> -----Original Message----- > From: IBM Mainframe Discussion List > [mailto:[EMAIL PROTECTED] On Behalf Of Bo Xie > Sent: Tuesday, July 05, 2005 10:54 PM > To: [email protected] > Subject: Does z/OS 24 bit,31 bit or 64 bit addressing mode > affect "1 byte is 8 bits"? > > > Hi, > > UNIX98 standard ed utility > "http://www.opengroup.org/onlinepubs/7990989799/xcu/ed.html"; shows: > --------- > If the size of a byte on the system is greater than nine bits, the > format used for non-printable characters is implementation-dependent. > --------- > I want to know whether 1 byte is still 8 bits in zOS 64 bit mode? > or int is still 32 bits in zOS 64 bit mode? Thank you! > > BTW. What system is "1 byte is greater than 9 bits"? for example? > > Best Regards, > Xie Bo >
<historical mode="on", pedantic="off"> Anymore, a byte is always 8 bits in length. I am not aware of any "main stream" processor for which this is not true at present. Also, in today's environment, an "int" is usually 32 bits (4 bytes). However, there were some systems in the past in which an "int" was 36 bits. As you can see if you do the math, that 36 is not evenly divisible by 8 (36/8==4.5). On these systems, a byte was usually 9 bits in length. In this context, a "byte" is not "8 bits", but rather "the fundamental unit of memory addressing" (or some such thing). If you do any C programming (or UNIX work), you will likely notice that octal is used quite a bit instead of hexadecimal. The reason, IIRC, is that the PDP systems upon which C and UNIX were originally developed were 36 bit machines. A 9 bit "byte" could be displayed as 3 octal digits. But could not be displayed at all using hex. <note - if this is incorrect, please forgive me, it's been too long> </historical> If you deal with telecommunications, you will notice that they always talk about an "octet". An octet has a definate defination of 8 bits. That's why they use it instead of "byte". No confusion. -- John McKown Senior Systems Programmer UICI Insurance Center Information Technology This message (including any attachments) contains confidential information intended for a specific individual and purpose, and its' content is protected by law. If you are not the intended recipient, you should delete this message and are hereby notified that any disclosure, copying, or distribution of this transmission, or taking any action based on it, is strictly prohibited. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
