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From: mks@cbmvax.commodore.com (Michael Sinz)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 4 meg ZIPS=3.5 megs installed?
Message-ID: <22495@cbmvax.commodore.com>
Date: 17 Jun 91 13:14:05 GMT
References: <8476@oasys.dt.navy.mil>
Reply-To: mks@cbmvax.commodore.com (Michael Sinz)
Organization: Commodore, West Chester, PA
Lines: 28

In article <8476@oasys.dt.navy.mil> lapeyre@oasys.dt.navy.mil (J P Lapeyre) writes:
>Hi, I recently installed 8 1Megabit x 4 bit Zips into my 16/50 A3000
>and moved the 256Kx4 dips  into chip memory. I installed the  zips into
>bank 0 and when I rebooted my A3000 shows 2 meg chip memory and 3.5 meg
>fast RAM. I've checked and rechecked all pins but can't see any probs.
>I removed one chip and the machine wouldn't even boot. Anyone know
>why my system doesn't show 4 megs of fast RAM? The 3.5 worth all checks
>out fine. That's my dilemma, the other 0.5 meg doesn't even show up
>so, how can I test it?

The other 512K is currently being used by the system to load KickStart.
Kickstart on the A3000 is loaded into RAM via some magic in the current
A3000 ROM.  This magic removes 512K of RAM from the system and places
Kickstart there.

When/if you ever upgrade to ROMs you will get the 512K back but you
may also wish to used it again with CPU FASTROM since the RAM chips
(and SCRAMs even more so) are much faster than the ROM chips.

			-- Mike

/----------------------------------------------------------------------\
|      /// Michael Sinz  -  Amiga Software Engineer                    |
|     ///                   Operating System Development Group         |
|    ///   BIX:  msinz      UUNET:  rutgers!cbmvax!mks                 |
|\\\///                                                                |
| \XX/     "I don't think so" said Ren'e Descartes, then he vanished.  |
\----------------------------------------------------------------------/