1 /4 TD8E HANDLER FOR BUILD..TD8E-B
11 /COPYRIGHT (C) 1974,1975,1977 BY DIGITAL EQUIPMENT CORPORATION
22 /THE INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE
23 /AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
24 /CORPORATION. DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY
25 /FOR ANY ERRORS THAT MAY APPEAR IN THIS DOCUMENT.
27 /THE SOFTWARE DESCRIBED IN THIS DOCUMENT IS FURNISHED TO THE PURCHASER
28 /UNDER A LICENSE FOR USE ON A SINGLE COMPUTER SYSTEM AND CAN BE COPIED
29 /(WITH INCLUSION OF DIGITAL'S COPYRIGHT NOTICE) ONLY FOR USE IN SUCH
30 /SYSTEM, EXCEPT AS MAY OTHERWISE BE PROVIDED IN WRITING BY DIGITAL.
32 /DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY FOR THE USE
33 /OR RELIABILITY OF ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY
47 DEVICE TD8B;DEVICE DTA2;4210;4011;ZBLOCK 2
48 DEVICE TD8B;DEVICE DTA3;4210;4015;ZBLOCK 2
50 SDSS=6761 /SKIP ON SINGLE LINE FLAG
51 SDST=6762 /SKIP ON TIME ERROR
52 SDSQ=6763 /SKIP ON QUAD LINE FLAG
53 SDLC=6764 /LOAD TAPE COMMAND REGISTER
54 SDLD=6765 /LOAD DATA REGISTER
55 SDRC=6766 /READ COMMAND REGISTER
56 SDRD=6767 /READ DATA REGISTER
62 /1. VERSION # IS NOW 1
63 /2. PARITY ^C IS NOW LEGAL
64 /3. ^C CHECK NO LONGER ADVANCES READER
66 /MAINTENANCE RELEASE CHANGES:
69 /5. MADE CODE IMPROVEMENTS
76 NXINIT, 7600 /CLEAR AC HERE!!!
84 BUFF, 4000 /MUST BE NEGATIVE INITIALLY
87 DTA0, TDVERSION /ENTRY FOR UNIT 0
91 DTA1, TDVERSION /ENTRY FOR UNIT 1
94 DCA DTA0 /PICK UP ARGS AT DTA0
96 DCA UNIT /UNIT # FROM LINK
99 DCA LEAVE /SET UP EXIT FROM HANDLER
102 DCA FUNCT /SAVE FUNCTION WORD
105 C200, AND CM200 /GET A PAGE COUNT
108 C374, AND C70 /ISOLATE FIELD OF TRANSFER
111 ISZ DTA0 /POINT TO BUFFER
114 ISZ DTA0 /POINT TO RECORD
116 CLL RAL /CONVERT TO DECTAPE BLOCKS
118 ISZ DTA0 /POINT TO ERROR RET.
121 /THE RETURN FROM INIT ZEROES IT
123 DCA ERCNT /3 ERROR TRIES
126 JMS I CSELCT /CHECK FOR SELEC ERROR
127 JMP .-1 /LOOPS IF NO ^C AND SELECT ERROR
130 JMP GO /OK.. START THE SEARCH
131 TRWCOM, SDST /TIME OR CHECK SUM ERROR?
133 JMP TRY3 /YES TRY UP TO 3 TIMES
134 TAD PGCT /NO.. IS PAGE COUNT EXHAUSTED?
137 JMP EXIT /YES.. DONE THIS TRANSFER
138 DCA PGCT /NEW PAGE COUNT
141 TAD C200 /GET NEW BUFFER ADDRESS
143 CLL CML /FORCE FORWARD MOTION
144 GO, CLA CML RTR /PUT IN DIRECTION BIT
147 SDLC /INITIATE THE MOTION
148 JMS I CRDQAD /WAIT FOR 8 LINES TO PASS
150 M20, 7760 /DON'T CARE IF IT DOES SKIP!!!
151 TSRCH, SDSS /WAIT
\ f FOR BLOCK MARK OR END ZONE
154 CLL RTL /DIRECTION TO LINK, DATA TO AC 4-9
155 AND C374 /ISOLATE M.T BITS
156 TAD M110 /IS IT END ZONE?
158 JMP ENDZ /YES..DO SOMETHING REASONABLE
159 TAD M20 /HOW ABOUT BLOCK MARK?
161 JMP TSRCH /NEITHER..KEEP LOOKING
162 SDRD /WHAT IS THIS BLOCK'S #?
163 SZL /IF IN REVERSE, LOOK FOR 3 BEFORE
164 TAD TC3 /THE ACTUAL TARGET BLOCK
168 SNA /IS THIS THE BLOCK?
169 JMP TFOUND /YES..HAVE CORRECT ONE
170 M110, SZL SNA CLA /ARE WE HEADED PROPERLY?
171 JMP TSRCH /YES.. KEEP LOOKING
172 ENDZ, SDRC /IF WE ARE IN END ZONE FORWARD, WE LOSE
174 JMP GO /EXECUTE TURN AROUND AND SEARCH
176 ISZ ERCNT /TRIED 3 TIMES?
179 EXIT, ISZ DTA0 /NORMAL RETURN
181 FATAL, TAD UNIT /STOP TAPE FIRST
183 CLA CML RAR /EITHER 0 OR 4000 IN AC
184 LEAVE, HLT /GETS CIF CDF N
187 INIT, JMS . /FIND OUT WHERE WE GOT LOADED
189 SPA /NEGATIVE ENDS LIST
202 TFOUND, SZL CLA /ARE WE IN RIGHT DIRECTION
210 XFIELD, HLT /CONTROL 'TRICKLES THROUGH
222 CIF 0 /WE ARE IN FIELD 0
225 DCA XFUNCT /READ/WRITE TO FUNCTION
227 JMP .-1 /LOOK FOR REVERSE GUARD PATTERN
231 SZA CLA /IF NOT REV. GUARD, KEEP LOOKING
234 DCA WORDS /128 WORDS/BLOCK
236 K7700, SMA CLA /IS IT READ OR WRITE?
238 SDRC /CHECK FOR WRITE LOCKOUT
240 CLL /SETUP TO RETRY IF WRITE LOCK
242 JMP I CTRY3 /IF LOCKED OUT, ERROR
243 JMS R4LINE /SKIP A WORD
247 SDLC /TURN ON WRITE HEAD
249 JMS W4LINE /7777 IN REV. CHECKSUM
251 DCA CSUM /AND ALSO TAPE CHECKSUM
254 ISZ XBUFF /INCREMENT BUFF. ADD.
256 ISZ WORDS /DONE A BLOCK?
258 JMS W4LINE /A 129 TH WORD OF 0
259 JMS GCHK /GET 6 BIT CHECKSUM
260 JMS W4LINE /WRITE IT TO TAPE
261 JMS W4LINE /LET CHECK SUM FINISH
262 JMP I CRWCOM /SEE IF WE ARE FINISHED
265 JMS R4LINE /SKIP CONTROL WORDS
271 JMS EFUN /ADD WORD TO CHECKSUM
275 ISZ WORDS /DONE BLOCK?
278 JMS EFUN /CHECK SUM 129 TH WORD
280 AND K7700 /READ CHECKSUM
282 JMS GCHK /COMPARE TAPE AND OUR CHECKSUM
285 W4LINE, 0 /ADD TO CHECKSUM AND WRITE A 12 BIT
288 JMP .-1 /SKIP ON QUAD LINE FLAG
290 CLA /AC IS NOT CLEARED AFTER SDLD
293 R4LINE, 0 /WAIT FOR QUAD FLAG AND READ
299 EFUN, 0 /COMPUTE EQUIVALENCE CHECKSUM
301 DCA ETMP /ACTUALLY CHECKSUMS ON DECTAPE ARE
302 TAD ETMP /EQUIVALENCE OF ALL WORDS IN A RCORD
303 AND CSUM /6 BITS AT A TIME. SINCE EQUIVALENCE
304 CIA /IS ASSOCIATIVE WE DO IT 12 AT A TIME
305 CLL RAL /AND CONDENSE LATER.
306 TAD ETMP /IDENTITIES USED ARE:
307 TAD CSUM /A+B=(A.XOR.B)+2*(A.AND.B)
308 DCA CSUM /A.EQU.B=.NOT.(A.XOR.B)=A.XOR.(.NOT.B)
309 TAD ETMP /A.EQU.B=(A+(.NOT.B))-2*(A.AND.(.NOT.B))
313 \fGCHK, 0 /FORM 6 BIT CHECKSUM
325 INIT2, 0 /TIS INITIALIZES LOCS IN PAGE 2
328 JMP I INIT2 /0 ENDS LIST
330 DCA CTRY3 /UPDATE THE LIST
337 XBUFF, 0 /0 MUST TERMINATE IT!!
341 SELECT, 0 /THIS ROUTINE CHECKS FOR SELECT
342 TAD XUNIT /AND ^C TYPED
344 SDRC /GET STATUS AND SEE IF SELECT ERROR ON
347 ISZ SELECT /NOPE .TAKE NORMAL OUT
348 KSF /SEE IF FLAG IS UP
349 JMP I SELECT /NO..EXIT
352 TAD (-7603 /IS IT ^C?
354 JMP I SELECT /NO..EXIT