Path: utzoo!attcan!uunet!sco!brianm
From: brianm@sco.COM (Brian Moffet)
Newsgroups: comp.sys.amiga.hardware
Subject: Amiga 1000/ AmigaOS 2.0 / Expanded Memory
Message-ID: <7102@scolex.sco.COM>
Date: 12 Jul 90 15:10:54 GMT
Sender: news@sco.COM
Reply-To: brianm@sco.COM (Brian Moffet)
Organization: The Santa Cruz Operation, Inc.
Lines: 39



Could someone explain to me why the expansion memory to be used
for Amiga OS 2.0 has to be the first item on the bus (on a 1000)?

I looked through the ancient hardware manual at the autoconfig
stuff, and I thought that autoconfig, in this case, would allow 
any expansion memory on the bus be able to be used for the extra
memory space.  The reason for my thinking is:

the first device gets the signals stating that auto-config is happening.
	it does not pass this onto the rest of the devices.
  It passes back information about the card which tells where in 
  memory space it is (or does the amiga tell it where is free?)
  and the amiga OS remembers this.

the first device then passes on the autoconfig signal to the next
  device.  The second device follows the same procedure
  as the first autoconfig device.

I imagine that the amiga tells the device where it has to sit in
memory space upon finding out how much space is required.

So, why does the memory that KS 2.0 going to be loaded into
have to be the first thing on the bus?  Is there a sort of
bootstrap _'?b7going on where a very small section of KS 2.0
(enough to know how to deal with only 1 device is loaded)
is used, and then as soon as it knows about the memory, it loads
the rest into core and lets the major program take over the
auto-config?  If the bootstrap scenario is the case, what would be the
problem with making the bootstrap code understand more than 1
device on the bus?

thanks for your attention.

brian moffet
-- 
Brian Moffet	ext 3567	Mission St _"_e_n_o_u_g_h_ _s_a_i_d_" -- _e_r_i_c_h_i
"Do you do DRB?"  --  anonymous meeting scheduler