Critical Software Systems
Technical Information

An 800MHz Pentium 3 notebook, on the market in the 2000 timeframe.

The biggest "gotcha" with this laptop is one shared by many Sony VAIOs.  That is, the second memory expansion slot can stop working due to a bad mechanical interface.  I had a 128MB SODIMM in this slot installed when I bought the PC, and then recently (2004) upgraded that to 256MB (with the other slot also at 256MB, taking the PC to its maximum of 512MB).  The RAM in the second slot wasn't recognized. 
A search of Usenet turns up the common fault - the socket doesn't make a good connection unless there's additional pressure put on it.  If you're installing memory in the second slot and it's not being seen, you can hold your fingers on the SODIMM (being grounded of course) as you boot the computer.  If this works, proceed to make the "permanent" fix, which is to put something between the SODIMM and the memory slot cover that will permanently apply pressure to the chip & socket. 
The preferred material is shrink wrap tubing - no need to actually shrink it onto anything; simply cut a few short pieces and lay them on the SODIMM.  Then, as you screw the memory slot cover back on, they will press the chip firmly into the socket, and your memory should be seen each time the PC is booted.
Note also that there's a special type of SODIMM required for this laptop - I'm using the Kingmax 16-chip PC133 SODIMM.  The 8-chip design does not work in the VAIO.  Each slot will accept a maximum of 256MB for a system total of 512 MB.
The best prices and support for memory I've found on the web are at

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