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			<title>Macintosh LC: RAM Configurations and Limits</title><body class="ac-gn-current-support">
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<h1 id="main-title">Macintosh LC: RAM Configurations and Limits</h1>
<div id="abstract">
 
<div id="intro-container"><div class="truncate"><div class="attr SYMPTOMS"><div class="attr TOPIC"><FONT SIZE=4><BR>
What is the maximum amount of memory possible in the Macintosh LC?  Is<BR>
10MB an absolute limit?  Will a future Macintosh LC be able to use 34MB<BR>
with the addition of two 16MB SIMMs?<BR>
<BR>
</FONT></div></div> <!--  attr Symptom  --></div> <!--  truncate --></div> <!--  intro-container --><div class="clear"> </div>
 </div>   <!-- abstract end -->
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  <div class="attr SUMMARY">
There is a limit of 10MB of RAM on the Macintosh LC when running under<BR>
System 7.  It will not be possible to use 16M SIMMs to achieve 34MB.  This<BR>
is because the memory map for the Macintosh LC reserves only 10MB of<BR>
address space for RAM, regardless of if it is in 24-bit mode or 32-bit<BR>
mode.  The memory map is as follows:<BR>
<BR>
    Function              24-bit mode               32-bit mode<BR>
    --------              -----------               -----------<BR>
    RAM                   $00 0000-$9F FFFF         $0000 0000-$009F FFFF<BR>
    ROM                   $A0 0000-$DF FFFF         $40A0 0000-$40DF FFFF<BR>
    Expansion space       $E0 0000-$EF FFFF         $FE00 0000-$FEFF FFFF<BR>
    I/O space             $F0 0000-$FF FFFF         $50F0 0000-$50FF FFFF<BR>
    VRAM                  $FC 0000-$FF FFFF         $50FC 0000-$50FF FFFF<BR>
<BR>
<BR>
It is also not possible to use 256K or 512K SIMMs.  The possible RAM<BR>
configurations, using 1MB, 2MB, and 4MB SIMMs, for the Macintosh LC are:<BR>
<BR>
    2MB  -- soldered on the motherboard<BR>
    4MB  -- add two 1Mbit SIMMs in each of the SIMM connectors<BR>
    6MB  -- add two 2Mbit SIMMs in each of the SIMM connectors<BR>
    10MB -- add two 4Mbit SIMMs in each of the SIMM connectors<BR>
<BR>
The Macintosh LC requires 100ns or faster SIMMs.<BR>
<BR>
<BR></div>
</div>


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<div class="mod-date">Published Date: Feb 18, 2012</div>
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