Path: utzoo!mnetor!uunet!cbmvax!grr
From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga 1000, and Micron Technologies single slot chassies
Message-ID: <3019@cbmvax.UUCP>
Date: 27 Dec 87 21:53:12 GMT
References: <8712250110.AA26008@jade.berkeley.edu> <3315@ulysses.homer.nj.att.com>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 71

In article <3315@ulysses.homer.nj.att.com> eric@hector (Eric Lavitsky) writes:

> Don't understand why you did this - the Micron memory board is way superior
> to the Commodore design (no offense guys :-), because of the following:

	Eric, Eric, your board may be "better" than our board, but let's keep
	the advertising hype down.
 
> 	1) 4 layer PC board (CBM is two layer) - means less noise
> 		on the bus. *I'll* guarantee you that 4 Micron boards
> 		will work in a B2000 (won't speak for ther Germans!)

	It means less noise on the *board*, not necessarily less noise on
	the bus.  It makes the boards more expensive, but might be worth
	it in a marginal situation.  BTW, the memory boards were designed
	here.

> 	2) Socketed RAM array (CBM is soldered) - means bad chips
> 		are easily replaced.

	This is a religious issue.  It is generally considered that while
	sockets make boards easily repairable, their presence, especially
	in the quantity you have in a memory board, is a detriment to
	overall system reliability.  If I have to repair a system that
	has chips in sockets, the very first thing I do is shove all the
	chips into the sockets and try again.

> 	3) Full diagnostics (CBM comes w/none) - means that you can
> 		determine which chips if any are bad.

	A worthwhile investment.

> 	4) Long warranty (two years I think)

	Also nice.
 
> 	5) The Micron board (ASDG's design) is a superset of the
> 		Zorro board specification. It provides full Zorro
> 		bus buffering and arbitration on the board. Because
> 		of this, the Micron/ASDG memory board will work in
> 		just about any Zorro or Zorro subset box around.
> 		The ASDG MiniRack-C was a Zorro subset box; the Micron
> 		single slot adapater is a Zorro subset. The CBM board
> 		expects to be plugged into a *full* Zorro backplane.

	A bunch of mumbly-poo that basically allows as the first ASDG
	expansion chassies designs were non-standard, but their memory
	boards were clever enough to swing both ways.  This is fine and
	well, but implies that expansion devices designed only to
	support their boards, may not work with a standard board...

	Note that there are no defined Zorro "subsets" or "supersets",
	these are simply ASDG labels for what the decided to implement.
	We have an 86-pin expansion connector and a 100-pin expansion
	connector.  The exact characteristics of the connectors differ
	in what are hopefully non-critical ways between systems.
 
> Sorry to hear it, but there's not much you can do. If you can return the
> CBM board and get a Micron board (I hear Able has it for under $350.00),
> I'd recommend doing that.

	Not altogether bad advice.  Generally, avoid mixing apples and
	oranges unless you understand the consequences or have some
	independent assurance that the combination works.  One could of
	course keep the A2052 board and obtain an A2000 or some "Zorro
	standard expansion device.

-- 
George Robbins - now working for,	uucp: {uunet|ihnp4|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)