The costs of the i386 to x86-64 upgrade
If you read my previous article on DOS memory models, you may have dismissed everything I wrote as “legacy cruft from the 1990s that nobody cares about any longer”. After all, computers have evolved from sporting 8-bit processors to 64-bit processors and, on the way, the amount of memory that these computers can leverage has grown orders of magnitude: the 8086, a 16-bit machine with a 20-bit address space, could only use 1MB of memory while today’s 64-bit machines can theoretically access 16EB. All of this growth has been in service of ever-growing programs. But… even if programs are now more sophisticated than they were before, do they all really require access to a 64-bit address space? Has the growth from 8 to 64 bits been a net positive in performance terms? Let’s try to answer those questions to find some very surprising answers. But first, some theory.
October 7, 2024
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Tags:
blogsystem5, hardware, unix
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18 minutes)
Recovering two old Macs
Wow, it has already been three years since a friend an I found a couple of old Macintoshes in a trash container1. Each of us picked one, and maybe a year ago or so I gave mine to him as I had no space at home to keep it. Given that he did not use them and that I enjoy playing with old hardware, I exchanged those two machines by an old Pentium 3 I had laying around :-) The plan is to install NetBSD-current on at least one of them and some other system (or NetBSD version) in the other one to let me ensure ATF is really portable to bizarre hardware (running sane systems, though).
July 16, 2007
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Tags:
atf, hardware, mac
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3 minutes)
Hard disks and S.M.A.R.T.
Old hard disks exposed a lot of their internals to the operating system: in order to request a data block from the drive, the system had to specify the exact cylinder, head and sector (CHS) where it was located (as happens with floppy disks). This structure became unsustainable as drives got larger (due to some limits in the BIOS calls) and more intelligent. Current hard disks are little (and complex) specific-purpose machines that work in LBA mode (not CHS).
December 4, 2006
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Tags:
hardware, smart
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3 minutes)
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