Power Computing PowerBase-series


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The PowerBase, like the related Performa 6360 and Power Mac 5400, boasts a 32-bit PCI bus architecture and a 64-bit memory bus. With three (3) DRAM DIMM slots handled by a PSX memory controller, this Alchemy variant requires JEDEC-standard 5-volt, 64-bit, 168-pin, buffered Extended Data Out (EDO) 60ns DIMMs, which must refresh at a rate of 2k or better. FPM memory is not compatible, and should not be installed in this machine under any circumstances.

Power Computing technical documents stress that EDO DIMMs installed in slot 1 (Bank 0, identified by board reference J15 above) must be single-banked, and 32MB in density, or less, while EDO DIMMs installed in slots 2 and 3 (board references J12 and J11, respectively) may be either single or double-banked pieces in densities up to 64MB.

Typically shipping with a single 16MB DIMM installed in slot J15, additional memory may be installed in either slot J12 or J11, in any order, as the PSX memory controller supports linear memory organization only, and cannot interleave. No performance benefit whatsoever derives from installing DIMMs in pairs in this machine.

The maximum amount of usable memory in the PowerBase-series is 160MB, in the form of two (2) 64MB EDO DIMMs in slots J11 and J12, and one single-banked 32MB EDO DIMM in slot J15.

At the present time, the only working 1MB L2 cache available for the PowerBase-series is IDT's 160-pin 512k L2 module which is fully compatible with all Alchemy-based variants, including the PowerBase-series. Performance gains between 256k L2 and 512k L2 are similar to those observed in other models of Power Macintosh: on the order of 8-15% systemwide.

Specifications
Logic Board RAM		8MB.
Supported DIMMs		32MB, 64MB.
Number DIMM Slots		Three (3).
Supported VRAM		2MB or 4MB Riser Card.
Number VRAM Slots		None.
L2 Cache Supported		IDT Cache in 256k, 512k, and 1MB densities.
DIMM Type		168-pin, 5v, buffered EDO, 2k refresh, 60ns.

As noted, the PowerBase-series have no VRAM slots on the logic board, and no on-board video circuitry, although this Mac's multimedia pedigree is intriguing, with a proprietary Power Computing 2MB or 4MB video riser card included with all shipping units. Unfortunately, with the demise of Power Computing, such video riser cards are virtually unobtainable at this time. Fortunately, this architecture also supports 7-inch PCI video cards, including accelerated third-party video cards. VRAM configurations and machine capabilities are hence only limited by third-party offerings.