Annotation of 42BSD/sys/mdec/mttoggle.s, revision 1.1.1.1

1.1       root        1: /*     mttoggle.s      6.1     83/07/29        */
                      2: 
                      3: /*
                      4:  * Prototype toggle in bootstrap code for mt type tapes.
                      5:  * If on anything but a 780 with a tape at drive 0 of mba 1
                      6:  * this will have to be repaired by patching mba and mt.
                      7:  */
                      8:        movl    mba,r10
                      9:        mull3   mt,$0x80,r11
                     10:        addl3   r11,r10,r11
                     11:        addl2   $0x400,r11
                     12:        movzbl  $1,4(r10)
                     13:        movzbl  $4,8(r11)               /* drive zero, one record */
                     14:        clrl    12(r10)                 /* set address to zero */
                     15:        movl    $0x80000000,0x800(r10)  /* validate map register */
                     16:        cvtwl   $-512,16(r10)           /* set byte count */
                     17:        movzwl  $512,20(r11)            /* set byte count */
                     18: 0:
                     19:        movl    0x44(r11),r0
                     20:        bbc     $15,r0,0b
                     21:        movzbl  $071,(r11)              /* read forward, go */
                     22:        halt
                     23:        .align  2
                     24: mba:   .long   0x20012000
                     25: mt:    .long   0

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