C SUBROUTINE OS8BLK (V1A) - CALCULATES ABSOLUTE TRACK AND SECTOR ADDRESSES C OF A GIVEN OS/8 BLOCK NUMBER C SUBROUTINE OS8BLK(BLOCK,SECTOR,TK1,TK2) INTEGER*2 TK1,TK2,SECPTR,BLOCK,SECTOR(4) BYTE INTL(28) C C INTERLEAVE TABLE - 2:1 SECTOR INTERLEAVE FOR OS/8 C DATA INTL/1,3,5,7,9,11,13,15,17,19,21,23,25, 12,4,6,8,10,12,14,16,18,20,22,24,26,1,3/ C C LOAD SECTOR ARRAY FROM INTERLEAVE TABLE C SECPTR=MOD(BLOCK*4+1,26)-1 DO 10 N=1,4 10 SECTOR(N)=INTL(SECPTR+N) C C LOAD TRACK ARRAY C TK1=BLOCK*2/13+1 TK2=TK1 IF(SECPTR.EQ.24)TK2=TK2+1 RETURN END