impressive
ALGOL
COBOL
CRT spot
DM display
Doppler signal
EDP
FORTRAN
IF signal
IM display
RF echoes
Roman candle
Teletype
Wirephoto
aid to navigation
alarm
alert
alphabetic data
alphanumeric code
amber light
angular data
announce
arresting
assembler
astonishing
badge
balefire
banner
beacon
beacon fire
beam
beat signal
beat the drum
beckon
bell
bell buoy
binary digit
binary scale
binary system
bit
blink
blinker
blips
blue peter
bounces
broad hint
broadcast
bug
buoy
byte
caution light
signalled
signalling
incitation
incitement
provocation
signaled
signaling
signally
signals
signature
channel
circuit
command
control
data
device
frequency
input
message
pattern
response
source
noise