The inhabitants of South Africa's biggest black township have taken a turn to consumerism, even attending a first-ever homemakers' exhibition here.

The novelty of the exhibition's carnival atmosphere in this drab living quarters of 1.2 million people outside Johannesburg, with its miles of substandard housing, is one of the things that is attracting them. People here say they cannot recall seeing candy-striped marquees or big hydrogen balloons in Soweto before.

An even greater novelty is the notion of home development, which the exhibition is promoting. Only in the past five years have urban blacks in South Africa been allowed to own their own homes. And it has been only two years since a $225 million scheme was launched to electrify Soweto, opening the prospect for black residents to own refrigerators, electric stoves and television sets.

Home ownership and electrification have been accompanied by residents' increasing financial resources that have allowed them to take advantage of the new opportunities. Laws restricting the kind of work that blacks could do and preventing them from joining labor unions have been changed, enabling them to advance into more skilled occupations and to earn better wages.

The result has been a rapid growth of black purchasing power and demand for consumer goods. Etienne Van Loggerenberg, an urban studies researcher at Johannesburg's Rand Afrikaans University, estimates that household incomes in Soweto have increased 50 percent in five years.

He said the township's total disposable income will soon overtake that of Johannesburg's affluent whites, whom the blacks outnumber two-to-one.

This shift has prompted the homemakers' exhibition. It is the beginning of a scramble for an emerging black consumer giant, in which a hopeful band of black businessmen are trying to claim priority ahead of their white competitors.

Veli Kraai, chairman of the Soweto Chamber of Commerce, which organized the exhibition, said during the opening that it was organized to encourage blacks to use their new purchasing power in the township rather than shopping at the white-owned stores of downtown Johannesburg.

In a neat reversal of apartheid, Kraai refused exhibition space to eager white retail chains, although he allowed white industrialists to show their merchandise.

These are the signs of changing times in South Africa since Pieter W. Botha became prime minister in 1978 and began cautiously reforming the policy of strict racial segregation, called apartheid, which his ruling National Party had been applying for 30 years.

There is disagreement about the ultimate purpose of Botha's reforms, but even his critics agree that a primary aim is to give more material benefits to a limited number of Africans permitted to live in the cities and to allow them more of a stake in the free-enterprise economy.

The cities are regarded as "white" in terms of the apartheid ideology, even though the labor force is black. Blacks working there used to be classed as "temporary sojourners" who were expected to leave eventually for tribal "homelands" in remote rural areas as separation evolved. That is why they were not permitted to own homes or run proper businesses in townships like Soweto, which themselves were regarded as temporary dormitories that would wither away as the urban blacks departed.

The only businesses that blacks were allowed to run were those like grocery stores, barber shops and coal dealerships that serve "the daily necessities of life." Anything more permanent was forbidden.

Now Botha has permitted home ownership, although still not under freehold title to the land but under 99-year leases. He has allowed blacks to form companies and even has established a Small Business Development Corp. to help them. Soweto now has three banks, two large supermarkets and 906 small businesses, according to a recent count by Van Loggerenberg.

Botha has ordered a crash program to reduce a massive black housing backlog and scrapped a law that prevented private contractors from helping with this.

Relaxing job restrictions on blacks and allowing them to join labor unions is part of the same policy turnaround by Botha. His statements on the subject indicate that he decided black job advancement would strengthen the economy.

Twelve years ago the government raised a storm when a central Johannesburg bank put a black teller in its front office for the first time. Labor Minister Marais Viljoen, now the figurehead state president, declared that such "shoulder to shoulder" integration was intolerable, and the bank had to move the teller to another cubicle. Today there are as many black tellers as white.

At the same time, the number of raids to arrest those who have come to the cities illegally has increased since Botha took over, and so has the number of enforced removals to resettlement camps in the "homelands."

Political analysts favorable to Botha claim he has to reform gradually because of his own and his party's past commitment to apartheid, and that these are only the first steps in an ongoing process.

Those more critical of Botha believe he is following a plan rigorously to limit the size of the urban black population to the minimum needed to run the economy, turning part of it into a skilled and stable middle class while thrusting the rest out of sight.