Slashed letter O, unslashed letter zero

[Paul Koning]

> On Apr 26, 2022, at 4:41 PM, ben via cctalk <cctalk at classiccmp.org> wrote:
> 
> ...
> PS: Did any common I/O devices have the ALGOL symbols Less than or Equals, Greater than or equals , not , arrows and other misc symbols?

Yes, the Flexowriters at TU Eindhoven used to punch ALGOL programs for the Electrologica X8 machine there (late 1960s through early 1970s).  As I recall, Dijkstra made some comment somewhere about the usefulness of being able to specify your own character set.  

Those machines had upper/lower case letters, several special character such as the logic symbols not, or, and, the subscript 10 for exponential notation numbers, plus non-escaping underline and vertical bar.  The underline was used for keywords, so the ALGOL keyword "begin" was keyed as _b_e_g_i_n.  It would also make several other special characters, for example _= (underlined equal) is the Boolean equivalence operator, and _ followed by the not symbol gives you the "implies" operator, and _< is less-or-equal.  The vertical bar would also make several overstruck symbols, for example |= becomes not-equal, | followed by the and symbol is uparrow (for exponentiation).  The local inventions |< and |> were used for string quotes.

Here's a sample of what it would look like printed on the Flexowriter.  The line printers were upper-case only; they'd print lower case letters as upper case, upper case letters overprinted with a period.  Ugh...

	paul