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

/*      uttoggle.s      6.1     83/07/29        */

/*
 * Prototype toggle in bootstrap code for ut 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   $0172440,r2
        movw    $0x04c0,26(r2)          /* set tape density & format */
        mnegw   $512,6(r2)              /* set frame count */
        mnegw   $256,2(r2)              /* set word count */
        clrw    4(r2)                   /* set bus address */
        movw    $0x39,(r2)              /* set command and go */
        halt
        .align  2
uba:    .long   0x20006000
umem:   .long   0x2013e000