As seen above, after nailing down the socket issue on my prototype Altair 680 RAM board, I wrote a little Cylon or Larson scanner program under Altair 680 BASIC, using the lamp register. Here's the code:

Code:
10 READ D
20 IF D = 0 THEN 70
30 POKE 61456, D
40 FOR C=0 TO 50
50 NEXT C
60 GOTO 10
70 RESTORE
80 GOTO 10
100 DATA 128, 64, 32, 16, 8, 4, 2, 1
110 DATA 2, 4, 8, 16, 32, 64, 0
The DATA statements hold the bit pattern for the lamp register.