RAM configuration tricks on A/UX?
Richard Michael Todd
rmtodd at uokmax.UUCP
Sun Jun 4 11:58:33 AEST 1989
In article <4105 at emory.mathcs.emory.edu> km at mathcs.emory.edu (Ken Mandelberg) writes:
>I wish there was a trick that let us just add a 1 meg simm to the 4
>already there. Every Unix kernel I have seen (prior to A/UX) has been
>very flexible on sizing memory. I don't know what the real issues are
>on the MacII, but at the very least MacOS will not boot with 5 1 meg
>simms, which gives no way to boot A/UX.
The reason you can't just stick in a single 1meg SIMM is due to the
hardware design of the machine, NOT the OS involved. The data bus is 32 bits
wide and the SIMMS are only 8 bits wide. The memory bank has to be able to
present a full 32-bit word to the CPU whenever the CPU accesses it. When you
plug in a single SIMM into the memory bank, the CPU tries to fetch 32-bit
words from memory and gets 8 bits of data and 24 bits of garbage. It just
won't work. That's the price you pay for having a real 32-bit processor in
your machine, instead of an 8088 :-).
--
Richard Todd rmtodd at chinet.chi.il.us or rmtodd at uokmax.ecn.uoknor.edu
aka ...!sun!texsun!uokmax!rmtodd
"MSDOS is a Neanderthal operating system" - Henry Spencer
More information about the Comp.unix.aux
mailing list