1 .title M9312 'DY' BOOT prom for RX211 compatible controller 2 3 ; This source code is an exact copy of the DEC M9312 23-811A9 boot PROM. 4 ; 5 ; This boot PROM is for any RX211/RX02 compatible floppy controller. 6 ; 7 ; Multiple units and/or CSR addresses are supported via different entry points. 8 ; 9 ; Standard devices are 82S131, Am27S13, 74S571 or other compatible bipolar 10 ; PROMs with a 512x4 TriState 16pin DIP architecture. This code resides in 11 ; the low half of the device; the top half is blank and unused. 12 ; 13 ; Alternatively, 82S129 compatible 256x4 TriState 16pin DIP devices can be 14 ; used, as the uppermost address line (hardwired low) is an active low chip 15 ; select (and will be correctly asserted low). 16 17 177170 rxcsr =177170 ; std RX211 csrbase 18 19 000000 rxcs =+0 ; command/status 20 000002 rxdb =+2 ; data buffer 21 22 165564 diags =165564 ; console diags phase2 entry 23 24 000000 .asect 25 173000 .=173000 26 27 ; -------------------------------------------------- 28 29 173000 131 104 start: .ascii "YD" ; device code (reversed) 30 31 173002 000176 .word last-. ; offset to next boot header 32 33 173004 000261 dy0n: sec ; boot std csr, unit zero, no diags 34 173006 012700 000000 dy0d: mov #0,r0 ; boot std csr, unit zero, with diags 35 173012 012701 177170 dyNr: mov #rxcsr,r1 ; boot std csr, unit 36 173016 010704 dyNb: mov pc,r4 ; boot csr , unit 37 173020 103064 bcc diag ; br if diags requested 38 173022 000402 br go ; return to (R4)+2 from diags 39 ; then skip over pseudo reboot vector 40 41 ; -------------------------------------------------- 42 43 173024 173000 .word 173000 ; prom start addess @ 24 44 173026 000340 .word 340 ; and priority level @ 26 45 46 ; -------------------------------------------------- 47 48 173030 005103 go: com r3 ; complement density flag 49 173032 000005 reset ; clear all device registers 50 173034 012704 000401 mov #401,r4 ; sector 1 and track 1 51 173040 005002 clr r2 ; init buffer address 52 173042 012705 000200 mov #200,r5 ; assume double density 53 173046 042703 177377 bic #^c400,r3 ; single density? 54 173052 001001 bne 2$ ; br if not 55 173054 006205 asr r5 ; adjust for single density 56 173056 050700 2$: bis pc,r0 ; bis #173x60,r0 + r0=0/1 => r0=173x60/173x61 57 173060 156003 000036 bisb 4$-.(r0),r3 ; bis 007(unit0) or 027(unit1) into r3 58 173064 040700 bic pc,r0 ; bic #173x66,r0 59 173066 010706 mov pc,sp ; mov #3$,sp: init state to step1 60 173070 000423 3$: br 7$ ; step1 61 173072 000432 br 9$ ; step2 62 173074 000416 br 6$ ; step3 63 173076 000415 br 6$ ; step4 64 173100 000425 br 8$ ; step5 65 173102 000430 br 10$ ; step6 66 173104 000407 br 5$ ; step7 67 173106 060502 add r5,r2 ; address += 2 68 173110 060502 add r5,r2 ; 69 173112 122424 cmpb (r4)+,(r4)+ ; sector += 2 70 173114 120427 cmpb r4,(pc)+ ; cmpb r4,#007; last sector read? 71 173116 007 027 4$: .byte 007,027 ; unit in <4>, read+go in <2:0> 72 173120 003756 ble 2$ ; br if more to read 73 74 173122 005007 clr pc ; jump to bootstrap at zero 75 76 173124 010261 000002 5$: mov r2,rxdb(r1) ; set bus address 77 173130 000403 br 7$ ; more 78 79 173132 110461 000002 6$: movb r4,rxdb(r1) ; set sector or track 80 173136 000304 swab r4 ; swap sector/track 81 82 173140 032711 100240 7$: bit #100240,(r1) ; wait for error<15>, treq<7>, or done<5> 83 173144 001775 beq 7$ ; keep looping, no bits set 84 173146 100730 bmi go ; retry if error bit set 85 173150 005726 tst (sp)+ ; flush one word off list 86 173152 000116 jmp (sp) ; go execute step1..step7 87 88 173154 042703 000004 8$: bic #4,r3 ; change to empty+go 89 173160 010311 9$: mov r3,(r1) ; set command 90 173162 000766 br 7$ ; more 91 92 173164 110561 000002 10$: movb r5,rxdb(r1) ; set ? to 1 93 173170 000763 br 7$ ; more 94 95 ; -------------------------------------------------- 96 97 173172 000137 165564 diag: jmp @#diags ; jump to console diags 98 99 ; -------------------------------------------------- 100 101 173176 .=start+176 102 173176 057141 crc16: .word <057141> ; CRC-16 will go here 103 104 last: ; next boot prom starts here 105 106 .end 106 Symbol table . =****** 5$0 =173124 L CRC16 =173176 DYNB =173016 RXCSR =177170 10$0 =173164 L 6$0 =173132 L DIAG =173172 DYNR =173012 RXDB =000002 2$0 =173056 L 7$0 =173140 L DIAGS =165564 GO =173030 START =173000 3$0 =173070 L 8$0 =173154 L DY0D =173006 LAST =173200 4$0 =173116 L 9$0 =173160 L DY0N =173004 RXCS =000000 Program sections: . ABS. 173200 000 (RW,I,GBL,ABS,OVR,NOSAV) 000000 001 (RW,I,LCL,REL,CON,NOSAV)