15 Oct
2011
15 Oct
'11
7:58 p.m.
On 10/15/2011 8:39 PM, Eric Smith wrote:
ben wrote:
How ever this is under C triva, not the latest standard of the year.
So what does the C-bible say on this?
I don't know about C, but I assume that 7 bit
ascii is standard for
everybody
but IBM 360's.
The PDP-10's native character sets are 7-bit ASCII (originally the 1963
edition) packed five characters to a word, with a leftover bit, and
"SIXBIT" which is the 64-character printable subset (not including the
lower-case region), packed six character to a word (or sometimes three
characters to a half-word).
The C standard requires that the character data type fit in a byte
(ISO/IEC 9899:1999 sections 3.7.1 and 5.2.1), but byte is simply defined
as a unit of data storage large enoguh to hold any member of the basic
character set, so that is a tautology.
However, the standard also requires that the character type occupy at
least 8 bits, that the minimum range for unsigned char is 0 to 255, and
that the minimum range for signed char is -127 to +127 (section 5.2.4.2.1). This rules out the use of 6-bit and 7-bit characters,
so the native
PDP-10 text representation cannot be used as the C standard character
type at all.