usr/src/sys/vax/mdec/tmtoggle.s

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifndef lint
_sccsid:.asciz  "@(#)tmtoggle.s 6.2 (Berkeley) %G%"
#endif not lint

/*
 * Prototype toggle in bootstrap code for tm type tapes.
 * If on anything but a 780 with the drive on uba0
 * this will have to be repaired by patching uba and umem.
 */
begin:
        movl    uba,r1
        movl    $0x80200000,0x800(r1)
        clrl    0x804(r1)
        movl    umem,r2
        bisl2   $0172520,r2
        mnegw   $512,4(r2)
        clrw    6(r2)
        movw    $03,2(r2)
        halt
        .align  2
uba:    .long   0x20006000
umem:   .long   0x2013e000