PART OF THE APPEAL of John Carpenter's Halloween and Assault on Precinct 13 lies in their essential vileness, and in the harsh, sly, single-minded persistence with which Carpenter strums and strains his audience's nerves. Assault on Precinct 13 is a kind of hipped-up, relocated Western: an undermanned Los Angeles police precinct station is besieged by a silent army of murderous street gangsters; Halloween is a scare picture about an escaped lunatic who, having returned to his home town Halloween night, stalks some high school girls babysitting in adjoining houses. The combined budgets of these two films total a great deal less than half the production costs of the more solemnly ingratiating Academy Award nominees you are likely to see in their places. In each, against the pulpy, gritty texture of the surface plot, an arch and fastidious intelligence glistens and clings like some slime on a rock. These films are constructed with canny, modest movie-making acuity, and within what they try for and accomplish they are as powerfully successful and surprising as anything of their kind currently on view.

Assault on Precinct 13 and Halloween develop out of the simple, steady building up and then the furious release of pressure implicit in their plots. Carpenter wrote and directed both films, and composed his own music. He is especially skillful in constructing and sustaining situations that can cause an audience to yell, and, watching these films, there is the peculiar pleasure of being in a crowd that can't keep its mouth shut for excitement.

Of the two pictures. Assault on Precinct 13 is the most solidly worked out and the most satisfying. Ignored as an exploitation film upon its initial release in 1976, it is Carpenter's second feature (his first was a science-fiction spoof expanded from a film school project, called Dark Star.) The basic situation and central characters, actors' mannerisms and shards of dialogue are derived from Rio Bravo, a late Howard Hawks film. Assault largely inexperienced cast lurches beneath the preposterous weight of a self-consciously anachronistic script. The dialogue is as tersely as any Hawk's film, and it is often difficult to tell whether the actors mouthing it are sarcastic or inept. All the same, spry gusts of parody whip around the edges of certain lines and actions. There is for example, a disarmingly silly moment when two of the men trapped in the station, squabbling about who should risk an unlikely escape attempt, settle on a quick game on one-potato two-potato.

Halloween, while still cheaply made, is a much slicker, more flagrantly commercial movie than Assault, and it has been grossing big money. Carpenter employs a gliding subjective camera throughout, alternating between the killer's and the victims' points of view, producing a continual, stomach-tightening sense of menace. There is surprisingly little blood in the movie, scarcely any nudity, and, considering the story it comes out of, and the opportunities available for flat-out ghoulishness, Carpenter has produced a tame and tactful film. However, most of Assault's quirky humor and antic allusiveness have been rubbed away, and Halloween, by comparison, is thinned by the expenditure of so much energy towards pure scariness. Carpenter flirts, here as in Assault, with some vaguely metaphysical notions about fate and death and evil, but you get the sense that he isn't really serious about it, and is merely doodling in the exceptionally wide margins of his plots.

The discomfiting question remains: what makes these films so riveting, when we would have little interest or patience for the same stuff on paper or in the hands of a less talented director? It is largely Carpenter's gleeful knowingness, in constructing a situation and co-ordinating an action, with regard to what his audience expects or surmises from any given scene. He tugs at the nerves most sharply through sly scare-tactics: close calls, delays, false alarms, the expectation and possibility of violence as often as the brutal thing itself. He can make sudden action at once surprising and coherent, and, despite the relative poverty of his productions, the direction in each film is practically seamless. Nearly every scene appears to be the product of all the right decisions about where the camera should be and when it should move. Such ingenuity and control displays itself in ways that are embarrassing to name: the breathtaking efficiency, for instance, with which one character in Assault snaps a man's arm at the elbow; or the startling, gimmicky appearance, time and again, from out of nowhere, of the masked killer in Halloween, whose presence is signalled by an amplified breathing sound and a supernatural thrum. Carpenter's action sequences are especially resourcefully engineered. There is one virtuoso scene in Assault on Precinct 13, in which the station office room receives an intensive barrage from outside: the street gang is equipped with silencers stolen from a government arsenal, and the only sound, as we watch the room being ripped apart, is the quiet clicking and crumpling of glass and venetian blinds, concluding with a wittily timed puff of bullet-scattered papers off a disheveled desk.

Apart from the main shocks and spasms of violence, numerous small touches--a subtle darkening of light or deadening of sound--all carry their quiet effect and chill. Some of the best things in both films lie in the casual and exact use of particular locales. In Assault, the desolate quality of a faded section of Los Angeles is captured perfectly in the disconsolate look of a parking lot, a few haggard palm trees, and a grim, sloping street, and there is a similarly good, throwaway treatment of leafy suburban lawns in Halloween.

"If I had three wishes," Carpenter said in an interview last year for sight and Sound magazine, "one of them would be 'Send me back to the 40s and the studio system and let me direct movies."' Carpenter's cunning proficiency, the workman like spit and polish of his low budget productions and his obvious debt to and affection for earlier movie-makers have tempted a number of critics to consider him a clever contemporary heir to several 40s and 50s directors whose exciting grade-B films have been sauvely generalized under the label film noir. Just now, with the success of Halloween, more careful critics are insisting that Carpenter is not as good as all that.

THE DEFICIENCIES of Carpenter's films are easy to identify: too many of his scare effects start in the stomach rather than in the brain; his characters and the actors who play them have their purpose chiefly as puppets to be twitched along as the stories demand; he exhibits little knowledge of how people really talk and think, and the whole premise and intent behind each of his movies is as simple-minded and morally undernourished as the genres require. You would hope for a great deal more from his best movies--the best, even, of this limited, specialized kind--than Carpenter may be capable of, but Halloween and Assault on Precinct 13 are such neat packages of self-acknowledged hokum that it is difficult to resent or condescend to them. Compared to the slackness and swaggering middlebrow pretension of recent thrillers like The Invasion of the Body Snatchers or The Last wave, they are remarkable for their stringent suspensefulness, their fundamental lack of conceit, the inventiveness of numerous details and situations, and a sharp, reverberant visceral twang.

Carpenter's name, critics have been quick to point out, provides the best definition for his particular kind of talent: he is a first-rate carpenter, a makers of suspense shockers, scare pictures a good hack working an old saw. The wood may be warped and a little green, but he is not going very deeply against the grain. Whether he might rank among the architects of the traditions he so admires is an open question. Whether he can resist the beveling and varnish a big budget often imposes remains to be seen.