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Annotation of 43BSDTahoe/sys/mdec/mttoggle.s, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1980, 1986 Regents of the University of California.
                      3:  * All rights reserved.  The Berkeley software License Agreement
                      4:  * specifies the terms and conditions for redistribution.
                      5:  */
                      6: 
                      7: #ifndef lint
                      8: _sccsid:.asciz "@(#)mttoggle.s 7.1 (Berkeley) 6/5/86"
                      9: #endif not lint
                     10: 
                     11: /*
                     12:  * Prototype toggle in bootstrap code for mt type tapes.
                     13:  * If on anything but a 780 with a tape at drive 0 of mba 1
                     14:  * this will have to be repaired by patching mba and mt.
                     15:  */
                     16:        movl    mba,r10
                     17:        mull3   mt,$0x80,r11
                     18:        addl3   r11,r10,r11
                     19:        addl2   $0x400,r11
                     20:        movzbl  $1,4(r10)
                     21:        movzbl  $4,8(r11)               /* drive zero, one record */
                     22:        clrl    12(r10)                 /* set address to zero */
                     23:        movl    $0x80000000,0x800(r10)  /* validate map register */
                     24:        cvtwl   $-512,16(r10)           /* set byte count */
                     25:        movzwl  $512,20(r11)            /* set byte count */
                     26: 0:
                     27:        movl    0x44(r11),r0
                     28:        bbc     $15,r0,0b
                     29:        movzbl  $071,(r11)              /* read forward, go */
                     30:        halt
                     31:        .align  2
                     32: mba:   .long   0x20012000
                     33: mt:    .long   0

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