From mboxrd@z Thu Jan 1 00:00:00 1970 From: beebe@math.utah.edu (Nelson H. F. Beebe) Date: Tue, 17 Jan 2017 08:14:51 -0700 Subject: [TUHS] PDP-11, Unix, octal? In-Reply-To: <587e2a1e.bls9D6AZ7WMsQuDc%schily@schily.net> Message-ID: Joerg Schilling asks today: >> this has been done with 10 6 bit chars in a 60 bit word. >> Did people use octal in this area? I worked on a CDC 6400 with both NOS and KRONOS operating systems in the 1970s. The 6400/6600/7600 family were definitely in the octal world. Initially, the character set was 6-bit, with one character reserved as an escape to mean that the next 6-bit chunk was to be included, giving a 12-bit representation that added support for lowercase letters (a feature that we could only get on our IBM 360 and Amdahl 470 mainframes with a once-a-night change of the line printer glyph chain). Here is a quote by the lead architect, James E. Thornton, who wrote the 1970 book, ``Design of a Computer: the Control Data 6600'', and the 1980 history paper ``The CDC 6600 Project'' (http://dx.doi.org/10.1109/MAHC.1980.10044): >> The selection of 60-bit word length came after a lengthy >> investigation into the possibility of 64 bits. Without going >> into it in depth, our octal background got the upper hand. That comes from page 347 of the paper. ------------------------------------------------------------------------------- - Nelson H. F. Beebe Tel: +1 801 581 5254 - - University of Utah FAX: +1 801 581 4148 - - Department of Mathematics, 110 LCB Internet e-mail: beebe at math.utah.edu - - 155 S 1400 E RM 233 beebe at acm.org beebe at computer.org - - Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ - -------------------------------------------------------------------------------