ABC's televised dramatization of "Roots" set almost every all-time television rating record and enabled ABC to dominate last week's top program rankings as no network has ever before, according to A. C. Nielsen Co. figures released yesterday.

Sunday night's two-hour conclusion to the eight-part, 12-hour television version of Alex Haley's novel of Afro-American history, attracted 80 million viewers - the largest single-program TV audience in the 27 years such records have been kept.

The seven preceding episodes of "Roots" captured the top seven spots over 60 other prime-time television programs last week, and, together with Sunday's conclusion, captured eight of the top 13 spots on the all-time TV program popularity list.

That list of all-time popularity leaders is now topped by Sunday night's episode of "Roots," followed in second and third places by the previous all-time leaders, parts one and two of "Gone With the Wind," which were tlecast by NBC last November.

The "Roots" episodes of Jan. 28, 27 and 25 have take over fourth through sixth places on the all-time list, with last month's Super Bowl XI in seventh place and the "Roots" episodes of Jan. 24, 26 and 29 filling out the top 10. The "Roots" episode of Jan. 23 ranks 13th on the all-time list, following two other Super Bowl football games.

"Roots" also was so powerful in attracting viewers to other ABC programs that the network's shows captured the top 16 places in last week's Nielsen ratings, breaking the old CBS record of sweeping the top 15 places.

In fact, all 21 of ABC's prime-time (8 to 11 p.m.) shows last week finished among the top 26 Nielsen-ranked programs. A record average of 25 million American TV households tuned in to ABC every day last week, according to Nielsen, giving the network a startling 52.1 per cent of all television sets tuned in between 8 and 11 p.m.

The overwhelming ABC superiority for the week enabled CBS, with an average of only 11 million TV households tuning in, finally to catch up with NBC and tie it for second place over-all for this television season. NBC averaged a "mere" 9.3 million TV homes last week, the 19th of the season, in the face of the "Roots" competition.

CBS highest ranked show last week was 17th-place "All in the Family," which can usually be counted among the weekly top 10. NBC's top-ranked show was "Little House on the Prairie," which came in 24th, about 10 places below its usual rank.

ABC's one-week ratings sweep has apparently put the new number-one ranking network out of reach of its rivals for the 1976-77, TV season crown.

Since September, ABC has averaged 21.9 Nielsen points overall to 18.7 for CBS and NBC, which means a lead of approximately 2.2 million TV homes every night of the season for ABC over the other two networks.