Path: utzoo!attcan!uunet!uvm-gen!pegram
From: pegram@uvm-gen.UUCP (Robert B. Pegram)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: Upgrading Mega 2 to 4.
Message-ID: <1672@uvm-gen.UUCP>
Date: 1 Oct 90 19:10:56 GMT
References: <1599@kielo.uta.fi>
Sender: news@uvm-gen.UUCP
Organization: EMBA Computer Facility, Univ. of Vermont, Burlington.
Lines: 49

From article <1599@kielo.uta.fi>, by jackin@vehka.uta.fi (Markku M{enp{{):
> I have a Mega ST 2 which I am planning to update to 4 MB.

> I have now 16 empty sockets available, but putting 80ns
> chips didn't work. It was quite expectable original chips
> being 150ns.

> Do 120ns chips work or do I need 150ns (rare in 1MB chips) ?

Yes, they should work, I have 100ns chips in my expanded 520.
80ns may be pushing the refresh rate, but I haven't looked into it.
I believe there was a note about it on c.s.a.st last year.

> Is there anything else to do apart putting chips in and 
> soldering capasitators (as is done in original 2 MB) ?

I hope someone else expands on this as I can only suggest things from
possibly faulty memories (my own, not the ST's 8-).  1) You need to
have all the correct resistors in place for things to work.  2) I seem
to recall that Atari sent out some Mega 2s that have faulty MMUs, i.e.
they can only handle 1 bank instead of the regular 2.  The numbers of
these chips are known, and I might be able to dig the article up (US
ST World I believe) if no one else can elaborate on this.  If you want
to do something about this *now*, and have access to a working Mega 4
or upgraded Mega 2, open it up and note the MMU numbers and look for
resistors (RAS, CAS, etc. for bank 2, there are plenty of them I
believe) that are not in your Mega.  Add any missing resistors
(correct values and tolerances please, just match the color codes or
markings) and if it still doesn't work, swap MMUs.  BTW, does it still
work properly with 2Meg?  In any case, please check your soldering
again for bad (cold) solder joints and for "bridged" traces.

> I wanna see my Spectre work with 4MB !!!!

Me too, but I need a Spectre 1st, then the new memory board and xtra 2 Meg 8-).

> Thanks,
> Markku

> --
> Markku M{enp{{ 
> email : jackin@vehka.uta.fi
> phone : 358 31 561 575 (in Finland (931) 561 575)

Good Luck,
	  Bob Pegram

Internet domain: pegram@griffin.uvm.edu
UUCP: uunet!uvm-gen!pegram