File:  [CSRG BSD Unix] / 42BSD / sys / mdec / mttoggle.s
Revision 1.1.1.1 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:12:53 2018 UTC (8 years, 1 month ago) by root
Branches: MAIN, BSD
CVS tags: HEAD, BSD42
BSD 4.2

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

/*
 * Prototype toggle in bootstrap code for mt type tapes.
 * If on anything but a 780 with a tape at drive 0 of mba 1
 * this will have to be repaired by patching mba and mt.
 */
	movl	mba,r10
	mull3	mt,$0x80,r11
	addl3	r11,r10,r11
	addl2	$0x400,r11
	movzbl	$1,4(r10)
	movzbl	$4,8(r11)		/* drive zero, one record */
	clrl	12(r10)			/* set address to zero */
	movl	$0x80000000,0x800(r10)	/* validate map register */
	cvtwl	$-512,16(r10)		/* set byte count */
	movzwl	$512,20(r11)		/* set byte count */
0:
	movl	0x44(r11),r0
	bbc	$15,r0,0b
	movzbl	$071,(r11)		/* read forward, go */
	halt
	.align	2
mba:	.long	0x20012000
mt:	.long	0

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