Path: utzoo!utgpu!watserv1!watdragon!tiger!mwandel
From: mwandel@tiger.waterloo.edu (Markus Wandel)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Writing to WCS
Summary: Trivial
Message-ID: <20011@watdragon.waterloo.edu>
Date: 20 Jan 90 20:01:49 GMT
References: <90012003501244@masnet.uucp>
Sender: daemon@watdragon.waterloo.edu
Reply-To: mwandel@tiger.waterloo.edu (Markus Wandel)
Organization: U. of Waterloo, Ontario
Lines: 44

In article <90012003501244@masnet.uucp> david.evans@canremote.uucp (DAVID EVANS) writes:
>
>  I realise this falls into the "weird stuff", and probably "heavy 
>magic" catagory, but how do you enable the WCS on the A1000 for writing?

Run the following through any assembler and Blink:

		lea     bootcont,a0
		move.l	a0,$80
		trap	#0
bootcont:
		move.l	$fc0004,a0
		jmp	-2(a0)
		end

Then wait for all disk updates to complete and run it.  Poof, Amiga reboots
with WCS accessible for writing.

Works by kicking the CPU into supervisor mode (using the TRAP instruction),
then fetching the address where the CPU would normally begin running the
kickstart code at.  Like magic, in both 1.2 and 1.3 there is a "RESET"
instruction directly before this code, so that's where we jump to.

What happens is that all hardware in the machine gets reset except the CPU.
Autoconfigured memory vanishes, chip memory goes poof, but the WCS stays
around and so the 68000 goes on running.  It goes through a standard boot
up, reconfiguring autoconfig memory and all other hardware, but *not*
write-protecting the WCS, as this apparently gets done by the ROMs which
do powerup diagnostics and load the Kickstart disk, which have been
bypassed in this case.

If you boot from floppy anyway, just find someone who has AMAX and get them
to run the "BootBlockRestore" program on your boot disk.  This creates a
boot block which does the same thing, so your machine *always* has the WCS
enabled when booted from that disk.

Disclaimer:  The above is not BY ANY MEANS a supported standard programming
             practice on the Amiga.  It works now.  It depends on the "RESET"
             instruction in Kickstart.  If it goes away with 1.4, it won't
             work any more.

Markus Wandel
mwandel@tiger.waterloo.edu
(519) 884-9547