Five years ago a police bullet ripped into the throat of Hector Petersen, killing the 13-year-old student as his classmates looked on in horror. His death turned a protest march by black teenagers against the use of the Afrikaans language in their schools into an ugly riot.

The unrest and violence that followed for over a year in South Africa, with its overtones of racial civil war and a death toll of over 700, was an unprecedented, traumatic and frightening experience for white and black alike. The phrases "before '76" and "since '76" shoot up now like signal flags in every conversation about this country, as if the events of that year are an historic coordinate for it.

The events of 1976 were a vital turning point for South Africa, but apparently not a definitive one. Because while much has changed in the intervening years, much is also the same. South Africa remains "a house divided against itself" in which ruler and ruled continue to have totally different experiences.

For blacks, the past five years have brought material improvements in their lives, some of them significant. But there has been little change in the overall system which denies them any meaningful political power, which regulates almost every facet of their lives and in some aspects has become more repressive.

In contrast, the experience of the past five years for the Afrikaners, the 2.8 million whites of Dutch descent who dominate the government, has been both novel and disconcerting making them feel much has changed. Ironically, as they have seen their country become stronger militarily and economically and its vulnerability to outside pressures decline, they have also experienced a reduced sense of internal security and a disturbing loss of innocence.

The turmoil of 1976 forced the Afrikaners into the soul-searching consideration of how many blacks they would have to kill to restore order and maintain their political domination over a black majority of almost 20 million. And in a poignant way, the black students' rejection of the Afrikaans language held up to Afrikaners, as in a flash-back, their own historical struggle against the forced use of English in their schools a century ago.

Black nationalism became a reality to them. And they could sense, with their intimate understanding of a people's thirst for freedom and independence, then if their own struggle to gain political power, which was propelled by the same force of nationalism, was to be a precedent, then the future for them in South Africa is, at the least, uncertain.

In addition, research bodies funded by the Afrikaners' own government began producing reports confirming what apartheid's critics had been saying for years -- that the homeland system is an econmic flop and unworkable.

And hardly a day goes by now without an article in either the English or Afrikaans press about the expanding importance of skilled black workers if South Africa's economy is to grow and about the different birth rates that will reduce whites to an even smaller percentage of the population by the turn of the century than the 16 percent they now account for.

All of this has not shaken the conviction of the generation of Afrikaners now in power of their indispensability to South Africa. But the inescapable truth is dawning on their consciousness that they cannot hold on indefinitely, that the South Africa of today is unendurable, that the cultural and political isolation that was the Holy Grail of old-style apartheid is both lonely and dangerous and the cause of animosity against them.

"The whites cannot continue to decide and to rule alone, and the whites have realized this," comments the Afrikaans language paper Beeld, which has close ties to the government. "We are sitting on a time bomb which could blow the republic apart over the next 10 years if a political recipe cannot be found which will satisfy everyone," it says on another day.

Having admitted these truths, however, the Afrikaner has no clear vision of the future to replace the failed past. Plagued by division in his own ranks, he bumbles along, groping for solutions, vacillating between the attitudes and bad habits of the past and the tentative innovations which his pragmatism tells him are necessary.

So, for example, the government authorizes black trade unions but detains activist labor leaders. (There are over 30 in detention without trial now.) It acknowledges the homelands will never be economically viable on their own, but forces them to accept the charade of "independence." It seeks to build "growth points" to provide jobs for blacks in the countryside, then contues to resettle thousands of families into remote areas where there are no jobs. It admits the state cannot build enough houses for blacks in the cities, yet refuses to allow them to squat in home-made shelters.

The Afrikaner's pragmatism has made him aware of the need for political allies if he is to hold on to power. So the 2.5 million coloreds (persons of mixed race) and 750,000 Indians will be soon offered a chance to elect representatives to a national parliament. But his pragmatism runs into a dead end when it comes to the political rights of the country's black majority, especially those in urban areas. Here, the Afrikaner simply has no answer.

Leaving that hardest problem to last, the government has turned to undoing decades of discrimination in the economic sphere. Hence, the recognition of black labor unions, the removal of job reservations, the concern for training blacks and the building of a "constellation" of economic regions in which black and white will cooperate jointly.

The plan is to later graft a new political confederation onto this economic base, government planners say. But right across the political and racial spectrum there are skeptics who say that trying to separate economic apartheid from political apartheid will be less successful than trying to split a hair with crowbar.

But perhaps most dangerous for the Afrikaner who wants the world to believe in his good intentions is the government's growing authoritarianism which tends to nullify the reforms it makes. As if fearing the very changes it knows must come, it refuses to deal with any black or colored leader not of its own choosing or to allow change on any terms, at any pace and at any initiative but its own.

As good a place as any to see how these contradictions feel to those on the receiving end is in Soweto, the township one white official once called "the mirror of South Africa's soul." Since 1976 the government has accepted what was obvious to the 1.5 million Sowetans for decades -- that they are not going to return to some distant rural homeland and that Soweto is as much a permanent community as its sister city, Johannesburg.

Before 1976 blacks could not own the 103,000 homes they rented in Soweto nor the land beneath them. There were 15,000 people on the official waiting list for a home to rent. Today a black can get a 99-year lease on his home -- if he can raise the down payment and if he can find a home. Not one house has been built in Soweto since 1976, according to officials who administer the township. There are now 35,000 people waiting for a house, they say.

The bureaucratic foot-dragging in providing new houses has infuriated even Soweto's white officials, one of whom recently publicly threatened to resign unless the government did something about the problem.

In 1976 only 25 percent of Soweto's homes had electricity. By 1984 an ongoing $255 million electrification program will bring lights to all of Soweto.

Hector Petersen and his classmates were protesting against the forced use of Afrikaans in their lessons. They won that point. The use of Afrikaans is now voluntary. Other improvements have been made in the education system which serves almost 200,000 pupils in Soweto. There are 20 new schools, 562 additional classrooms since '76; black teachers' salaries have risen substantially and compulsory education is being phased in.

But the students' demand for one national education system in which the same amount of money is spent on black and white children has fallen of deaf ears. The school systems are still separate and unequal. The government spends more than $1,000 a year on the education of each white child and less than $100 a year on each black child a government minister boasted during the recent election.

Near Soweto's giant Baragwanath Hospital is a hugh warehouse-like structure, a symbol of the removal of restrictions on black businessmen in urban areas. "Blackchain," opened just last year, is Soweto's first mainly black-owned supermarket. It is, in fact, Soweto's first supermarket, period. The government is also setting up a small business administration to give loans to small black businesses and the first three of 40 industrial sites for black businesses are under construction in Soweto.

Black workers are using their new trade union rights to win concessions from employers; black civil servants are getting higher salaries and sports-loving Sowetans can now join white clubs if they wish. The government has announced it will soon repeal the last legal impediment to integrated sports clubs.

But all these improvements lose their shine when the larger picture is considered. Soweto remains a fortress without walls because of the migratory labor and influx control system that separates families and denies rural blacks free access to urban areas. And residents of Soweto are not free to change jobs and move to another city without permission of the local authirities.

Though the government has promised to "improve" the so-called pass laws, it has in practice done the opposite. The Black Sash, a voluntary group of white women helping blacks who run afoul of the pass laws, reported last January that the number of people coming to them for aid but for whom they would do nothing rose from 2,811 in 1978 to 7,582 in 1980. One-third of South Africa's prison population is pass law offenders.

Habeus corpus remains an alien concept to Soweto, where predawn police raids to capture suspected "terrorists" or drag black activits from their homes to months of solitary confinement are still common practice. In the past five years Soweto has lost the best and brightest in a generation of black political leadership through bannings, forced exiles and jailings while men elected with only a 6 percent turnout at the polls run the township's community council. Two Soweto newspapers and several of their reporters have been silenced by the government since 1978.

Police stations and government offices are surrounded by high barbed wire fences and the main roads leading out of the township are regularly straddled by roadblocks as police scrutinize the papers and cars of blacks in search of guns and "terrorists."

And yet the grenades are thrown and bombs laid on the railway lines, put there by young blacks whose significance lies less in the feeble impact of their violent activities than in the fact that practically every Sowetan shares their goal -- the right to be a citizen with the same political rights as whites in a national government representing all of South Africa, not some tribal reserve called a homeland. In short, an end to the divided house.