No. On PDP 11 assembler the left and right shifts were a single < and >. You made a typo when transcribing the source statement: you typed but the actual code from m40.s reads However, since < and > where also used to delimit strings, there was a need to escape them so as to distinguish their usage as shifts from the string delimiters. The escaping was achieved by \ which is what you see in the code. See the assembler section of vol 2b of the Unix V7 manuals for details at http://plan9.bell-labs.com/7thEdMan/v7vol2b.pdf or http://web.cuzuco.com/%7Ecuzuco/v7/v7vol2b.pdf namely: 6.1 Expression operators The operators are: (blank) when there is no operand between operands, the effect is exactly the same as if a ''+'' had appeared. + addition – subtraction * multiplication \/ division (note that plain '' / '' starts a comment) & bitwise and | bitwise or \> logical right shift \< logical left shift ... ... ... j On Mon, 2 Oct 2006 09:44:58 +0300 jigsaw &lt;jigsaw(a)gmail.com&gt; wrote: Lion's book. > > But before I went far I was stopped by m40.s > > > What does the slash "/" stand for? > > I guess this line should be > > mov $USIZE-1<<8|6, (r1)+ > > Is "/<" the same as "<<"? > > I checked in Unix PDP11 Assemble Refrence Manual but didn't find a clue. ______________________________________________ LLama Gratis a cualquier PC del Mundo. Llamadas a fijos y móviles desde 1 céntimo por minuto. http://es.voice.yahoo.com