1 /4 TD8E HANDLER FOR BUILD..TD8E-D
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 TD8D;DEVICE DTA6;4210;4013;ZBLOCK 2
48 DEVICE TD8D;DEVICE DTA7;4210;4017;ZBLOCK 2
50 SDSS=6741 /SKIP ON SINGLE LINE FLAG
51 SDST=6742 /SKIP ON TIME ERROR
52 SDSQ=6743 /SKIP ON QUAD LINE FLAG
53 SDLC=6744 /LOAD TAPE COMMAND REGISTER
54 SDLD=6745 /LOAD DATA REGISTER
55 SDRC=6746 /READ COMMAND REGISTER
56 SDRD=6747 /READ DATA REGISTER
62 /1. VERSION # IS NOW 1
63 /2. PARITY ^C IS NOW LEGAL
64 /3. INITIALIZATION BUG FIXED
65 /4. ^C CHECK NO LONGER ADVANCES READER
67 /MAINTENANCE RELEASE CHANGES:
70 /6. MADE CODE IMPROVEMENTS
78 NXINIT, 7600 /CLEAR AC HERE!!!
79 JMS I CINIT2 /PART OF INITIALIZATION..DO THE PART
80 BASE2, DCA JINIT /ON SECOND PAGE AND THEN TO JINIT
91 DTA0, TDVERSION /ENTRY FOR UNIT 0
95 DTA1, TDVERSION /ENTRY FOR UNIT 1
98 DCA DTA0 /PICK UP ARGS AT DTA0
100 DCA UNIT /UNIT # FROM LINK
103 DCA LEAVE /SET UP EXIT FROM HANDLER
106 DCA FUNCT /SAVE FUNCTION WORD
109 C200, AND CM200 /GET A PAGE COUNT
112 C374, AND C70 /ISOLATE FIELD OF TRANSFER
115 ISZ DTA0 /POINT TO BUFFER
118 ISZ DTA0 /POINT TO RECORD
120 CLL RAL /CONVERT TO DECTAPE BLOCKS
122 ISZ DTA0 /POINT TO ERROR RET.
126 DCA ERCNT /3 ERROR TRIES
129 JMS I CSELCT /CHECK FOR SELEC ERROR
130 JMP .-1 /LOOPS IF NO ^C AND SELECT ERROR
133 JMP GO /OK.. START THE SEARCH
134 TRWCOM, SDST /TIME OR CHECK SUM ERROR?
136 JMP TRY3 /YES TRY UP TO 3 TIMES
137 TAD PGCT /NO.. IS PAGE COUNT EXHAUSTED?
140 JMP EXIT /YES.. DONE THIS TRANSFER
141 DCA PGCT /NEW PAGE COUNT
144 TAD C200 /GET NEW BUFFER ADDRESS
146 CLL CML /FORCE FORWARD MOTION
147 GO, CLA CML RTR /PUT IN DIRECTION BIT
150 SDLC /INITIATE THE MOTION
151 JMS I CRDQAD /WAIT FOR 8 LINES TO PASS
153 M20, 7760 /DON'T CARE IF IT DOES SKIP!!!
154 TSRCH, SDSS /WAIT
\ f FOR BLOCK MARK OR END ZONE
157 CLL RTL /DIRECTION TO LINK, DATA TO AC 4-9
158 AND C374 /ISOLATE M.T BITS
159 TAD M110 /IS IT END ZONE?
161 JMP ENDZ /YES..DO SOMETHING REASONABLE
162 TAD M20 /HOW ABOUT BLOCK MARK?
164 JMP TSRCH /NEITHER..KEEP LOOKING
165 SDRD /WHAT IS THIS BLOCK'S #?
166 SZL /IF IN REVERSE, LOOK FOR 3 BEFORE
167 TAD TC3 /THE ACTUAL TARGET BLOCK
171 SNA /IS THIS THE BLOCK?
172 JMP TFOUND /YES..HAVE CORRECT ONE
173 M110, SZL SNA CLA /ARE WE HEADED PROPERLY?
174 JMP TSRCH /YES.. KEEP LOOKING
175 ENDZ, SDRC /IF WE ARE IN END ZONE FORWARD, WE LOSE
177 JMP GO /EXECUTE TURN AROUND AND SEARCH
179 ISZ ERCNT /TRIED 3 TIMES?
182 EXIT, ISZ DTA0 /NORMAL RETURN
184 FATAL, TAD UNIT /STOP TAPE FIRST
186 CLA CML RAR /EITHER 0 OR 4000 IN AC
187 LEAVE, HLT /GETS CIF CDF N
190 INIT, JMS . /FIND OUT WHERE WE GOT LOADED
192 SPA /NEGATIVE ENDS LIST
203 TFOUND, SZL CLA /ARE WE IN RIGHT DIRECTION
211 XFIELD, HLT /CONTROL 'TRICKLES THROUGH
223 CIF 0 /WE ARE IN FIELD 0
226 DCA XFUNCT /READ/WRITE TO FUNCTION
228 JMP .-1 /LOOK FOR REVERSE GUARD PATTERN
232 SZA CLA /IF NOT REV. GUARD, KEEP LOOKING
235 DCA WORDS /128 WORDS/BLOCK
237 K7700, SMA CLA /IS IT READ OR WRITE?
239 SDRC /CHECK FOR WRITE LOCKOUT
241 CLL /SETUP TO RETRY IF WRITE LOCK
243 JMP I CTRY3 /IF LOCKED OUT, ERROR
244 JMS R4LINE /SKIP A WORD
248 SDLC /TURN ON WRITE HEAD
250 JMS W4LINE /7777 IN REV. CHECKSUM
252 DCA CSUM /AND ALSO TAPE CHECKSUM
255 ISZ XBUFF /INCREMENT BUFF. ADD.
257 ISZ WORDS /DONE A BLOCK?
259 JMS W4LINE /A 129 TH WORD OF 0
260 JMS GCHK /GET 6 BIT CHECKSUM
261 JMS W4LINE /WRITE IT TO TAPE
262 JMS W4LINE /LET CHECK SUM FINISH
263 JMP I CRWCOM /SEE IF WE ARE FINISHED
266 JMS R4LINE /SKIP CONTROL WORDS
272 JMS EFUN /ADD WORD TO CHECKSUM
276 ISZ WORDS /DONE BLOCK?
279 JMS EFUN /CHECK SUM 129 TH WORD
281 AND K7700 /READ CHECKSUM
283 JMS GCHK /COMPARE TAPE AND OUR CHECKSUM
286 W4LINE, 0 /ADD TO CHECKSUM AND WRITE A 12 BIT
289 JMP .-1 /SKIP ON QUAD LINE FLAG
291 CLA /AC IS NOT CLEARED AFTER SDLD
294 R4LINE, 0 /WAIT FOR QUAD FLAG AND READ
300 EFUN, 0 /COMPUTE EQUIVALENCE CHECKSUM
302 DCA ETMP /ACTUALLY CHECKSUMS ON DECTAPE ARE
303 TAD ETMP /EQUIVALENCE OF ALL WORDS IN A RCORD
304 AND CSUM /6 BITS AT A TIME. SINCE EQUIVALENCE
305 CIA /IS ASSOCIATIVE WE DO IT 12 AT A TIME
306 CLL RAL /AND CONDENSE LATER.
307 TAD ETMP /IDENTITIES USED ARE:
308 TAD CSUM /A+B=(A.XOR.B)+2*(A.AND.B)
309 DCA CSUM /A.EQU.B=.NOT.(A.XOR.B)=A.XOR.(.NOT.B)
310 TAD ETMP /A.EQU.B=(A+(.NOT.B))-2*(A.AND.(.NOT.B))
314 \fGCHK, 0 /FORM 6 BIT CHECKSUM
326 INIT2, 0 /TIS INITIALIZES LOCS IN PAGE 2
329 JMP I INIT2 /0 ENDS LIST
331 DCA CTRY3 /UPDATE THE LIST
338 XBUFF, 0 /0 MUST TERMINATE IT!!
342 SELECT, 0 /THIS ROUTINE CHECKS FOR SELECT
343 TAD XUNIT /AND ^C TYPED
345 SDRC /GET STATUS AND SEE IF SELECT ERROR ON
348 ISZ SELECT /NOPE .TAKE NORMAL OUT
349 KSF /SEE IF FLAG IS UP
350 JMP I SELECT /NO..EXIT
353 TAD (-7603 /IS IT ^C?
355 JMP I SELECT /NO..EXIT