Scott Holder wrote:
> urquidez wrote:
>> Hello all. Just upgraded from 8mb to 20mb. New ram shows up in "about
>> this mac..." but now the system is using a whopping 15mb! With all
>> extensions off it's still using around 12mb. Sense not this makes.
>> Anyone have any idea?
>> SE/30
>> 7.5.5 freshly installed before the new RAM arrived
>> All 7.5.5 extensions on or off.
>>
>> Tia, ju
>
> This is the classic 24 vs. 32 bit issue.
>
> Go to Apple -> Control Panels -> Memory and switch it to 32 bit
> addressing. Should clear it right up.
>
> Note that on the off chance you're using something that requires 24 bit
> addressing, you'll have to switch it back and lose the extra RAM.
That 12Mb isn't being used, it's just that the system can't use more
than 8Mb under 24 bit addressing so it shows any excess as "used".
If you don't have the option of enabling 32 bit addressing in the Memory
CP you need to install a piece of software called "Mode 32". Macs
before the IIci had ROMs which didn't work with 32 bit addressing. Mode
32 patches the ROMs so you can use more than 8Mb.
If you do the math 24 bit addressing is 16Mb of address space. That
space is allocated thusly:
8Mb RAM
1Mb ROM
1Mb for logic board I/O
1Mb per NuBus slot for up to 6 slots, or 1 PDS slot used in the SE/30.
Memory is still allocated for 6 slots.
--
Clark Martin
Redwood City, CA, USA
Macintosh / Internet Consulting
"I'm a designated driver on the Information Super Highway"
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