PDP-10 RP attach/detach/boot issues

The pdp10_rp emulator had several problems:

1) disks are not recognized properly when they come on-line.  Same issue
as tapes, but not the same code paths.

2) The bootstrap code did not wait for disks to become ready.

3) The bootstrap code did not take the RH CSR address from the front end
(device).  Hence, would not boot if the device address was changed.

4) The bootstrap looked for the second HOM block at block 10 of the
disk.  Unfortunately, it read block 8.  10 is decimal; you need all 10
(decimal) fingers.

Fixes:
1) Implement spin-up delay.  A device that is attached/re-attached comes
on-line a second later.  Replace tests for 'attached' with tests for
up-to-speed.

2) Wait for the drive to become ready after issuing a controller clear.
When it's ready, write the attention summary register to prevent the
un-tended on-line interrupt for looking like an error.

3) Read the RHBASE from main memory instead of storing it there.  Teach
the bootstrap command to put it in memory from the dib, as it did with
the unit.

4) Read the correct block.

FILSER now gets on-line and off-line interrupts.
PDP-10 RP redux

The KS front end microcode actually reads the wrong alternate HOM block.
Teach the bootstrap to try the wrong one (in case someone counts on
this), but also the correct block.

Implement boot -A to emulate an autoboot - the boot that happens on
power-on or when the boot switch is pressed.  No questions, just boots.
Add -A to boot, Document & init FE comm area

The KS10's 8080 interfaces to the OS thru a small communications region.

The documentation is rather lacking, and the 8080 microcode is difficult
to follow.  Many years ago (while still at DEC), I worked it out, and
put definitions into TOPS-10.  They're now here, too.

Also, properly initialize the KLINIK communication words and the
keep-alive word.
PDP-10 tape boot rom update

The boot rom for tape didn't handle a tapes coming on-line, didn't take
the RH/TM/addresses from the FE.  The launcher also didn't handle
autoboot.

Now it does, with the restriction that ITS will only talk to UBA1.
PDP-10 tape boot rom update

The boot rom for tape didn't handle a tapes coming on-line, didn't take
the RH/TM/addresses from the FE.  The launcher also didn't handle
autoboot.

Now it does, with the restriction that ITS will only talk to UBA1.
Boot ROMs, again

Make the boot ROMs a bit easier to maintain.

Add assertion that the two variants of each are the same size.

Add offsets to the comments so it's easier to see where jumps are going.
Merge branch 'master' of https://github.com/tlhackque/simh
Merge remote-tracking branch 'origin/master'