1 /FLOPPY DISK (RX01,RX71) SYSTEM HANDLER FOR OS/8
11 /COPYRIGHT (C) 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
45 \f/FLOPPY DISK HANDLER SYSTEM
47 /DEFINITIONS OF RX8/E IOT'S
51 DEVCOD= 750 /DEVICECODE
53 LCD= 6001+DEVCOD /LOAD COMMAND REGISTER
54 XDR= 6002+DEVCOD /TRANSFER DATA REGISTER
55 STR= 6003+DEVCOD /SKIP ON TRANSFER REQUEST FLAG, CLEAR FLAG
56 SER= 6004+DEVCOD /SKIP ON ERROR FLAG, CLEAR FLAG
57 SDN= 6005+DEVCOD /SKIP ON DONE FLAG, CLEAR FLAG
58 INTR= 6006+DEVCOD /INTERRUPT ENABLE/DISABLE
59 INIT= 6007+DEVCOD /INITIALIZE CONTROLLER AND RECALIBRATE DRIVES
62 /NOTES ON THIS HANDLER:
64 /THIS HANDLER READS AND WRITES THE DISK IN "12-BIT" MODE, IN WHICH
65 /ONLY 6 BITS OF EVERY 8-BIT BYTE ARE USED. AN RX01 CARTRIDGE
66 /CONTAINS 494 OS/8 BLOCKS UNDER THIS METHOD
68 /TO MAXIMIZE SPEED ON THE DEVICE, THE HANDLER READS AND WRITES DATA
69 /ON A TRACK WITH A TWO-WAY INTERLEAVE - I.E. RECORDS 1-26 ON A TRACK
70 /ARE WRITTEN IN THE SEQUENCE:
71 / 1,3,5,7,9,11,13,15,17,19,21,23,25,2,4,6,8,10,12,14,16,18,20,22,24,26
73 /IN THIS WAY THE HANDLER CAN TRANSFER DATA AT A 5KHZ WORD RATE
74 /MAIN CHANGE FROM RX01SY IS THAT THE NEXT DISK ADDRESS IS
75 /CALCULATED DURING THE DATA TARNSFER TO/FROM THE DISK TO ITS
76 /SECTOR BUFFER. THIS IS NEEDED FOR SLOW 8S !.
77 \f *0 /ORIGIN FOR BUILD
80 DEVICE RX8E /"RX8E" IS THE GROUP NAME
81 DEVICE SYS /"SYS" IS THE ENTRY POINT NAME
82 4250 /DCB WORD - DEVICE TYPE 25, DIRECTORY DEVICE
83 2007 /2000 MEANS SYS HANDLER,7 IS ENTRY POINT OFFSET
84 0 /THIS WORD ALWAYS SEEMS TO BE 0
86 76^26%4 /THE NUMBER OF OS8 BLOCKS ON THE DEVICE
89 BOOTST-BOOTND /LENGTH OF THE BOOTSTRAP
106 XR, 7600+BOOTND-BOOTST-1 /LOC 17
176 ZBLOCK 7 /SYSTEM SPACE
180 / LINK REMAINS 0 THROUGH THE MAIN PROCESSING LOOP
181 / EXCEPT AS MANIPULATED BY DIVSUB
183 / OVERALL LOOP CONTROL THROUGH BC IS MILDLY ODD.
184 / BC STARTS WITH MINUS COUNT OF THE # OF WORDS TO BE TRANSFERRED.
185 / BC IS INCREMENTED 77 TIMES AT THE SILO CODE, AND 1 TIME AFTER
187 / A READ OPERATION STARTS AND FINISHES AT THE MIDDLE OF THE LOOP.
188 / A WRITE OEPRATION STARTS AT THE TOP, AND FINISHES AT BOTTOM.
189 / THUS, A 1 BLOCK READ INCREMENTS 1, 77, 1, 77 AND EXITS FROM MIDDLE.
190 / AND, A 1 BLOCK WRITE INCREMENTS 77, 1, 77, 1 AND EXITS FROM BOTTOM.
192 / DIVISION IS CARRIED OUT IN PARALLEL WITH I/O OPERATION BECAUSE OF
193 / TIMING CONSIDERATIONS OF THE VT78.
195 / THERE IS NO ERROR RETRY, NOT PARTICULARLY CRITICAL FOR A FLOPPY.
198 CLL CML CLA RAR /SET LINK=0, AC=4000
199 TAD I SYS /TO PUT READ-WRITE BIT TO LINK
200 S33, AND S70 /KEEP BITS FOR CDF
201 TAD SCDF0 /ADDING IN CDF LITERAL
202 DCA BUFCDF /CDF INSTRUCTION TO USER'S BUFFER
203 CML RTL /FUNCTION CODE, 0=WRITE, 2=READ
205 RDF /FETCH CALLER'S FIELD
206 TAD SCDIF0 /MAKE CDF CIF TO HIS FIELD
208 TAD I SYS /MAKE CONTROL COUNT
209 S4UNIT, RAL /7004 (7024 FOR UNIT #1) DOUBLES AS
210 /LITERAL FOR READ-WRITE COMMAND
211 AND S7600 /MAKE CONTROL COUNT FOR TOTAL
215 TAD I SYS /FETCH BUFFER ADDRESS
218 S70, 70 /THIS LITERAL MUST BE AT LOCATION 33!
219 IFNZRO S70&177-33 <.ERROR.>
220 TAD I SYS /OS8 BLOCK #
221 CLL RTL /TIMES 4 TO BE FLOPPY SECTOR #
223 ISZ SYS /ERROR EXIT FROM I/O CALL
224 JMS DIVSUB /COMPUTE TRACK/SECTOR FOR FIRST I/O
225 TAD FN /READ OR WRITE START DIFFERENTLY
226 SZA CLA /SKIP ON WRITE
227 JMP STREAD /GO TO READ
229 / WRITE FALLS THRU.......
233 / TOP OF MAIN PROCESSING LOOP
235 SETSLO, TAD FN /SET SILO TO LOAD-UNLOAD DEPENDING
237 TAD S7700 /SILO CONTROL COUNT 100 OCTAL
239 BUFCDF, HLT /CDF TO USER'S BUFFER PLACED HERE
240 TRLOOP, TAD I BUF /FETCH A WORD IN CASE WRITE
243 XDR /AC TO SILO; OR; SILO TO AC
244 DCA I BUF /PLACE A WORD IN CASE READ; WRITE REPLACES SAME.
245 ISZ BUF /MOVE TO NEXT BUFFER LOCATION (MAY SKIP)
246 S77, 77 /LITERAL 77, EXECUTES AS A NOP
247 ISZ FLPWC /DONE WITH 100 OCTAL SILO OPERATION
249 TAD BC /INCREMENT BC BY 77 HERE, AND 1 LATER
251 MAGIC, SNA /SKIP UNLESS READ DONE;NO-OP FOR LDCMD!
255 / MIDDLE OF MAIN PROCESSING LOOP
257 STREAD, TAD FN /READ STARTS HERE
258 TAD S4UNIT /SET UP DO DO READ OR WRITE I/O
260 TAD MQ /LOAD PRECOMPUTED SECTOR INFO
262 JMP .-1 /IN CASE NOT READY
264 S7700, 7700 /CLEAR AC, CAN'T SKIP (XDR LEAVES AC ALONE)
266 STR /ILLEGAL 7700 ENTRY WILL HANG; THE FUNCTION
267 JMP .-1 /IS NOT SET UP (LDCMD)
270 ISZ REC /MOVE TO NEXT FLOPPY SECTOR
271 JMS DIVSUB /COMPUTE NEXT TRACK AND SECTOR DURING THIS I/O
272 TAD MAGIC /WAIT FOR I/O TO COMPLETE
274 ISZ BC /CHECK FOR WRITE EXIT
275 JMP SETSLO /NO, BACK TO TOP
276 OKEX, ISZ SYS /BUMP TO REGULAR EXIT
277 SRET, HLT /CDF CIF FOR USER'S CALLING FIELD
290 / MUST ENTER WITH LINK AND AC 0
291 / COMPUTES TRACK IN 'QUO', SECTOR IN 'MQ', FROM # IN 'REC'
293 / REPEATED SUBTRACTS OF 13 DECIMAL LEAVE THE HIGH N-1 BITS OF
294 / QUOTIENT IN QUO, THE LOW BIT OF QUOTIENT IN LINK, AND THE
295 / REMAINDER IN AC. THE INTERLEAVE IS ACCOMPLISHED BY SHIFTING
296 / LOW QUOTINET BIT INTO LOW REMAINDER BIT.
299 DCA QUO /INIT QUOTIENT FOR DIVIDE
300 TAD REC /RECORD # MASSAGED IN AC
301 DIVLP, SNL /LINK USAGE REVERSED FROM RICHIE'S CODE
302 ISZ QUO /ISZ EVERY OTHER TIME, ==DIVIDE BY 26
303 TAD SM15 /THE -13 DECIMAL
306 RAL /LINK USAGE REVERSED; INTERLEAVE!!
307 TAD S33 /ADD 233 (200 IRREL) MAKING SECTOR
309 JMP I DIVSUB /LEAVING LINK AND AC 0
313 FLPWC=. /COUNTER IN ENTRY POINT FOR SILO LOOP ONLY
317 LCD /COMMAND FROM AC, WHICH IS CLEARED
318 SER /SKIP IF ERROR (I/O ONLY)
319 JMP I LDCMD /OK, RETURN
320 CLL CML CLA RAR /CONVENTIONAL ERROR RETURN 4000 IN AC
321 JMP SRET /SET CDF AND EXIT
323 / USE DATA BREAK LOCATIONS FOR TERMPORARIES