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Re: PDP-11 compat mode [was Re: New Vax - future directions :-)]

>>              C <- {borrow into most significant bit};

>> That looks...implausible.  I believe it should be

>>              C <- {borrow out of most significant bit};

> You're correct; the description you cited is an obvious typo.

A nigh-ubiquitous one!  Turns out EL-00032-00-decStd32_Jan90.txt
contains much the same language in other places as well.  Here are the
ones I've managed to find:

- The description of the C bit of the PSL (page 1-27),
- The description of DEC{B,W,L} (page 3-17),
- The description of SBWC (page 3-30),
- The description of SUB{B,W,L}{2,3} (page 3-31),
- The description of compatibility mode SBC{,B} (page 9-20),
- The description of compatibility mode SUB{,B} (page 9-28), and
- The description of compatibility mode CMP{,B} (page 9-29).

I think this may be every case of subtraction affecting a C bit; I
can't think of any others offhand.

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