Choppy has had a bit of experience translating hex and octal into
binary groupings.   The computer stores magnetic signals which
we usually interpret as binary digits, or bits.  Three taken together
can be interpreted as an octal number; six made a character in
the old days.  We called that, incorrectly, binary coded decimal,
or BCD  Octal was easy in the sense that the digits are 0-7.
Grab four at a time and you can interpret it as a hexadecimal digit.

I don't particularly like the word hexadecimal because it is a hybrid
name, hex from Greek and decimal from Latin.   Greek didn't do
16 as a simple compound word, but as a phrase, like the French
twenty and one for 21.   Latin liked compounds of our sort, but the
word for six is sex, so sexadecimal would be proper Latin, but maybe
offensive to tender spirits.  You can take a grouping of any size and
interpret it as binary.

Problem with some computers and their operating systems  is that
they store integer numbers in the standard way, with usually the sign
coded into the number in some complement form. These same
machines often handle what they think are strings of characters in
reverse order to the groups of bits regarded as numbers in each
character position.

Then there were machines in the bad old days that used other ways
to code numbers with bits, like the bi-quinary system of the IBM 650.

But eight bytes is 40 bits on a modern machine.   We didn't use the
word byte for octal characters, or for the 7 bit characters used by
mainframes to communicate with terminals.  Remember them?

It was wonderful in the old days figuring out what an address in an
error message meant.  VAX stood for Virtual Address eXtended,
or so DEC said.

Choppy

At 04:07 PM 6/19/02 -0500, you wrote:
>It appears to be 40 bits indeed.   I bet Choppy has had some experience
>translating hex and octal into 4 and 3 bit binary groupings?
>
>Anybody remember dealing with grey-code?


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