CD-ROM recovery software?

Nicholas Leippe nick at leippe.com
Thu Apr 9 10:17:25 MDT 2009


On Thu Apr 9 2009 10:00:56 Michael Torrie wrote:
> Nicholas Leippe wrote:
> > http://www.new-brunswick.net/workshop/c++/faq/intrinsic-types.html
> >
> > PDP-10 had 36-bit bytes.
>
> Are you sure you don't mean to say the PDP-10 had 36-bit _words_?  I
> think the reference to a 36-bit "byte" is an implementation detail of
> the C++ compiler on the PDP-10, not a definition of the hardware itself.
>  Of course since the PDP-10 could not address any chunk within that
> 36-bit word, the distinction is probably a bit pedantic.

The topic in the FAQ is the definition of a byte within the C/C++ language. 
Within that context a byte in C/C++ on a PDP-10 will have 36 bits.

Other languages may do differently of course. But the point is as you said, 
that the smallest addressable unit of memory on that architecture holds 36 
bits.

The definition of a machine word size can also vary. Usually that is defined 
by either the register size (how many bits the cpu can operate on at once), or 
the memory width (how many bits the cpu can transfer at once), or a 
combination of the two. The earlier Motorola 68k cpus were classified as 
16/32, because they had 32 bit registers but only a 16-bit wide memory bus. I 
believe the Intel 8088 was similar, being 8/16. But, a byte on both of those 
cpus held 8 bits.







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