1977-12-02 /BB-H138A-BM/01/3a-sources/usag20.ctl 1977-12-02 /AP-4172F-BM/01/3a-sources/usag20.ctl 1977-12-02 /bb-d868b-bm_tops20_v3a_2020_dist/01/3a-sources/usag20.ctl 1977-12-02 /bb-d868a-bm/01/3-sources/usag20.ctl 1979-12-04 /BB-4172G-BM/01/4-sources/usag20.ctl 1979-12-04 /BB-5255D-BM/01/4-sources/usag20.ctl 1979-12-04 /BB-D868C-BM/01/4-sources/usag20.ctl 1979-12-04 /BB-D868D-BM/01/4-sources/usag20.ctl 1979-12-04 /BB-H138B-BM/01/4-sources/usag20.ctl 1979-12-04 /BB-J713A-BM/01/4-sources/usag20.ctl 1979-12-04 /bb-d868c-bm_tops20_v4_2020_distr/01/4-sources/usag20.ctl 1982-02-04 /BB-M836A-BM/01/tools/usag20/usag20.ctl 1982-02-04 /bb-d868e-bm_tops20_v41_2020_dist_1of2/01/4-1-sources/usag20.ctl 1982-02-04 /BB-M836B-BM/01/tools/usag20/usag20.ctl 1982-02-04 /BB-4172H-BM/01/4-1-sources/usag20.ctl 1985-07-11 /BB-M836C-BM/01/tools/usag20/usag20.ctl 1987-11-19 /bb-m836d-bm/01/tools/usag20/usag20.ctl 1987-11-19 /tops20_version7_0_tools_tape_clock_tape/01/tools/usag20/usag20.ctl