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From: pete@wlbreng1.UUCP
Newsgroups: comp.sys.m6809
Subject: Re: 512K and wimpy GIME chips
Message-ID: <172@wlbreng1.UUCP>
Date: Mon, 16-Feb-87 11:38:42 EST
Article-I.D.: wlbreng1.172
Posted: Mon Feb 16 11:38:42 1987
Date-Received: Thu, 19-Feb-87 07:22:21 EST
References: <1404@ihwpt.UUCP>
Reply-To: pete@wlbreng1.UUCP (0000-Pete Lyall)
Organization: Eaton Inc. IMSD, Westlake Village, CA
Lines: 60

In article <1404@ihwpt.UUCP> knudsen@ihwpt.UUCP (mike knudsen) writes:
>I bought a blank PBJ upgrade daughter board for my Coco III
>and put my own chips in it.  Like, three different brands--
>Western Electric, TI, and some Korean outfit.
>It hardly worked at all.  I had more Korean chips so I
>made it all Korean (they should feel at home in there ;-) ).
>Now it almost works -- fine as a Coco II, but usually
>screws up if it tries to print much in WIDTH 40 or 80.
>Not looking forward to running OS9-L2 on this....
>
>The failures were "analog" in nature -- the more RAM chips
>I replaced with Korean, the better it worked.
>From this I conclude that some RAM chips must load down
>(draw current from) the address and control (RAS, CAS)
>and data lines than others.  All these chips are 150 ns
>(the PBJ instructions say to use 120ns, but their populated
>boards come with 150 chips anyway!)
>
>Originally the GIME chip must drive only 4 chips worth of
>address & control, but you multliply this by 4x when you
>upgrade.  So I suspect the GIME, which uses wimpy (non-TTL)
>CMOS logic, can't drive all those inputs.
>
>Unless you're careful to use exactly the right make
>& model of RAM chips.  Anyone got any recommendations?
>BTW, the power supply regulator (big heat sink) gets pretty
>toasty.  I intend to 'scope out the +5V supply to make
>sure there's no ripple.  And of course to view the signal
>leads as well.
>
>Cuda been worse -- I cuda soldered all those chips piggybacked
>onto my DISTO Ramdisk (which works great, BTW).  Or onto
>an Atari 520ST... ... mike k
>-- 
>Mike J Knudsen    ...ihnp4!ihwpt!knudsen  Bell Labs(AT&T)

I have heard (from the product manager and Steve Bjork..) that the
system requires either 150 NS >NEC< Drams, or 120 NS of any other
kind. I have taken no chances and installed 120 NEC's.

On another tack, has anyone else noted the 'snowflake effect' under
level II? It seems to be that re-mapping of memory by the gime cause
little white spots to appear on the monitors (all - I have tried 3
RGB's and 2 monochromes). It is very prominent under applications that
use a lot of system calls (like I$getstt in a terminal program)..

BTW - Level II was cleared through Q/A as of Tuesday of last week..

Pete


-- 

                                                   Pete Lyall

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