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Maximizing memory on my Centris 650 - will this work?

Phipli

Phipli

Well-known member
1200XL M.U.L.E. said:
So, if I install these modules one by one in my Centris 650, then I should see my available memory grow by 64MB each time.
Click to expand...
Yes.

Also the machine supports interleaving, so having memory installed in like pairs gives a small number of percent speed improvement.
 
1200XL M.U.L.E.

1200XL M.U.L.E.

Well-known member
My four sticks of memory arrived today. I installed them one by one and watched my total available memory climb by 64MB with each stick added. My machine now has a whopping 256MB of RAM. I could not imagine this number on any machine in 1994. I think my 486 system back in the day used to have 8MB and then 16MB and I felt like a god with that much RAM.

IMG-3617.jpg

Now I understand the longer boot time. My Centris just sits there after the chime, not displaying anything. This must be the memory test. After the memory test is over, the monitor comes to life and slowly warms up. Then I see the welcome screen and the extensions start loading. At first this freaked me out. Seeing nothing is scary!

I'm not sure what I'll do with 256MB of RAM 😄 but I'll have it ready when I need it.
 
Phipli

Phipli

Well-known member
1200XL M.U.L.E. said:
My four sticks of memory arrived today. I installed them one by one and watched my total available memory climb by 64MB with each stick added. My machine now has a whopping 256MB of RAM. I could not imagine this number on any machine in 1994. I think my 486 system back in the day used to have 8MB and then 16MB and I felt like a god with that much RAM.

View attachment 52464

Now I understand the longer boot time. My Centris just sits there after the chime, not displaying anything. This must be the memory test. After the memory test is over, the monitor comes to life and slowly warms up. Then I see the welcome screen and the extensions start loading. At first this freaked me out. Seeing nothing is scary!

I'm not sure what I'll do with 256MB of RAM 😄 but I'll have it ready when I need it.
Click to expand...
Glad everything worked out :)

Does your 650 board have the ROM slot fitted, or is the location unpopulated?
 
Phipli

Phipli

Well-known member
1200XL M.U.L.E. said:
My board looks just like your picture. There is nothing there. What was the ROM slot for, if it were to be installed?
Click to expand...
Apple tended to include a ROM SIMM slot on early machines of a model (or all of them on older machines). It meant if they messed up they could send out physical ROM updates. A ROM SIMM fitted there overrides the onboard one. You can modify the stock ROM, put it on a SIMM... and install it. One such mod is to disable the RAM test...

Another is to make it recognise 128MB SIMMs! I believe it gets upset if you install more than 128+128+64+32+8... 360MB if I remember.

This might... be a project for the future. Soldering in slots and making custom ROMs is probably for the second month of Mac ownership 😆
 
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