UNIX 6th Ed. - /usr/source/mdec/tm.s

   1: mts = 172520
   2: mtc = 172522
   3: mtbrc = 172524
   4: mtcma = 172526
   5: 
   6: tread:
   7: 1:
   8:         mov     ba,mtma
   9:         cmp     mtapa,tapa
  10:         beq     1f
  11:         bhi     2f
  12:         jsr     pc,rrec
  13:         br      1b
  14: 2:
  15:         jsr     pc,rew
  16:         br      1b
  17: 1:
  18:         mov     wc,r1
  19: 1:
  20:         jsr     pc,rrec
  21:         add     $256.,r1
  22:         bmi     1b
  23:         rts     pc
  24: 
  25: rrec:
  26:         mov     $mts,r0
  27:         bit     $2,(r0)+                / rewind status
  28:         bne     rrec
  29:         tstb    (r0)+           / cu ready
  30:         bpl     rrec
  31:         inc     r0
  32:         mov     $-512.,(r0)+    / byte count
  33:         mov     mtma,(r0)       / bus address
  34:         mov     $mtc,r0
  35:         mov     $60003,(r0)             / read 800bpi
  36: 1:
  37:         tstb    (r0)
  38:         bpl     1b
  39:         tst     (r0)+
  40:         bpl     1f
  41:         mov     $-1,(r0)
  42:         mov     $60013,-(r0)            / backspace
  43:         br      rrec
  44: 1:
  45:         add     $512.,mtma
  46:         inc     mtapa
  47:         rts     pc
  48: 
  49: rew:
  50:         mov     $60017,*$mtc
  51:         clr     mtapa
  52:         rts     pc
  53: 
  54: mtapa:  0
  55: mtma:   0

Defined functions