1                                	.title	M9312 'DK/DT' BOOT prom for RK03/05 and TU55/56 controllers
       2                                
       3                                	; This source code is a modified copy of the DEC M9312 23-756A9 boot PROM.
       4                                	;
       5                                	; This boot PROM is for the RK03/05 DECdisk controllers.
       6                                	;
       7                                	; Multiple units and/or CSR addresses are supported via different entry points.
       8                                
       9 177400                         rkcsr	=177400				; std RK03/05 DECdisk csrbase
      10                                
      11 000002                         rkwc	=+6-4				; word count
      12 000006                         rkda	=+12-4				; disk address
      13                                
      14 000002                         xxwc	=rkwc				; common word count offset
      15                                
      16                                	.asect
      17                                	; ---- Simple boot drive 0 from 0
      18 000000                         	. = 0
      19 000000 000137  010000          	jmp	@#start0
      20                                
      21                                	; ---- Reboot drive 0 on power event
      22 000024                         	. = 24				; Power ON/OFF
      23 000024 010000                  	.word	     start0		; PC
      24 000026 000340                  	.word	     340		; PSW priority level 7
      25                                
      26                                
      27                                	; ----- Main boot addresses
      28 010000                         	.=10000 			;  arbitrary position > 3000
      29                                
      30                                start:
      31                                	; 8 unit numbers => 8 entry addresses
      32                                start0:
      33 010000 012700  000000          	mov	#0,r0
      34 010004 000435                  	br	dknr
      35 010006 000240                  	nop
      36                                start1:
      37 010010 012700  000001          	mov	#1,r0
      38 010014 000431                  	br	dknr
      39 010016 000240                  	nop
      40                                start2:
      41 010020 012700  000002          	mov	#2,r0
      42 010024 000425                  	br	dknr
      43 010026 000240                  	nop
      44                                start3:
      45 010030 012700  000003          	mov	#3,r0
      46 010034 000421                  	br	dknr
      47 010036 000240                  	nop
      48                                start4:
      49 010040 012700  000004          	mov	#4,r0
      50 010044 000415                  	br	dknr
      51 010046 000240                  	nop
      52                                start5:
      53 010050 012700  000005          	mov	#5,r0
      54 010054 000411                  	br	dknr
      55 010056 000240                  	nop
      56                                start6:
      57 010060 012700  000006          	mov	#6,r0
      58 010064 000405                  	br	dknr
      59 010066 000240                  	nop
      60                                start7:
      61 010070 012700  000007          	mov	#7,r0
      62 010074 000401                  	br	dknr
      63 010076 000240                  	nop
      64                                
      65                                
      66                                dknr:
      67 010100 012701  177404          	mov	#rkcsr+4,r1		; boot std csr, unit <R0>
      68                                
      69 010104 010003                  	mov	r0,r3			; get unit number
      70 010106 000241                  	clc				; C=0 for ror
      71 010110 006003                  	ror	r3			; shift into 15:12
      72 010112 006003                  	ror	r3			;
      73 010114 006003                  	ror	r3			;
      74 010116 006003                  	ror	r3			;
      75 010120 010361  000006          	mov	r3,rkda(r1)		; unit number, sector 0 to disk addr
      76                                
      77 010124 012761  177000  000002  	mov	#-512.,xxwc(r1)		; set word count
      78 010132 052703  000005          	bis	#5,r3			; command READ+GO
      79 010136 010311                  	mov	r3,(r1)			; execute
      80 010140 105711                  2$:	tstb	(r1)			; test ready
      81 010142 100376                  	bpl	2$			; loop
      82                                
      83 010144 005711                  	tst	(r1)			; check error
      84 010146 100002                  	bpl	3$			; br if no error
      85                                
      86 010150 000005                  	reset				; reset the world
      87 010152 000752                  	br     dknr			; and retry
      88                                
      89 010154 042711  000377          3$:	bic	#377,(r1)		; nop command
      90 010160 005007                  	clr	pc			; jump to loaded boot sector
      91                                
      92                                	.end
      92