Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!gem.mps.ohio-state.edu!apple!marc
From: marc@Apple.COM (Mark Dawson)
Newsgroups: comp.sys.mac
Subject: Re: Mac IIci SIMMs
Keywords: fast page mode - what is this?
Message-ID: <35682@apple.Apple.COM>
Date: 16 Oct 89 14:55:48 GMT
References: <10730@phoenix.Princeton.EDU> <112@dfmp1.UUCP>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 55

In article <112@dfmp1.UUCP> lsanner@dfmp1 (Lou Sanner M.D.) writes:
>
>I am getting a IIci soon (hopefully) and I am trying to clarify three memory
>questions:
>
>1) Are the configuration rules for the IIci RAM banks DIFFERENT from the other
>Mac 68030 machines?  According to the Byte review, the IIci does not require
>contiguous memory installation.  Does this mean that I can mix and move memory
>around in the 8 SIMM slots?  Can I have a 3MB machine?  Can I have two 1MB
>SIMMS in the A bank and 2 in the B bank?  On the other 68030 machines the
>allowable memory configurations are 1-4-5-8 MB given the rules that "bank A
>must be filled", "bank B must contain 0 or 4 SIMMs" and "bank A must contain
>equal or higher density SIMMs than those in bank B".  What are the rules for
>the IIci?
>
    The only rule change between the IIcx && the IIci is that the IIci allows
    you (and I would recommend) to put more memory in bank B than in bank A.
    You still can only have 1, 4, 16, or 64mb in a bank (not 3mb, etc).  You
    can also leave bank A empty (you would need to use a video card if you
    did this, though).

>2) Will the IIci run more efficiently (faster) under Multifinder if I put
>"some" RAM in the A bank and "most" in the B bank.  According to the Byte
>review the video system locks out the CPU access to the A bank for 600ms when
>it refreshes.  Apparently Multifinder loads applications in the B bank first
>so these would not be slowed by this recurrent lockout.  What about when
>System 7 comes along - where should memory be then?
>
   Yes.  The built-in-video runs out of bank A.  If there is memory in bank B
   also, the IIci puts all programs, etc in bank B.  When you have used up all
   the memory in bank B, the IIci starts using the memory that the built-in
   video hasn't used.  So if you use MacsBug/TMON and look at address 0, you're
   really looking at the 1st part of bank B.  Note that this is done in the
   hardware, not the system software...system 7 should act just like any other
   application--loading into bank B first.

   Anytime your program uses or access bank A while built-in video is running,
   it will be slowed down (I'm not sure by how much).  My current configuration
   is 4mb in bank B, and 1mb in bank A.

    The addressing looks something like:

           bank B                      Bank A
    |xx                0|//|yy       xx+1| video RAM |

>3) Do I have to put 80ns RAM in the IIci?  We have a (growing) bunch of 120ns
>and 150ns 256K SIMMs here.  I suspect that I do have to use 80ns RAM... so
>where is a good source (price, reliability...)?
>

   You need to put 80ns FAST-PAGED RAM in the IIci (there have been some
   earlier articles on that).  Anything else will not work (or not work for
   long).

    Mark