Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!seismo!husc6!mit-eddie!uw-beaver!tektronix!sequent!mntgfx!dclemans
From: dclemans@mntgfx.MENTOR.COM (Dave Clemans)
Newsgroups: comp.sys.atari.st
Subject: Re: DLII.ARC (really 4 megabyte ST's)
Message-ID: <810@dclemans.mntgfx.MENTOR.COM>
Date: Fri, 17-Jul-87 12:58:13 EDT
Article-I.D.: dclemans.810
Posted: Fri Jul 17 12:58:13 1987
Date-Received: Sat, 18-Jul-87 19:39:50 EDT
References: <736@ektools.UUCP> <67@laura.irb.informatik> <798@dclemans.mntgfx.MENTOR.COM>
Organization: Mentor Graphics, Beaverton OR
Lines: 30
Summary: about 4 megabyte ST's

Someone asked a question about taking an ST to 4 megabytes, so here goes:

To get to 4 megabytes, I installed an Aerco memory board into my ST (the Aerco
board is also what is distributed by the E. Arthur Brown mail-order company).
If it's relevant, I have a very early ST (with a rev A board).

The Aerco board can be used to take a 520 to 1 megabytes, 2.5 megabytes or 4
megabytes.  Going to 1 or 2.5 megabytes everything is solderless; to go to 4
megabytes requires significant soldering on the memory daughter board, but
no soldering to the ST itself.

The Aerco board connects to the ST at three points.  First, the MMU chip is
removed from it's motherboard socket, and placed in a seperate socket on
a small piggyback board.  That piggyback board then plugs into the mmu socket,
and also to the memory daughter board.  The memory board connects at two other
points to the ST mother board, using clips that fit over two data bus buffer chips.

Provided that the 1040/520STFM board layout uses the same two buffer chips to
handle the memory data lines, and those buffer chips are in approximately the
same relative location to the mmu socket as on the 520ST motherboard, the
Aerco memory board could also be used on the 1040/520STFM.

To be able to reach 4 megabytes without doing any soldering on the ST's motherboard
changes are made on the piggyback board mentioned above so that none of the control
signals from the mmu that are meant to go to the ram array reach the motherboard;
they only go to the memory daughter board.

The board has worked very solidly for me.

dgc