Ashley wrote:
>In the process of correcting myself, I noticed that System Profiler
>on my c500 reports:
>
>Total RAM: 32MB
> Logic board: 8MB DRAM
> DRAM 1: 8MB DIMM
> DRAM 2: 8MB DIMM
>
>The individual dimms are right, but the total is off by 8MB. (My
>PowerBase does have the correct total.) Tim, I no longer have an
>explanation for what's going on, but at least you're not the only one
>whose System Profiler can't add. ;)
That's right...Guru reports the C500 as having 16mb of onboard ram
http://www.everymac.com/systems/umax/c500/supermac_c500_180.html
confirms this.
it appears that although both Umax and PCC based their C500/PowerBase on the
Alchemy board, Umax chose the onboard w 2 slots while PCC went with 3 slots,
offering a slightly higher amount of ram overall. (144 v 160 max.)
Here's where it gets interesting...
GURU, Newer's ram upgrade utility gives DIFFERENT code numbers for the
ram used in the two machines (given the same amount of ram) and states that
the C500 needs 70ns ram v the PowerBase 60ns ram.
if we go back to an earlier note in this thread...
-snip-
>Also...from the http://www.macgurus.com website...
> Apple Technical Information Library (TIL) article Power Macintosh
>Computers:
>-snip-
> In the event FPM and EDO memory are mixed in these machines, the
>memory controller will address the DIMMs in Fast Paged Mode (FPM).
>Interestingly, MacGurus has noted far
> better compatibility in these Alchemy variants using 5v EDO rather
>than 5v FPM, and strongly recommends its use.
-snip-
it appears that EDO ram will be addressed as FPM ram when mixed.
ergo..EDO ram may or may not be 'seen' properly by system profiler and/or
may not be addressed properly by the memory controller of these machines in the
event that the two ram types are mixed.
Another issue here, which I've noted without quite understanding the 'why'
is that the memory controller will only address up to a 32mb dimm in the
first slot.
'why' would this restriction be built into the board??
Anyone??
Cheers...Michael
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