performance with >> 9 MW of memory

[Chucko@CHARON.arc.nasa.gov (Charles R. Fry)]

    Date: Mon, 9 Dec 1991 08:56 PST
    From: p2@porter.asl.dialnet.symbolics.com (Peter Paine)

    I see on the MacIvory II Show Machine Configuration:

    NuBus slot C: National Semiconductor NS8/16 Memory Expansion Card p/n
      NS8/16 (id #x10F) rev Rev. 2.21, 16MB total, 2.6MW in use

    (* 2.6 40/8) = 13 Mbytes - where did the other 3 Mbytes go?

The Ivory chips have memory error correction logic on-chip.  So while
the word width is 32 bits pointer/data + 8 bits tag = 40 bits, the
memory bus has an additional 8 bits for 48 bits memory word length.
Thus 16 MB / (48/8) = 2.6 MW, more or less.