Цитата:от: ДиMUSTый
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Исходный код аппле от 25 мая 1978 года.
***************************
* DISC-II *
* 13-SECTOR FORMAT *
* READ AND WRITE *
* SUBROUTINES *
* *
***************************
* *
* *
* COPYRIGHT 1978 *
* APPLE COMPUTER INC. *
* *
* ALL RIGHTS RESERVED *
* *
***************************
* *
* MAY 25, 1978 *
* WOZ *
* R. WIGGINTON *
* *
***************************
EJECT
***************************
* *
* CRITICAL TIMING *
* REQUIRES PAGE BOUND *
* CONSIDERATIONS FOR *
* CODE AND DATA *
* *
* -----CODE----- *
* *
* VIRTUALLY THE ENTIRE *
* 'WRITE' ROUTINE *
* MUST NOT CROSS *
* PAGE BOUNDARIES. *
* *
* CRITICAL BRANCHES IN *
* THE 'WRITE', 'READ', *
* AND 'READ ADR' SUBRS *
* WHICH MUST NOT CROSS *
* PAGE BOUNDARIES ARE *
* NOTED IN COMMENTS. *
* *
* -----DATA----- *
* *
* NBUF1, NBUF2, NBUF3, *
* NBUF4, AND NBUF5 ARE *
* 51-BYTE RAM BUFFERS *
* WHICH SHOULD ALL BE *
* LOCATED ON A SINGLE *
* PAGE BEGINNING WITH *
* NBUF1. (NBUF5 IS 52). *
* *
* NBUF6, NBUF7, AND *
* NBUF8 MUST NOT CROSS *
* PAGE BOUNDARIES AND *
* SHOULD BE LOCATED *
* ON A PAGE BEGINNING *
* WITH NBUF6. NBUF6 *
* AND NBUF7 ARE 51 BYTES *
* WHILE NBUF8 IS 52. *
* *
* NIBLIZING TABLE 'NIBL' *
* (32 BYTES) MUST NOT *
* CROSS PAGE BOUNDARY. *
* CONVERTS 5-BIT NIBLS *
* TO 7-BIT NIBLS. *
* *
* DENIBLIZING TABLE *
* 'DNIBL' MUST BE ON A *
* PAGE BOUNDARY, BUT *
* ONLY DNIBL,$AB TO *
* DNIBL,$FF NEED BE *
* USED. CONVERTS 7-BIT *
* NIBLS TO 5-BIT NIBLS. *
* *
***************************
EJECT
***************************
* *
* EQUATES *
* *
***************************
* *
* -----PRENIBL---- *
* AND POSTNIBL *
* *
***************************
BUF EQU $3E TWO BYTE POINTER.
*
* POINTS TO 256-BYTE
* USER BUFFER ANYWHERE
* IN MEMORY. PRENIBL
* CONVERTS USER DATA
* (IN BUF) INTO 5-BIT
* NIBLS 000ABCDE IN
* NBUF1 THROUGH NBUF8
* PRIOR TO 'WRITE'.
* POSTNIBL CONVERTS
* 5-BIT NIBLS ABCDE000
* BACK TO USER DATA
* (IN BUF) AFTER 'READ'.
*
NBUF1 EQU $BB00
NBUF2 EQU $BB33 OBSERVE THESE
NBUF3 EQU $BB66 PLACEMENTS
NBUF4 EQU $BB99 RELATIVE TO
NBUF5 EQU $BBCC PAGE STARTS!
NBUF6 EQU $BC00
NBUF7 EQU $BC33
NBUF8 EQU $BC66 (TO $BC99)
*
T0 EQU $26 TEMPS USED BY PRENIBL
T1 EQU $27 AND POSTNIBL.
T2 EQU $2A TEMP USED BY PRENIBL.
*
************************
* *
* ----READADR---- *
* *
************************
COUNT EQU $26 'MUST FIND' COUNT.
LAST EQU $26 'ODD BIT' NIBLS.
CSUM EQU $27 CHECKSUM BYTE.
CSSTV EQU $2C FOUR BYTES,
* CHECKSUM, SECTOR, TRACK, AND VOLUME.
*
************************
* *
* ----WRITE---- *
* *
* USES ALL NBUFS *
* AND 32-BYTE *
* DATA TABLE 'NIBL' *
* *
************************
WTEMP EQU $26 TEMP FOR DATA AT NBUF6,0.
SLOTZ EQU $27 SLOTNUM IN Z-PAG LOC.
SLOTABS EQU $678 SLOTNUM IN NON-ZPAG LOC.
*
************************
* *
* -----READ---- *
* *
* USES ALL NBUFS *
* USES LAST 54 BYTES *
* OF A CODE PAGE FOR *
* USED BYTES OF DNIBL *
* TABLE. *
* *
************************
IDX EQU $26 INDEX INTO (BUF).
DNIBL EQU $BA00 7-BIT TO 5-BIT NIBLS.
*
************************
* *
* ---- SEEK ---- *
* *
************************
TRKCNT EQU $26 HALFTRKS MOVED COUNT.
PRIOR EQU $27 PRIOR HALFTRACK.
TRKN EQU $2A DESIRED TRACK.
SLOTTEMP EQU $2B SLOT NUM TIMES $10.
CURTRK EQU $478 CURRENT TRACK ON ENTYR.
*
************************
* *
* ---- MSWAIT ---- *
* *
************************
MONTIMEL EQU $46
MONTIMEH EQU $47
*
************************
* *
* DEVICE ADDRESS *
* ASSIGNMENTS *
* *
************************
PHASEOFF EQU $C080 STEPPER PHASE OFF.
PHASEON EQU $C081 STEPPER PHASE ON.
Q6L EQU $C08C Q7L,Q6L=READ
Q6H EQU $C08D Q7L,Q6H=SENSE WPROT
Q7L EQU $C08E Q7H,Q6L=WRITE
Q7H EQU $C08F Q7H,Q6H=WRITE STORE
EJECT
****************************
* *
* PRENIBLIZE SUBR *
* *
****************************
* *
* CONVERTS 256 BYTES OF *
* USER DATA IN (BUF),0 *
* TO (BUF),255 INTO 410 *
* 5-BIT NIBLS (000ABCDE) *
* IN NBUF1 THROUGH NBUF8. *
* *
* ---- ON ENTRY ---- *
* *
* BUF IS 2-BYTE POINTER *
* TO 256 BYTES OF USER *
* DATA. *
* *
* ---- ON EXIT ----- *
* *
* A-REG: UNCERTAIN. *
* X-REG: UNCERTAIN. *
* Y-REG: HOLDS $FF. *
* CARRY: UNCERTAIN. *
* *
* NBUF1 THROUGH NBUF8 *
* CONTAIN 5-BIT NIBLS *
* OF FORM 000ABCDE. *
* *
* TEMPS T0, T1, T2 USED. *
* *
****************************
ORG $B800
OBJ $B800
PRENIBL LDX #$32 INDEX FOR (51) 5-BYTE PASSES.
LDY #$0 USER BUF INDEX.
PNIB1 LDA (BUF),Y FIRST OF 5 USER BYTES.
STA T0 (ONLY 3 LSB'S USED)
LSR
LSR ;5 MSB'S TO LOW BITS.
LSR
STA NBUF1,X FIRST OF 8 5-BIT NIBLS.
INY
LDA (BUF),Y SECOND OF 5 USER BYTES.
STA T1 (ONLY 3 LSB'S USED)
LSR
LSR ;5 MSB'S TO LOW BITS.
LSR
STA NBUF2,X SECOND OF 8 5-BIT NIBLS.
INY
LDA (BUF),Y THIRD OF 5 USER BYTES.
STA T2 (ONLY 3 LSB'S USED)
LSR
LSR ;5 MSB'S TO LOW BITS.
LSR
STA NBUF3,X THIRD OF 8 5-BIT NIBLS.
INY
LDA (BUF),Y FOURTH OF 5 USER BYTES.
LSR
ROL T2 LSB INTO T2.
LSR
ROL T1 NEXT LSB INTO T1.
LSR
ROL T0 NEXT LSB INTO T0.
STA NBUF4,X FOURTH OF 8 5-BIT NIBLS.
INY
LDA (BUF),Y FIFTH OF 5 USER BYTES.
LSR
ROL T2 LSB INTO T2.
LSR
ROL T1 NEXT LSB INTO T1.
LSR
STA NBUF5,X FIFTH OF 8 5-BIT NIBLS.
LDA T0
ROL ;NEXT LSB.
AND #$1F TRUNCATE TO 5 BITS.
STA NBUF6,X SIXTH OF 8 5-BIT NIBLS.
LDA T1
AND #$1F TRUNCATE TO 5 BITS.
STA NBUF7,X SEVENTH OF 8 5-BIT NIBLS.
LDA T2
AND #$1F TRUNCATE TO 5 BITS.
STA NBUF8,X EIGHTH OF 8 5-BIT NIBLS.
INY
DEX NEXT OF (51) 5-BYTE PASSES.
BPL PNIB1
LDA (BUF),Y
TAX
AND #$7 3 LSB'S OF LAST
STA NBUF8+$33 USER BYTE.
TXA
LSR
LSR
LSR ;5 MSB'S OF LAST
STA NBUF5+$33 USER BYTE.
RTS
EJECT
************************
* *
* WRITE SUBR *
* *
************************
* *
* WRITES DATA FROM *
* NBUF1 TO NBUF8 *
* CONVERTING 5-BIT *
* TO 7-BIT NIBLS *
* VIA 'NIBL' TABLE. :
* *
* FIRST, NBUF6 TO *
* NBUF8, HIGH TO LOW *
* THEN, NBUF1 TO *
* NBUF5, LOW TO HIGH *
* *
* ---- ON ENTRY ---- *
* *
* X-REG: SLOTNUM *
* TIMES $10. *
* *
* NBUF1 TO NBUF8 *
* HOLD NIBLS FROM *
* PRENIBL SUBR. *
* (000ABCDE) *
* *
* ---- ON EXIT ----- *
* *
* CARRY SET IF ERROR. *
* (W PROT VIOLATION) *
* *
* IF NO ERROR: *
* *
* A-REG: UNCERTAIN. *
* X-REG: UNCHANGED. *
* Y-REG: HOLDS $00. *
* CARRY CLEAR. *
* *
* SLOTABS, SLOTZ, *
* AND WTEMP USED. *
* *
* ---- ASSUMES ---- *
* *
* 1 USEC CYCLE TIME *
* *
************************
WRITE SEC ANTICIPATE WPROT ERR.
LDA Q6H,X
LDA Q7L,X SENSE WPROT FLAG.
BMI WEXIT IF HIGH, THEN ERR.
STX SLOTZ FOR ZERO PAGE ACCESS.
STX SLOTABS FOR NON-ZERO PAGE.
LDA NBUF6
STA WTEMP FOR ZERO-PAGE ACCESS.
LDA #$FF SYNC DATA.
STA Q7H,X (5) WRITE 1ST NIBL.
ORA Q6L,X (4)
PHA (3)
PLA (4) CRITICAL TIMING!
NOP (2)
LDY #$A (2) FOR 11 NIBLS.
WSYNC ORA WTEMP (3) FOR TIMING.
JSR WNIBL7 (13,9,6) WRITE SYNC.
DEY (2)
BNE WSYNC (2*) MUST NOT CROSS PAGE!
LDA #$D5 (2) 1ST DATA MARK.
JSR WNIBL9 (15,9,6)
LDA #$AA (2) 2ND DATA MARK.
JSR WNIBL9 (15,9,6)
LDA #$AD (2) 3RD DATA MARK.
JSR WNIBL9 (15,9,6)
TYA (2) CLEAR CHKSUM.
LDY #$9A (2) NBUF6-8 INDEX.
BNE WDATA1 (3) ALWAYS. NO PAGE CROSS!!
WDATA0 LDA NBUF6,Y (4) PRIOR 5-BIT NIBL.
WDATA1 EOR NBUF6-1,Y (5) XOR WITH CURRENT.
* (NBUF6 MUST BE ON PAGE BOUNDARY FOR TIMING!!)
TAX (2) INDEX TO 7-BIT NIBL.
LDA NIBL,X (4) MUST NOT CROSS PAGE!
LDX SLOTZ (3) CRITICAL TIMING!
STA Q6H,X (5) WRITE NIBL.
LDA Q6L,X (4)
DEY (2) NEXT NIBL.
BNE WDATA0 (2*) MUST NOT CROSS PAGE!
LDA WTEMP (3) PRIOR NIBL FROM BUF6.
NOP (2) CRITICAL TIMING.
WDATA2 EOR NBUF1,Y (4) XOR NBUF1 NIBL.
TAX (2) INDEX TO 7-BIT NIBL.
LDA NIBL,X (4)
LDX SLOTABS (4) TIMING CRITICAL.
STA Q6H,X (5) WRITE NIBL.
LDA Q6L,X (4)
LDA NBUF1,Y (4) PRIOR 5-BIT NIBL.
INY (2) NEXT NBUF1 NIBL.
BNE WDATA2 (2*) MUST NOT CROSS PAGE!
TAX (2) LAST NIBL AS CHKSUM.
LDA NIBL,X (4) INDEX TO 7-BIT NIBL.
LDX SLOTZ (3)
JSR WNIBL (6,9,6) WRITE CHKSUM.
LDA #$DE (2) DM4, BIT SLIP MARK.
JSR WNIBL9 (15,9,6) WRITE IT.
LDA #$AA (2) DM5, BIT SLIP MARK.
JSR WNIBL9 (15,9,6) WRITE IT.
LDA #$EB (2) DM6, BIT SLIP MARK.
JSR WNIBL9 (15,9,6) WRITE IT.
LDA Q7L,X OUT OF WRITE MODE.
WEXIT LDA Q6L,X TO READ MODE.
RTS RETURN FROM WRITE.
*****************************
* *
* 7-BIT NIBL WRITE SUBRS *
* *
* A-REG OR'D PRIOR EXIT *
* CARRY CLEARED *
* *
*****************************
WNIBL9 CLC (2) 9 CYCLES, THEN WRITE.
WNIBL7 PHA (3) 7 CYCLES, THEN WRITE.
PLA (4)
WNIBL STA Q6H,X (5) NIBL WRITE SUB.
ORA Q6L,X (4) CLOBBERS ACC, NOT CARRY.
RTS
EJECT
**************************
* *
* READ SUBROUTINE *
* *
**************************
* *
* READS 5-BIT NIBLS *
* (ABCDE000) INTO *
* NBUF1 THROUGH NBUF8 *
* CONVERTING 7-BIT *
* NIBLS TO 5-BIT *
* VIA 'DNIBL' TABLE *
* *
* FIRST READS NBUF6 TO *
* NBUF8 HIGH TO LOW, *
* THEN READS NBUF1 TO *
* NBUF5 LOW TO HIGH *
* *
* ---- ON ENTRY ---- *
* *
* X-REG: SLOTNUM *
* TIMES $10. *
* *
* READ MODE (Q6L, Q7L) *
* *
* ---- ON EXIT ----- *
* *
* CARRY SET IF ERROR. *
* *
* IF NO ERROR: *
* A-REG: HOLDS $AA *
* X-REG: UNCHANGED. *
* Y-REG: HOLDS $00 *
* CARRY CLEAR. *
* *
* NBUF1 TO NBUF8 *
* HOLD 5-BIT *
* NIBLS ABCDE000. *
* *
* USES TEMP 'IDX'. *
* *
* ---- CAUTION ----- *
* *
* OBSERVE *
* 'NO PAGE CROSS' *
* WARNINGS ON *
* SOME BRANCHES!! *
* *
* ---- ASSUMES ---- *
* *
* 1 USEC CYCLE TIME *
* *
**************************
READ LDY #$20 'MUST FIND' COUNT.
RSYNC DEY IF CAN'T FIND MARKS
BEQ RDERR ;THEN EXIT WITH CARRY SET.
RD1 LDA Q6L,X READ NIBL.
BPL RD1 *** NO PAGE CROSS! ***
RSYNC1 EOR #$D5 DATA MARK 1?
BNE RSYNC LOOP IF NOT.
NOP DELAY BETWEEN NIBLS.
RD2 LDA Q6L,X
BPL RD2 *** NO PAGE CROSS! ***
CMP #$AA DATA MARK 2?
BNE RSYNC1 (IF NOT, IS IT DM1?)
LDY #$9A INIT NBUF6 INDEX.
* (ADDED NIBL DELAY)
RD3 LDA Q6L,X
BPL RD3 *** NO PAGE CROSS! ***
CMP #$AD DATA MARK 3?
BNE RSYNC1 (IF NOT, IS IT DM1?)
* (CARRY SET IF DM3!)
LDA #$00 INIT CHECKSUM.
RDATA1 DEY
STY IDX
RD4 LDY Q6L,X
BPL RD4 *** NO PAGE CROSS! ***
EOR DNIBL,Y XOR 5-BIT NIBL.
LDY IDX
STA NBUF6,Y STORE IN NBUF6 PAGE.
BNE RDATA1 TAKEN IF Y-REG NONZERO.
RDATA2 STY IDX
RD5 LDY Q6L,X
BPL RD5 *** NO PAGE CROSS! ***
EOR DNIBL,Y XOR 5-BIT NIBL.
LDY IDX
STA NBUF1,Y STORE IN NBUF1 PAGE.
INY
BNE RDATA2
RD6 LDY Q6L,X READ 7-BIT CSUM NIBL.
BPL RD6 *** NO PAGE CROSS! ***
CMP DNIBL,Y IF LAST NBUF1 NIBL NOT
BNE RDERR EQUAL CHKSUM NIBL THEN ERR.
RD7 LDA Q6L,X
BPL RD7 *** NO PAGE CROSS! ***
CMP #$DE FIRST BIT SLIP MARK?
BNE RDERR (ERR IF NOT)
NOP DELAY BETWEEN NIBLS.
RD8 LDA Q6L,X
BPL RD8 *** NO PAGE CROSS! ***
CMP #$AA SECOND BIT SLIP MARK?
BEQ RDEXIT (DONE IF IT IS)
RDERR SEC ;INDICATE 'ERROR EXIT'.
RTS RETURN FROM READ OR READADR.
EJECT
****************************
* *
* READ ADDRESS FIELD *
* *
* SUBROUTINE *
* *
****************************
* *
* READS VOLUME, TRACK *
* AND SECTOR *
* *
* ---- ON ENTRY ---- *
* *
* XREG: SLOTNUM TIMES $10 *
* *
* READ MODE (Q6L, Q7L) *
* *
* ---- ON EXIT ----- *
* *
* CARRY SET IF ERROR. *
* *
* IF NO ERROR: *
* A-REG: HOLDS $AA. *
* Y-REG: HOLDS $00. *
* X-REG: UNCHANGED. *
* CARRY CLEAR. *
* *
* CSSTV HOLDS CHKSUM, *
* SECTOR, TRACK, AND *
* VOLUME READ. *
* *
* USES TEMPS COUNT, *
* LAST, CSUM, AND *
* 4 BYTES AT CSSTV. *
* *
* ---- EXPECTS ---- *
* *
* NORMAL DENSITY NIBLS *
* (4-BIT), ODD BITS, *
* THEN EVEN. *
* *
* ---- CAUTION ---- *
* *
* OBSERVE *
* 'NO PAGE CROSS' *
* WARNINGS ON *
* SOME BRANCHES!! *
* *
* ---- ASSUMES ---- *
* *
* 1 USEC CYCLE TIME *
* *
****************************
RDADR LDY #$F8
STY COUNT 'MUST FIND' COUNT.
RDASYN INY
BNE RDA1 LOW ORDER OF COUNT.
INC COUNT (2K NIBLS TO FIND
BEQ RDERR ADR MARK, ELSE ERR)
RDA1 LDA Q6L,X READ NIBL.
BPL RDA1 *** NO PAGE CROSS! ***
RDASN1 CMP #$D5 ADR MARK 1?
BNE RDASYN (LOOP IF NOT)
NOP ADDED NIBL DELAY.
RDA2 LDA Q6L,X
BPL RDA2 *** NO PAGE CROSS! ***
CMP #$AA ADR MARK 2?
BNE RDASN1 (IF NOT, IS IT AM1?)
LDY #$3 INDEX FOR 4-BYTE READ.
* (ADDED NIBL DELAY)
RDA3 LDA Q6L,X
BPL RDA3 *** NO PAGE CROSS! ***
CMP #$B5 ADR MARK 3?
BNE RDASN1 (IF NOT, IS IT AM1?)
* (LEAVES CARRY SET!)
LDA #$0 INIT CHECKSUM.
RDAFLD STA CSUM
RDA4 LDA Q6L,X READ 'ODD BIT' NIBL.
BPL RDA4 *** NO PAGE CROSS! ***
ROL ;ALIGN ODD BITS, '1' INTO LSB.
STA LAST (SAVE THEM)
RDA5 LDA Q6L,X READ 'EVEN BIT' NIBL.
BPL RDA5 *** NO PAGE CROSS! ***
AND LAST MERGE ODD AND EVEN BITS.
STA CSSTV,Y STORE DATA BYTE.
EOR CSUM XOR CHECKSUM.
DEY
BPL RDAFLD LOOP ON 4 DATA BYTES.
TAY IF FINAL CHECKSUM
BNE RDERR NONZERO, THEN ERROR.
RDA6 LDA Q6L,X FIRST BIT-SLIP NIBL.
BPL RDA6 *** NO PAGE CROSS! ***
CMP #$DE
BNE RDERR ERROR IF NONMATCH.
NOP DELAY BETWEEN NIBLS.
RDA7 LDA Q6L,X SECOND BIT-SLIP NIBL.
BPL RDA7 *** NO PAGE CROSS! ***
CMP #$AA
BNE RDERR ERROR IF NONMATCH.
RDEXIT CLC CLEAR CARRY ON
RTS NORMAL READ EXITS.
EJECT
***************************
* *
* POSTNIBLIZE SUBR *
* *
***************************
* *
* CONVERTS 5-BIT NIBLS *
* OF FORM ABCDE000 IN *
* NBUF1 THROUGH NBUF8 *
* INTO 256 BYTES OF *
* USER DATA IN BUF. *
* *
* ---- ON ENTRY ---- *
* *
* X-REG: HOLDS SLOTNUM *
* TIMES $10. *
* *
* BUF IS 2-BYTE POINTER *
* TO 256 BYTES OF USER *
* DATA TO BE CONVERTED *
* TO 5-BIT NIBLS IN *
* NBUF1 THROUGH NBUF8 *
* PRIOR TO WRITE. *
* *
* ---- ON EXIT ----- *
* *
* A-REG: UNCERTAIN. *
* Y-REG: HOLDS $FF. *
* X-REG: HOLDS $FF. *
* CARRY: UNCERTAIN. *
* *
* 5-BIT NIBLS OF FORM *
* 000ABCDE IN 410 *
* BYTES FROM NBUF1 *
* TO NBUF8. *
* *
***************************
POSTNIB LDX #$32 INDEX FOR 51 PASSES.
LDY #$0 INDEX TO USER BUF.
POSTNB1 LDA NBUF6,X
LSR
LSR
LSR
STA T1
LSR
STA T0
LSR
ORA NBUF1,X
STA (BUF),Y FIRST OF 5 USER BYTES.
INY
LDA NBUF7,X
LSR
LSR
LSR
LSR
ROL T1
LSR
ROL T0
ORA NBUF2,X
STA (BUF),Y SECOND OF 5 USER BYTES.
INY
LDA NBUF8,X
LSR
LSR
LSR
LSR
ROL T1
LSR
ROL T0
ORA NBUF3,X
STA (BUF),Y THIRD OF 5 USER BYTES.
INY
LDA T0
AND #$7
ORA NBUF4,X
STA (BUF),Y FOURTH OF 5 USER BYTES.
INY
LDA T1
AND #$7
ORA NBUF5,X
STA (BUF),Y FIFTH OF 5 USER BYTES.
INY
DEX NEXT OF 51 PASSES.
BPL POSTNB1 HANDLE LAST USER
LDA NBUF8+$33 BYTE DIFFERENTLY.
LSR
LSR
LSR
ORA NBUF5+$33
STA (BUF),Y
RTS
EJECT
**************************
* *
* FAST SEEK SUBROUTINE *
* *
**************************
* *
* ---- ON ENTRY ---- *
* *
* X-REG HOLDS SLOTNUM *
* TIMES $10. *
* *
* A-REG HOLDS DESIRED *
* HALFTRACK. *
* (SINGLE PHASE) *
* *
* CURTRK HOLDS CURRENT *
* HALFTRACK. *
* *
* ---- ON EXIT ----- *
* *
* A-REG UNCERTAIN. *
* Y-REG UNCERTAIN. *
* X-REG UNDISTURBED. *
* *
* CURTRK AND TRKN HOLD *
* FINAL HALFTRACK. *
* *
* PRIOR HOLDS PRIOR *
* HALFTRACK IF SEEK *
* WAS REQUIRED. *
* *
* MONTIMEL AND MONTIMEH *
* ARE INCREMENTED BY *
* THE NUMBER OF *
* 100 USEC QUANTUMS *
* REQUIRED BY SEEK *
* FOR MOTOR ON TIME *
* OVERLAP. *
* *
* --- VARIABLES USED --- *
* *
* CURTRK, TRKN, COUNT, *
* PRIOR, SLOTTEMP *
* MONTIMEL, MONTIMEH *
* *
**************************
SEEK STA TRKN TARGET TRACK.
CMP CURTRK ON DESIRED TRACK?
BEQ SEEKXIT YES, HIT IT AND RETURN.
STX SLOTTEMP SAVE X-REG.
LDA #$0
STA TRKCNT HALFTRACK COUNT.
SEEK2 LDA CURTRK SAVE CURTRK FOR
STA PRIOR DELAYED TURNOFF.
SEC
SBC TRKN DELTA-TRACKS.
BEQ SEEKEND DONE, FINISH SEEK.
BCS OUT (MOVE OUT, NOT IN)
EOR #$FF CALC TRKS TO GO.
INC CURTRK INCR CURRENT TRACK (IN).
BCC MINTST (ALWAYS TAKEN)
OUT ADC #$FE CALC TRKS TO GO.
DEC CURTRK DECR CURRENT TRACK (OUT).
MINTST CMP TRKCNT
BCC MAXTST AND 'TRKS MOVED'.
LDA TRKCNT
MAXTST CMP #$C
BCC STEP IF > $B, USE $B.
LDA #$B
STEP TAY ACCELLERATION INDEX.
LDA CURTRK
AND #$3 INDEX TO 'CURRENT
ASL ; PHASE' OF 4-PHASE
ORA SLOTTEMP STEPPER.
TAX
LDA PHASEON,X HIT NEXT PHASE
LDA ONTABLE,Y FOR 'ONTIME'.
JSR MSWAIT (100 USEC INTERVALS)
LDA PRIOR
AND #$3 INDEX TO 'PRIOR PHASE'
ASL ; OF 4-PHASE STEPPER.
ORA SLOTTEMP
TAX
LDA PHASEOFF,X PRIOR PHASE OFF,
LDA OFFTABLE,Y THEN WAIT 'OFFTIME'.
JSR MSWAIT (100 USEC INTERVALS)
INC TRKCNT 'TRACKS MOVED' COUNT.
BNE SEEK2 (ALWAYS TAKEN)
SEEKEND LDA #$5F DELAY 9.5 MSEC FOR
JSR MSWAIT SETTLING TIME.
LDX SLOTTEMP RESTORE X-REG.
SEEKXIT RTS RETURN.
EJECT
**************************
* *
* MSWAIT SUBROUTINE *
* *
**************************
* *
* DELAYS A SPECIFIED *
* NUMBER OF 100 USEC *
* INTERVALS FOR MOTOR *
* ON TIMING. *
* *
* ---- ON ENTRY ---- *
* *
* A-REG: HOLDS NUMBER *
* OF 100 USEC *
* INTERVALS TO *
* DELAY. *
* *
* ---- ON EXIT ----- *
* *
* A-REG: HOLDS $00. *
* X-REG: HOLDS $00. *
* Y-REG: UNCHANGED. *
* CARRY: SET. *
* *
* MONTIMEL, MONTIMEH *
* ARE INCREMENTED ONCE *
* PER 100 USEC INTERVAL*
* FOR MOTON ON TIMING. *
* *
* ---- ASSUMES ---- *
* *
* 1 USEC CYCLE TIME *
* *
**************************
MSWAIT LDX #$11
MSW1 DEX DELAY 86 USEC.
BNE MSW1
INC MONTIMEL
BNE MSW2 DOUBLE-BYTE
INC MONTIMEH INCREMENT.
MSW2 SEC
SBC #$1 DONE 'N' INTERVALS?
BNE MSWAIT (A-REG COUNTS)
RTS
EJECT
**************************
* *
* PHASE ON-, OFF-TIME *
* TABLES IN 100-USEC *
* INTERVALS. (SEEK) *
* *
**************************
ONTABLE HEX 013028
HEX 24201E
HEX 1D1C1C
HEX 1C1C1C
OFFTABLE HEX 702C26
HEX 221F1E
HEX 1D1C1C
HEX 1C1C1C
EJECT
**************************
* *
* 7-BIT TO 5-BIT *
* 'DENIBLIZE' TABL *
* *
* VALID CODES *
* $AB TO $FF ONLY. *
* ($DA NOT VALID) *
* *
* ---- CAUTION ---- *
* *
* INSURE THAT FOLLOWING *
* 'RE-ORG' IS OK. *
* *
**************************
ORG $BAAB
OBJ $BAAB
HEX 000108
HEX 101802
HEX 030405
HEX 062028
HEX 300709
HEX 38400A
HEX 485058
HEX 0B0C0D
HEX 0E0F11
HEX 121314
HEX 151617
HEX 191A1B
HEX 1C1D1E
HEX 212223
HEX 246068
HEX 252670
HEX 782780
HEX 889029
HEX 2A2B2C
HEX 2D2E2F
HEX 313233
HEX 98A034
HEX A8B0B8
HEX 353637
HEX 393AC0
HEX C8D03B
HEX 3CD8E0
HEX 3EE8F0
HEX F8
EJECT
**************************
* *
* 5-BIT TO 7-BIT *
* NIBL CONVERSION *
* TABLE *
* *
**************************
* *
* CODES $AA, $D5 *
* NOT USED *
* *
**************************
ORG $BC9A
OBJ $BC9A
NIBL HEX ABADAE
HEX AFB5B6
HEX B7BABB
HEX BDBEBF
HEX D6D7DA
HEX DBDDDE
HEX DFEAEB
HEX EDEEEF
HEX F5F6F7
HEX FAFBFD
HEX FEFF
HEX 1C1C1C
END
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