Gather 'round, young 'uns: the 1998-vintage Powerbook G3 "PDQ" officially supported only 192 MB of RAM. Unofficially it was possible, if you bought the right DIMMs, to upgrade it to 512 MB. Which I did, just for laughs. (It was also possible, using XPostFacto, to upgrade it past the official OS X 10.2.8. maximum to 10.4.11. But it was so slow it was practically unusable.)