1982-11-30 /BB-4172H-BM/01/4-1-sources/t20exa.rel 1982-11-30 /BB-M781B-SM/01/exec/t20exa.rel 1982-11-30 /bb-d868e-bm_tops20_v41_2020_dist_1of2/01/4-1-sources/t20exa.rel 1989-10-10 /BB-Y390S-BM_1990/01/t20src/t20exa.rel 1990-05-07 /BB-Y390T-BM/01/t20src/t20exa.rel 1990-05-07 /BB-Y390U-BM/01/t20src/t20exa.rel