QSIC update - v6 Unix boots and runs

[David Bridgham]

> FWIW, so does RT11, and in the case of writes, it requires the rest of the block to be zero-filled.  Not everything depends on this, but some parts do; I think Fortran is one.

I did implement that too.  Unix doesn't need it but I had to fill the
block with something and it wasn't that hard to zero out the value.  I
figured something would come along that required it.  There is still a
whole lot of the RK11 functionality I need to implement, much having to
do with handling and properly reporting error conditions.  It's still
pretty cool to boot up Unix and type commands at it.  Doubly cool to
watch the indicator panel blink away while I run programs.

By the way, that indicator panel has been ridiculously valuable for
debugging this thing.  I did it initially just because I thought it
would be fun and I needed to take a break from some frustrating bug but
it's turned out to be far easier to use than the logic analyzer (which
I've never hooked up).  I just generate a custom FPGA load that displays
some register I think will tell me what's going on or even sometimes
create additional counters with specific triggers that can monitor the
internals of my implementation.