The Apple G3 Yosemite "Blue and White" and its G4 Yikes and original Sawtooth "Graphite" variants have four SDRAM expansion slots. No memory is soldered to the logic board, so at least one DIMM must be installed for these machines to boot. Apple does recommend that DIMMs be installed in slot 1 first (J19), then in J20, J21, and J22, in order. As the Grackle IC memory controller and PCI bridge on the Yosemite/Yikes and the Uni-North memory controller on the Sawtooth logic board support only linear memory organization, no benefit accrues from installing SDRAM DIMMs in matched pairs, and DIMMs (installed in any slot and any order) are addressed as a contiguous memory array. Originally, the max memory installable in Yosemite/Yikes/Sawtooth was 1GB, in the form of four (4) 256MB 128Mbit pieces. With the release of G4 Firmware Update 2.4 (5-26-2k), memory configurations up to 2GB are physically conceivable in original Sawtooth using four (4) 512MB SDRAM DIMMs. Due to limitations in MacOS 9.04 and OS9.1, the max memory configuration useable at this time is 1.5GB. No, we have not yet tested in all possible configurations in all machines. In fact, we just recently confirmed that it is not possible to run a Yosemite or Yikes with memory beyond 1GB. The densest pieces that work in Yosemite and Yikes--and yes, Beige G3--are 256MB. We have confirmed the 1.5GB limitation in Sawtooth G4 500 under MacOS9.1 with Firmware Update 2.4 using three 512MB SDRAM DIMMs. Reports from the field are welcome.
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