Custom TTL design by Marvin Minsky. There are two displays: one
raster scan for bitmapped characters, and another random scan for
vector graphics. There is also a keyboard, and a UART for talking
to a host computer.
The computer is normally booted off a ROM which reads and starts a
secondary loader from the UART. The loader is responsible for reading
the payload, which comes in checksummed blocks. The LOAD command
accepts files in same format.
Both VT11 and VS60 properly autoconfigure on the PDP11.
PDP11 now runs Lunar Lander on all SDL supported platforms.
Reworked refresh logic to not require internal delays in the display library
