Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!cs.utexas.edu!uunet!brunix!iris.brown.edu!mjv
From: mjv@iris.brown.edu (Marshall Vale)
Newsgroups: comp.sys.atari.st
Subject: Mega chips & drive questions
Message-ID: <21653@brunix.UUCP>
Date: 27 Nov 89 20:50:42 GMT
Sender: news@brunix.UUCP
Organization: IRIS
Lines: 48

I have several questions about chips in my Mega2. 

I've been thinking about upgrading to TOS 1.4 and have read the messages
 about the weak power chips. I looked in my Mega2 and here are the chip 
numbers in order of 1-4 going from top to bottom on the board:

Rev. 5.0 Mega2 (made in/just before April 89)
 1 - GD74LS244
 2 - T74LS373B1
 3 - GB74LS244
 4 - T74LS373B1

My Mega is running on a two rom set. I'm wondering if I should have these
 replaced when I get rainbow TOS.  The LS373's have a chip name of _ST_ .
  David Small mentions in the GCR manual that ones made by SCS are 
definitely bad, so are these LS chips also bad?

My current chips power the GCR just fine and even for extended periods of 
time too. 
Should I try to wait for the two ROM set which Ken B. said has been made
 or get the 6 rom set now?

I also noticed that there was a very tiny board on top of the 68000 with a 
_SCST74LS74B1_ in it and a wire running to an unlabeled spot on the 
board just above and to the left of the 68000.  Anyone know what its for?
 It seems like it was a rather last minute change and the glue job was
 very sloppy.

And a note to anyone who maybe interested; there are tracings on my board 
to the unused memory slots so it appears that I can upgrade to 4 meg. I
 compared my motherboard to the picture of the early Mega4 in STart a
 while back and they looked the same (except for the board on the 68000).
 I was not able to look at the MMU chip to check its ending letters (to see
 if it was one of the 2meg only kind) because I wasn't confindent about 
getting the bindings off. I'm not much of a hardware guy :-)

Has anyone else had problems getting the internal drive on Megas to work
with the GCR? What exactly did you do to fix it. I just would like a 
better description of proceedures that D. Small gave in the read me file. I
 sure am glad I have external SF314 to read those Mac disks, loud as it may be.

Thanks in advance!

-- mjv@iris.brown.edu

"And, oh! Father Christmas, if you love me at all,
 Bring me a big, red india-rubber ball."
                                   A.A. Milne "Now We are Six"