[TUHS] 211bsd: kernel panic after a 'here document' in tcsh
Walter F.J. Mueller
w.f.j.mueller at retro11.de
Mon Jun 26 02:25:25 AEST 2017
two remarks on the issues around FPSIM and tcsh:
I of course wondered by a line like
is accepted by 'as', I naively expected that this should cause an error.
I didn't locate the 211bsd 'as' manual, so checked 7th Edition manuals,
which can be found under
The assembler manual, see
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.
So the lexer sees two tokens
$4. --> number
. --> symbol for location counter
and, because the default operator is '+', interprets this as
mov $4. + . , r0
which ends up being a number in the 160000 to 177777 range.
So 'as' is not to blame, works as designed.
Noel Chippa wrote:
> I'm fairly amazed that apparently nobody has run across one of these 4 before!
> (Or, at least, not bothered to report it.)
> I wonder how long that bug has been in the code?
The answer is: this bug was in 211bsd all the time.
Steven Schultz told me that that they simply didn't have a way to
test FPSIM because all machines had FPP, and the only way of testing
would have been to physically remove the FP11 from a 11/70.
With best regards, Walter
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