View Full Version : RAM type and installation

07-09-2001, 03:32 PM
I have G3 266 desktop, Rev.1. A few days ago I installed Encore G3/500 processor card. Now, questions about RAM and slot sequence. I hope they are not too simple or naive for this forum.

Three 128 MB modules: two labeled 133mhz, and the other no label, but invoice said 10NS.
1. Does 10NS mean PC100 and does 133mhz mean PC133 and 8NS?
2. Can the three modules coexist peacefully and continue functioning? So far everything seems fine.
3. Does it matter which order the three modules are inserted?
4. Should the slowest (10NS) go into J3 or J5?
5. Which slot is used first: J3 or J5?
6. Does it makes sense to insert the faster modules in such manner that they are used first?
7. By "used first", I mean loading order. I figure system loads first, but into which module? If my Mac shows that I am using only 200MB, does it mean that one module is idle (empty)?
8. Will substitution of one 128 by 256 (PC100) result in longer start-up time? Longer boot-up time?

07-09-2001, 05:31 PM
1. No, 10ns (nanoseconds) does not necessarily mean PC100. Normally you want some leeway in the spec. 10ns should normally be PC66, but if its on spec - 10ns should run at up to 100Mhz. Apple PC100 spec calls for 8ns/125Mhz, some cheap PC 100 specs call for 9ns/~110Mhz.

2. As long as they are up to spec your system should be fine. Its normally better to get parts that are over spec even though you wont see any direct benifit, but you could still have PC133 that has other specs that your system does not like. Sounds like everything is fine.

3. No.

4. It does not matter. Your bus is 66Mhz, 83Mhz max (if you overclocked it).

5. Dont know.

6. Again, your system will not be able to use the extra speed in the faster models. The main benifit is that they are easier to get and cheaper than PC66 - you can then also take them to a P133 Mac (or possibly PC) the next time you upgrade.

7. I would guess that the lowest number 'J3' is used first. Your mac should show 384MB of installed RAM. How much is used depends on what software you are running and how much RAM you give that software. Also over time the system heap (memory) and application memory can grow.

I do not think that the Mac uses memory in a linear manner. At least when I run MemMapper it shows some memory (system heap?) taking up the last few MB of space and the App/finder memory taking up the lower portions. I suppose its even possible that your system could be using the first 128MB and the last 128MB, but not the middle. Not sure if MemMapper is literla, correct or accurate. It does report the amount application memory correctly.

8. Yes, normally since the Mac checks (I assume ALL) the RAM on startup. 768MB is the max you can install in this old mac. My PTProG3/500 starts up (from the time I hit the power on button) in about 1:45. It has 480MB of 60ns (17Mhz) RAM, but the fast 500Mhz CPU really speeds things up.

Not sure what you do, but you would probably see a bigger speed increase by installing a fast ATA/100 drive. You may need to get a PCI IDE/ATA 66 card because you have REV1, but the stuff it pretty darn cheap and it might even work with X. ! http://macgurus.com/infopop/emoticons/icon_smile.gif

07-09-2001, 08:31 PM
dragon_x: thanks for replying so fast. It was very helpful. Simple arithmetic says 100mhz = 10NS/cycle.
So, I thought there is a connection here.

I didn't mention that I do have IBM 75GXP Deskstar 45GB ATA100 as my main drive installed last year.
Next week I will be installing second IDE drive, IBM 75GXP Deststar 60GB ATA100 in the upper bay
(my G3 has ZIP installed). And yes, I have bought Sonnet ATA66 PCI for this second IDE drive.

Also, I have OrangeMicro Firewire/USB2 card. Total boot-up time (including the start-up) is 1 min 15 sec.
Thanks for telling what your delay is. I thought mine was long, but apperently it is ok. I am hoping that
Sonnet card and second drive will not prolong the total boot-up time significantly.