On Thursday (12/16/2010 at 08:28PM +0000), Tony Duell wrote:
 FWIW, I've just pulled a book off my bookshelf. 'Assembler Language
 Programmign, The IBM System/360 and 370', 2nd edition 1975.
 It says  :
 'Note that the letter O (Oh) is written as 0 to distinguish it clearly
 from the digit O (sero). We follow this convention in the description of
 any statement or card that is fed to the computer'
 So in that book (and presumably in other related manuals/documentation),
 the letter gets the slash. 
And I have a model 33 teletype here, with some provenance claiming an
IBM lineage, that has a slashed-oh between the I and the P keys and an
unslashed-zero next to the 9 key.
Pressing the slashed-oh, sends 0x4F and pressing the unslashed-zero
sends 0x30... and conversely, it prints an unslashed-zero when 0x30 is
sent to it and it prints a slashed-oh when 0x4F is sent to it...
--
Chris Elmquist