From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 10f6aa,76b1fcc14e8dced X-Google-Attributes: gid10f6aa,public X-Google-Thread: 103376,c9c309a1859318a1 X-Google-Attributes: gid103376,public X-Google-Thread: 1014db,8b6c45fbebd7d3b7 X-Google-Attributes: gid1014db,public X-Google-Thread: 114917,76b1fcc14e8dced X-Google-Attributes: gid114917,public X-Google-Thread: 109fba,76b1fcc14e8dced X-Google-Attributes: gid109fba,public From: miker3@ix.netcom.com (Mike Rubenstein) Subject: Re: HELP ! need to insert value in array !! Date: 1997/07/04 Message-ID: <33be891f.47731103@nntp.ix.netcom.com>#1/1 X-Deja-AN: 254658056 References: <33A9C27C.22F7@post4.tele.dk> <5oci49$97g@crl.crl.com> <866920621snz@genesis.demon.co.uk> <5p0v7l$9uc@nntp.seflin.org> <33b64c2f.43589878@nntp.ix.netcom.com> <5pht85$d4o$1@goanna.cs.rmit.edu.au> Organization: Netcom X-NETCOM-Date: Fri Jul 04 4:53:19 PM PDT 1997 Newsgroups: comp.lang.c,comp.lang.c++,comp.os.msdos.programmer,comp.lang.asm.x86,comp.lang.ada Date: 1997-07-04T16:53:19-07:00 List-Id: dewar@merv.cs.nyu.edu (Robert Dewar) wrote: > iRichard O'Keefe said > > < > I think that is wrong, there were hardware instructions on the PDP10 that > used this format, I am pretty sure of this, but it is a while ago ... > Not really, at least not in the sense that there were instructions that handled 7 bit characters specially. The PDP10 (like its predecessor the PDP6) had a byte pointer construction that could be used to access any byte in a word where the byte size was specified as part of byte pointer. There was an instruction that would get a byte and increment the pointer, handling word boundaries properly (a byte could not be split across words). Byte pointers and the associated instructions worked equally well with any byte size up to 36 bits, though, of course, some word sizes resulted in more wasted bits than others. The reason for 7 bit characters was simple -- it was the smallest standard character size that provied both upper and lower cast. 9 bit characters would have wasted more memory in text applications of the time and standard peripherals couldn't handle more than 7 bit ASCII anyways. While the maximum memory on early models was 256K 36 bit words, early machines that large were rather rare on because of the high cost of memory. Michael M Rubenstein