1 .title M9312 'DD' BOOT prom for TU58 DECtapeII serial tape controller 2 3 ; This source code is an exact copy of the DEC M9312 23-765A9 boot PROM. 4 ; 5 ; This boot PROM is for the TU58 DECtapeII serial tape 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 18 ;VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV 19 ; 20 ; This code is REALLY BROKEN when it comes to supporting a non-std CSR. 21 ; All the references to: ddrbuf, ddxcsr, ddxbuf 22 ; should be changed to: 2(R1), 4(R1), 6(R1) 23 ; The one reference where 'ddrcsr' might have been used is '(R1)' instead 24 ; which is actually correct (but totally inconsistent with other usage). 25 ; 26 ; ANY attempt to enter this bootstrap with a non-std CSR address in R1 27 ; will fail to boot correctly at all, and will likely hang the system 28 ; OR cause an unexpected timeout trap if address 776500 does not exist. 29 ; 30 ;AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 31 32 33 176500 ddcsr =176500 ; std TU58 csrbase 34 35 176500 ddrcsr =ddcsr+0 ; receive control 36 176502 ddrbuf =ddcsr+2 ; receive data 37 176504 ddxcsr =ddcsr+4 ; transmit control 38 176506 ddxbuf =ddcsr+6 ; transmit data 39 40 165564 diags =165564 ; console diags phase2 entry 41 42 .asect 43 173000 .=173000 44 45 ; -------------------------------------------------- 46 47 173000 104 104 start: .ascii "DD" ; device code (reversed) 48 49 173002 000176 .word last-. ; offset to next boot header 50 51 173004 000261 dd0n: sec ; boot std csr, unit zero, no diags 52 173006 012700 000000 dd0d: mov #0,r0 ; boot std csr, unit zero, with diags 53 173012 012701 176500 ddNr: mov #ddcsr,r1 ; boot std csr, unit 54 173016 010704 ddNb: mov pc,r4 ; boot csr , unit 55 173020 103054 bcc diag ; br if diags requested 56 173022 000402 br go ; return to (R4)+2 from diags 57 ; then skip over pseudo reboot vector 58 59 ; -------------------------------------------------- 60 61 173024 173000 .word 173000 ; prom start addess @ 24 62 173026 000340 .word 340 ; and priority level @ 26 63 64 ; -------------------------------------------------- 65 66 173030 012706 002000 go: mov #2000,sp ; setup a stack 67 173034 005004 clr r4 ; zap old return address 68 173036 012702 176504 mov #ddxcsr,r2 ; addr of transmit control reg 69 173042 005212 inc (r2) ; set break bit 70 173044 005003 clr r3 ; data 000,000 71 173046 004767 173120' jsr pc,10$ ; transmit a bunch of zero chars 72 173052 005012 clr (r2) ; clear break bit 73 173054 005737 176502 tst @#ddrbuf ; read/flush any stale rx char 74 173060 012703 004004 mov #<010*400>+004,r3 ; data 010,004 75 173064 004767 173124' jsr pc,12$ ; transmit 004 (init) and 010 (boot) 76 173070 010003 mov r0,r3 ; get unit number 77 173072 004767 173126' jsr pc,13$ ; transmit unit number 78 79 173076 005003 clr r3 ; clear rx buffer ptr 80 173100 105711 2$: tstb (r1) ; wait for rcv'd char available 81 173102 100376 bpl 2$ ; br if not yet 82 173104 113723 176502 movb @#ddrbuf,(r3)+ ; store the char in buffer, bump ptr 83 173110 022703 001000 cmp #1000,r3 ; hit end of buffer (512. bytes)? 84 173114 101371 bhi 2$ ; br if not yet 85 86 173116 005007 clr pc ; jump to bootstrap at zero 87 88 173120 004717 10$: jsr pc,(pc) ; recursive call for char replication 89 173122 004717 11$: jsr pc,(pc) ; recursive call for char replication 90 173124 004717 12$: jsr pc,(pc) ; recursive call for char replication 91 173126 105712 13$: tstb (r2) ; wait for xmit buffer available 92 173130 100376 bpl 13$ ; br if not yet 93 173132 110337 176506 movb r3,@#ddxbuf ; send the char 94 173136 000303 swab r3 ; swap to other char 95 173140 000207 rts pc ; now recurse or return 96 97 ; -------------------------------------------------- 98 99 173142 000261 dd1n: sec ; boot std csr, unit one, no diags 100 173144 012700 000001 dd1d: mov #1,r0 ; boot std csr, unit one, with diags 101 173150 000720 br ddNr ; continue 102 103 ; -------------------------------------------------- 104 105 173152 000137 165564 diag: jmp @#diags ; jump to console diags 106 107 ; -------------------------------------------------- 108 109 173156 000000 000000 000000 .word 0,0,0,0,0,0,0,0 ; unused 173164 000000 000000 000000 173172 000000 000000 110 111 ; -------------------------------------------------- 112 113 173176 .=start+176 114 173176 125025 crc16: .word <125025> ; CRC-16 will go here 115 116 last: ; next boot prom starts here 117 118 .end 118