As SALT II is currently on display down on Pennsylvania Avenue, the hardware salesmen behind such things as "verification" and the "electronic battlefield" were holding their annual convention up the street at the Sheraton Park Hotel.

They were dressed in full battle regalia - for the young salesmen that meant a three-pece suit and a well manicured mustache, and for the young saleswomen it meant a conservative dress slit up past the knee - while they displayed wares from the instant sniper-detector to the Laser Communication Satellite System to the long-distance electronic blackboard.

The three-day convention, the 33rd annual for the Armed Forces Communications and Electronics Association, drew some 10,000 visitors and participants to see 454 exhibits that looked like the Fortune 500 list in three dimensions, complete with plush carpet, glass conference rooms, TV monitors and overstuffed chairs and coughes in the booths.

Represented were companies such as IBM, Rockwell International, Xerox, RCA, Generl Electric, and others who compete for businesses in a field they call C3I - communications, command control and intelligence.

Million-dollar pieces of equipment were scattered about the room amid elaborate models of satellites, space shuttles, rockets and handfuls of electronic chips that looked like elaborately carved jewelry.

At the bell Telephone exhibit, the new "electronic blackboard" was on display - it allows the user to chalk a diagram on a blackboard while it simultaneously appears on video screens in locations around the world, using ordinary telephone lines. Right now, it costs $500 a month to rent.

RCA was displaying a set of laser binoculars infantrymen can use to find the range of an enemy soldier or vehicle instanlty by pressing the laser button and getting a reading generated by the laser beam bouncing off the sighted object.

A red-bearded Scotsman described the virtues of a sniper-detector or "the hostile indicator," which is a set of three boxes that can be attached to military vehicles, cars, speakers' podiums, and can detect a fired bullet and instantly designate the direction from which it came.

The detector, made by Microwave and Electronic Systems, Ltd., sets off an alarm and indicates the direction of the sniper half a second before the sound of the gunfire reaches the vehicle, if the sniper is 300 feet away. It enables soldiers to react by ducking and quickly turning to fire directly at the sniper.

Up in the third-floor hotel room, D. J. Hume gave a little demonstration of the device by reclining on a couch and firing what looked like a .44 revolver (but which shot pellets) at a target on a speaker's podium in the room. An alarm sounded and a flashing arrow pointed in his direction. "You know," he said, "if one of these things had been installed on President Kennedy's car in Dallas, the instant that box went off the chauffeur could have slammed on the pedal and left have motorcade behind."

The device might have saved Kennedy, he said, and also would have settled the question of one or two gunmen and where they fired from, because the detector can keep track of two snipers at once.

AFCEA staffers, in looking over the several rooms full of exhiibits at this year's convention, said the whole electronics revolution over the past few decades could be seen in the the convention's changing exhibits. They recalled a convetion in 1956 at which the big items were new sets of earphones, great lumbering, clattering teletype machiines, and the many wiggling spikes of antennae.