David James Polewka <joseywales@outlaw.nospam> wrote:
+---------------
| rpw3@rpw3.org (Rob Warnock) wrote:
| >  code char
| >    0	Z	Stop [conditional on console switches & track addr]
| >    1	B	Bring [load]
| >    2	Y	Yank(?) [store AC<addr_field> ==> mem<addr_field>]
| >    3	R	Return address store [nextPC + 1 ==> mem<addr_field>]
| >
| >    4	I	Input [shift one 4-/6-bit char from KBD/tape into AC]
| >    5	D	Divide
| >    6	N	Multiply [saves lower half of result, usually an integer]
| >    7	M	Multiply [saves upper half of result, usually a fraction]
| >
| >    8	P	Print [shift one char out of AC to typewriter/tape]
| >    9	E	Extract [logical-AND memory to AC]
| >    f	U	Unconditional branch
| >    g	T	Test and branch if AC negative
| >
| >    j	H	Hold [store AC, leaving AC unchanged]
| >    k	C	Clear [store & clear accumulator (AC)]
| >    q	A	Add [memory to AC]
| >    w	S	Subtract
| >
| >Note: The LGP-30 used hex digits, but *not* the ASCII-based hex we all
| >know today, 0123456789abcdef, since it used Flexowriter code, not ASCII.
| >Instead, it used 0123456789fgjkqw. (Really.)
| 
| So, L, O, V and X were not used?
+---------------

Well, the Flexowriter code used by the LGP-30 was a bit weird, at least
to modern sensibilities. The Flexowriter was an "old-style" typewriter,
and like many typewriters of its day, didn't have a separate "1" key --
it used lowercase-L ("l") for that purpose instead. Also, with only a
6-bit code available, it used "stateful" shifts for alphabetic case,
as had been the case with Baudot telegraph code. That is, "l" & "L" 
read as, and were printed with, the *same* code, differing only by
whether there had been a preceding "shift-lock-upper" character sent
or not. And since normally input was done in 4-bit mode, all of "l",
"L", "B", and "b" read as the same thing, decimal 1. Likewise,
"@", "2", "Y" and "y" read as the same thing, decimal 2, and so on.

That said, to finally answer your question:

- "L" was used as the digit 1 (as above).

- The low-order 4 bits of V, O, & X duplicated the codes used by
  {<pi>,"7","M","m"}, {<sigma>",8","P","p"}, and {"(",9","E","e"},
  respectively, so while they were available for output, they had
  no particular defined input function.


-Rob

-----
Rob Warnock			<rpw3@rpw3.org>
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