Fix time_t complaint when struct timespec doesn't have a time_t seconds value
PDP10 Update

Optimize DMA transfers to/from memory:
o Avoid shifting by zero
o Transfer complete (and aligned) PDP10 words whenever possible
o Precompute constant masks
o Explicitly hoist common subexpressions (for lazy compilers)

Document Unibus/PDP10 memory mapping

STOP if an unaligned word DMA is attempted.
SCP divots and enhanced help prototype

find_unit could return uptr undefined if find_dev returns the device disabled.
This upsets help routines that expect either a valid uptr or NULL.  Initialize the pointers to NULL.
And, have find_dev return NULL in the uptr as well as returning a NULL dptr.

Picky compiler casts.

Prototype for enhanced help.
Merge branch 'master' of http://github.com/tlhackque/simh
Merge branch 'master' into KDP
PDP10 Doc

Update TOC.  Add STOP codes
DUP: Temporary change

This allows the current KMC to function.  The real issues still need to be resolved.
KMC: New baselevel

Not quite ready for production, but useful.

This baselevel is another major update.  TX and RX are now threaded.
Debug and trace have been reworked.
Many, many internal changes.

This version runs (with a hacked DUP) TOPS10, TOPS20 & RSX.

The DUP issues need to be resolved.

There are unexplained performance divots.

This version also contains an exerciser for the prototype enhanced help system.