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Path: utzoo!watmath!clyde!rutgers!ames!amdahl!kim
From: kim@amdahl.UUCP
Newsgroups: comp.sys.amiga
Subject: Cheap ram expansion mods
Message-ID: <5206@amdahl.UUCP>
Date: Sat, 17-Jan-87 08:11:00 EST
Article-I.D.: amdahl.5206
Posted: Sat Jan 17 08:11:00 1987
Date-Received: Sat, 17-Jan-87 16:51:52 EST
Organization: Amdahl Corporation,  Sunnyvale, CA 94086
Lines: 50
Keywords: hardware ram expansion modifications


[ "Send lawyers, guns, and money ..." ]

The new issue of Amazing Computing (v2,n1) has a very detailed article (by
Cris Erving) about how to add 512K of memory to the Amiga's motherboard.
Of course it involves a bit of h/w hacking, and would certainly void one's
warranty, but the cost is only about $70 for parts.

Because of the address space where it lives, just above Chip ram in part of
the "reserved" address space, it won't AutoConfig ... you have to use AddMem.
And no, you can't use it as Chip memory, because the custom chips can only
address the lowest 512K ... AmigaDOS sees it as Fast ram (though unlike
expansion bus Fast ram, there *can* be contention with the custom chips
for memory accesses within this 512K).  Cris gives the name "Synchronous"
to this kind of ram.

The article also says that there is enough power left over to run things
like Digi-View, or A-Time.  I'm wondering if there would be a problem with
having a C.Ltd 1 Meg aMEGA board on the expansion bus, power-wise?  Anyone
know if there's a heavy-duty replacement power-supply that has the same
form-factor as the original?

Also, I'm wondering if this mod can be made compatible with the "Kickstart
Eliminator and RAM Expansion Kit" by Creative Microsystems, Inc. that
Jac Colby talked about in a recent posting.  This mod wants to live at
x'080000' thru x'0FFFFF', immediately above Chip ram.  [Jac ... where does
the WCS end up living after installing the Kit?  Can it be moved elsewhere?]

Assuming the Kit and the mod can be made to co-exist addressing wise, there
shouldn't be a problem power-wise, as the Kit is only adding 2 ROM's to 
what's already there.  Lesee, that would be an extra 768K for about $200,
and a few hours work ... not bad!

Of course when the Amiga XXXX (where XXXX is your favorite rumormill number),
comes out with the Fat-Agnus chip that can address 2 Meg, these are in the
address space she'll want.  But then you can't put a Fat-Agnus into an
Amiga 1000 ... or can you ... hmmmmm?

/kim


-- 
UUCP:  kim@amdahl.amdahl.com
  or:  {sun,decwrl,hplabs,pyramid,ihnp4,seismo,oliveb,cbosgd}!amdahl!kim
DDD:   408-746-8462
USPS:  Amdahl Corp.  M/S 249,  1250 E. Arques Av,  Sunnyvale, CA 94086
CIS:   76535,25

[  Any thoughts or opinions which may or may not have been expressed  ]
[  herein are my own.  They are not necessarily those of my employer. ]