32mb showing up as 18mb

Hello. I just picked up an mpc2000xl. It needed a new screen and couldn’t see how much ram was installed until I opened it up. It has a single 32mb stick in a lot 1. I reseated it after removing and cleaning and when I check it says it has 18mb. Is my stick actually just a 16mb or is there something else that could be the problem

I did reseat it, idk why pics don’t work just shows the ram, ram in slot one , then the Mac screen showing only 18 mb

I suspect that each memory slot only recognises a maximum of 16mb ram, all the upgrade kits on eBay come with two chips.

So currently you effectively have 16mb on one slot and the original 2mb (which gets replaced when you add a second 16mb ram chip to give you 32mb)

MPC-Tutor wrote:I suspect that each memory slot only recognises a maximum of 16mb ram, all the upgrade kits on eBay come with two chips.

So currently you effectively have 16mb on one slot and the original 2mb (which gets replaced when you add a second 16mb ram chip to give you 32mb)

Slot one can take 32mb in a single stick according to the manual

In the mpc1000, for third party ram you always had to buy a ram stick that was twice the size (256 to get 128). Not sure if this is a similar issue, I see those eBay listings are the XL are showing 2x32 sticks

Rabbigolem wrote:Slot one can take 32mb in a single stick according to the manual

The manual is wrong.

Get another stick of ram Rabbi.

richie wrote:

Rabbigolem wrote:Slot one can take 32mb in a single stick according to the manual

The manual is wrong.

Get another stick of ram Rabbi.

Thanks man, should I get two matching 16mb then?

I don't know about the 2k, but I know the 1k/2.5k/500 could only read one side of the memory for some reason... it's possible the 2k is doing the same thing.

Your best bet is probably to get a pair of chips, just so you don't end up with CAS latency mismatches. I don't know enough about the 2k though to say whether you should get 2x 32mb or 2x 16mb.

Good luck either way!

Just pick up 2 identical modules from the same manufacturer, 2x16 MB recommended.
(in those days there were no „matched pairs“)

There might be 32MB versions available, but these are extremely rare and way more expensive.
Such modules had only 1 side with chips, each chip twice the size of the „regular“ version.
They were rather late implementations of EDO RAM, soon to be replaced by DDR.
Iirc one could use them to extend pre-PowerPC Macs to unusual memory amounts.
This does not mean the same applies to the MPC2K, it depends on address decoding and OS support, in other words: hardware and software.
Imo really not worth the gamble (you have to buy 2nd hand)

Just to be a bit more clear:
Considering you plug a single side 32MB Simm in and the display shows 32MB installed.
This is no indication, that the OS can address beyond 16MB in a single slot.
You‘d have to fill up memory and check if the first samples still exist because memory may overflow and start again at zero. Megabytes 17 to 20 may fill MB 1 to 4.

Exactly this happened frequently with certain disk controllers, when a drive „too large“ was installed
Of course there is a tiny chance it does work, but with 2 slots the chance that the OS will handle memory beyond 32MB is essentially zero, as the 2MB of the motherboard are hidden when both slots are filled.