Amiga right here:

------- start -------

_AbsExecBase	EQU 4

-------- end --------

Exhausting, eh?  You just can't work with the Amiga without some
references, sorry!  

(The Rom Kernel also uses $100-$3ff, but other than the first two
longs I'm not quite sure what for, and user programs never see it)
The supervisor stack is $1800 bytes from the top of local memory down.
(local chip top or local $C0000 top.  Again, this is transparanet to any
user program.)


>userid: JPARR@UREGINA1.BITNET

|\ /|  . Ack! (NAK, SOH, EOT)
{o O} . bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce
 (")
  U	"[The Amiga 1000 can display] up to 50 overlapping windows
	simultaneously." -Amiga Advertising, Spring 1987
	(Yeah, thats it... *understate* the machine's capability :-( )