~F8CART DRIVING COMMANDS________________________________________________

  F      Drive forwards.
  B      Drive backwards.
  L      Turn wheels hard left.
  R      Turn wheels hard right.
  αL     Pan camera left.
  αR     Pan camera right.
  SPACE  Stop the cart.
  RETURN Exit cart command mode.

	First, and  most important is  understanding how to  stop the
cart.   The teletype halt command is  SPACE; also any character other
than "F", "B",  "L",  or "R" will stop  the cart.  Cart commands  are
passed first from  a teletype to the PDP-10; then  to the PDP-6; then
over  a citizens  band,  27.045  megahertz,   radio link  to the cart
control logic. When communication is lacking between  entities in the
chain of  command the lower entity  times out and causes  the cart to
halt. The cart control logic times out  in a fifth of a second if  it
does not  hear from the  PDP-6; the  PDP-6 times out  in less than  a
minute  if  it  has  not  heard  from  the  PDP-10; the  PDP-6  stops
broadcasting cart commands  if it  detects the death  of the  PDP-10;
the PDP-10  job times  out after  5 minutes of  not hearing  from the
teletype and kills the PDP-6 spacewar job.

	Second,   and of occasional interest  is understanding how to
make the cart go.   The command "F"  will make the cart  go forwards;
and the other  commands will cause action as  mentioned in the table.
If the cart fails to move; all its switchs should be check for  being
in the  ON or  AUTOMATIC or FAST  position; all  its plugs should  be
plugged  in; and  its  batteries should  be checked.    Recently cart
failure had been most  often caused by  the radio transmitter in  the
Kludge Bay.  Check to see that  the transmitter is turned on and that
the  PDP-6 is running.  Hitting and  shaking the transmitter; as well
as disconnecting  and reconnecting  its power; will  usually make  it
work.

CART HARDWARE DIAGONOSTIC____________________________________________

  V          Enter diagonostic listen loop.
  RETURN     Exit diagonostic listen loop.

  NUMERALS:   0,1,2,3,4,5,6,7  send direction relay bits.
  CHARACTERS: H,A,B,C,D,E,F,G  send action relay bits.

	The cart diagonostic  listen loop simply takes the  low order
four  bits of  a non-carriage return  ASCII character  and broadcasts
them to the cart. The cart decodes four bit radio command  bytes into
six  relays; commands  0  thru  7 set  the  pan,  drive, or  steering
direction  relay repective to bits 4, 2 and  1; commands A thru G set
the pan, drive,  or steering action relays  respective to bits 4,  2,
and 1.
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~I1973,800;F8- 38 -