problem installing more memory

Verify the 256 stick works by trying it in someone else's computer.

And try removing the 128 stick and replacing it with the 256 and see if the computer picks it up.

While 99% of machines that are supposed to take PC100 will happily take PC133, there are a few that don't.  Is this machine any particular brand and model?

Your board is a slot 1 board, right?  What chipset?  440BX (common on many Slot 1 boards)?  Th 440BX chipset does not support most 256MB DIMMs.  You need Registered 256 MB DIMMs.  Tell us what make/model your computer and/or motherboard is and we can verify this is the case.

dbrunton - I tried removing the 128MB chip and replacing it with the 256MB and the machine failed to boot.

magarity - The machine is built by a UK company called 'Tiny'. Do you think it is worthwhile taking the chip back to the supplier and swapping for PC100 SDRAM?

leew - Sorry, I know very little about the internal workings of PC's so I don't know what board / chipset I have, and can't find any documentation. I could try contacting the supplier tomorrow (althought the machine is nearly 3 years old). What are Registered 256MB DIMMS?

Look on the motherboard for any signs of a model or brand.  I'm guessing this is a generic (built by some vendor someplace) computer and not a Dell, HP, Compaq, etc.

<This explaination cut and paste from Crucial's web site - www.crucial.com>
Registered modules contain a register that delays all information transferred to the module by one clock cycle. Like buffered modules, registered modules are typically used only in servers and other mission-critical systems where it is extremely important that the data is properly handled.

By the way, registered memory is more expensive and currently sells for a little over $71 on crucial's web site.

To help identify the motherboard etc.

BIOS  
http://www.motherboards.org/
or check the motherboard manufacturers website.
To ID it go to http://www.sysopt.com/mboard.html

I hope this helps !

I've just run the Belarc Advisor program from the Crucial web site and this is the info it gave me:

System Model : Micro-Star Inc. MS-6183
Board: Micro-Star Inc. MS-6183 1.0
Bus Clock: 100 megahertz
BIOS: American Megatrends Inc. 62710 05/20/99
128 Megabytes Installed Memory
Slot '0' has 128 MB
Slot '1' is Empty

The other thing about the Crucial site was that it listed most Tiny PC models and it seemed to suggest that they could only handle 2 slots of 128MB each

Whups, my bad counting.  It needs 256MB spread over 16 little chips.  16X128Mbits = 256MBytes.

Both sticks have 16 chips (8 on each side).

Could be that the module is not good. You either need to test it in another machine as has been mentioned known to be able to use a module like this or take or send it back to the vendor and get a replacement module.


The Crazy One

Yes, just to add to the above comment, test it in another new updated system. Make sure it works, seems you already have the chip density issue covered with Magarity.

Probably just a BIOS update away if the module is proven good.

Joe

I can't really get access to another PC (well not one that the owner would let me take the lid off) so I guess I'll take it back to the supplier on Monday. Maybe they can test it.

Joe - what did you mean by BIOS update?

Is the general concensus that the memory is faulty?

Well I've taken the stick back to the vendor and have ordered some PC100 SDRAM from Crucial. Points to magarity for providing the most help