1 .title M9312 'DD' BOOT prom for TU58 DECtapeII serial tape controller (REVISED) 2 3 ; This source code is an M9312 boot PROM for the TU58 version 23-765B9. 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 ; The original code in 23-765A9 is REALLY BROKEN when it comes to 21 ; supporting a non-std CSR other than 776500 in R1 on entry 22 ; 23 ; All the hard references to: ddrbuf, ddxcsr, ddxbuf 24 ; have been changed to: 2(R1), 4(R1), 6(R1) 25 ; 26 ; The one reference where 'ddrcsr' might have been used is '(R1)' instead 27 ; which is actually correct (but totally inconsistent with other usage). 28 ; 29 ;AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 30 31 32 176500 ddcsr =176500 ; std TU58 csrbase 33 34 000000 ddrcsr =+0 ; receive control 35 000002 ddrbuf =+2 ; receive data 36 000004 ddxcsr =+4 ; transmit control 37 000006 ddxbuf =+6 ; transmit data 38 39 165564 diags =165564 ; console diags phase2 entry 40 41 .asect 42 173000 .=173000 43 44 ; -------------------------------------------------- 45 46 173000 104 104 start: .ascii "DD" ; device code (reversed) 47 48 173002 000176 .word last-. ; offset to next boot header 49 50 173004 000261 dd0n: sec ; boot std csr, unit zero, no diags 51 173006 012700 000000 dd0d: mov #0,r0 ; boot std csr, unit zero, with diags 52 173012 012701 176500 ddNr: mov #ddcsr,r1 ; boot std csr, unit 53 173016 010704 ddNb: mov pc,r4 ; boot csr , unit 54 173020 103055 bcc diag ; br if diags requested 55 173022 000402 br go ; return to (R4)+2 from diags 56 ; then skip over pseudo reboot vector 57 58 ; -------------------------------------------------- 59 60 173024 173000 .word 173000 ; prom start addess @ 24 61 173026 000340 .word 340 ; and priority level @ 26 62 63 ; -------------------------------------------------- 64 65 173030 012706 002000 go: mov #2000,sp ; setup a stack 66 173034 005004 clr r4 ; zap old return address 67 173036 005261 000004 inc ddxcsr(r1) ; set break bit 68 173042 005003 clr r3 ; data 000,000 69 173044 004767 173120' jsr pc,10$ ; transmit a bunch of zero chars 70 173050 005061 000004 clr ddxcsr(r1) ; clear break bit 71 173054 005761 000002 tst ddrbuf(r1) ; read/flush any stale rx char 72 173060 012703 004004 mov #<010*400>+004,r3 ; data 010,004 73 173064 004767 173124' jsr pc,12$ ; transmit 004 (init) and 010 (boot) 74 173070 010003 mov r0,r3 ; get unit number 75 173072 004767 173126' jsr pc,13$ ; transmit unit number 76 77 173076 005003 clr r3 ; clear rx buffer ptr 78 173100 105711 2$: tstb (r1) ; wait for rcv'd char available 79 173102 100376 bpl 2$ ; br if not yet 80 173104 116123 000002 movb ddrbuf(r1),(r3)+ ; store the char in buffer, bump ptr 81 173110 022703 001000 cmp #1000,r3 ; hit end of buffer (512. bytes)? 82 173114 101371 bhi 2$ ; br if not yet 83 84 173116 005007 clr pc ; jump to bootstrap at zero 85 86 173120 004717 10$: jsr pc,(pc) ; recursive call for char replication 87 173122 004717 11$: jsr pc,(pc) ; recursive call for char replication 88 173124 004717 12$: jsr pc,(pc) ; recursive call for char replication 89 173126 105761 000004 13$: tstb ddxcsr(r1) ; wait for xmit buffer available 90 173132 100375 bpl 13$ ; br if not yet 91 173134 110361 000006 movb r3,ddxbuf(r1) ; send the char 92 173140 000303 swab r3 ; swap to other char 93 173142 000207 rts pc ; now recurse or return 94 95 ; -------------------------------------------------- 96 97 173144 000261 dd1n: sec ; boot std csr, unit one, no diags 98 173146 012700 000001 dd1d: mov #1,r0 ; boot std csr, unit one, with diags 99 173152 000717 br ddNr ; continue 100 101 ; -------------------------------------------------- 102 103 173154 000137 165564 diag: jmp @#diags ; jump to console diags 104 105 ; -------------------------------------------------- 106 107 173160 000000 000000 000000 .word 0,0,0,0,0,0,0 ; unused 173166 000000 000000 000000 173174 000000 108 109 ; -------------------------------------------------- 110 111 173176 .=start+176 112 173176 046154 crc16: .word <046154> ; CRC-16 will go here 113 114 last: ; next boot prom starts here 115 116 .end 116