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;********************************************************* ; ; ╞AST SERIAL ┬╒╙ ROUTINES FOR 1541/71 ; ; ╫RITTEN ┬Y ╥OBERT ┴. ╙TOERRLE (A.K.A. ═┴╠┴╦┴╔) ; ; ┴UGUST 29, 1988 ; ; ╨OWER ┴SSEMBLER FORMAT ; ;********************************************************** ; ;╘HIS PACKAGE IS INTENDED TO INSTRUCT PROGRAMMERS WITH A ;REASONABLE PROFICIENCY IN ASSEMBLY LANGUAGE IN THE ;IMPLEMENTATION OF FAST SERIAL COMMUNICATION ROUTINES FOR ;THE 1571/41. ╘HE AUTHOR DOES NOT CLAIM THAT THESE ARE THE ;FASTEST TECHNIQUES. ; ;╨LEASE NOTE THAT THE ROUTINES PROVIDED DO NOT CONSTITUTE ;A COMPLETE DISK OPERATING SYSTEM BUT PROVIDE ONLY A MEANS ;FOR ACCESSING SPECIFIC TRACKS AND SECTORS ON THE DISK. ;╘HE ROUTINES CAN BE EASILY ACTIVATED AND DEACTIVATED AT ;WILL AND DO NOT AFFECT OTHER DEVICES ON THE SERIAL BUS. ; ;┬EST SPEED RESULTS ARE OBTAINED WHEN THE TEXT SCREEN IS ;BLANKED DURING FAST DATA TRANSFERS, AND THESE ROUTINES ARE ;SET UP TO BLANK THE SCREEN WHENEVER A DRIVE'S FAST ROUTINE ;IS ACTIVE. ┘OU WILL FIND NOTES WHERE APPROPRIATE ON ;CONFIGURING THE ROUTINES TO WORK WITH THE SCREEN ON. ; ;---------------------------------------------------------- ;╙TANDARD ╦ERNAL ROUTINE EQUATES ;---------------------------------------------------------- ; SETLFS = $FFBA SETNAM = $FFBD OPEN = $FFC0 CLOSE = $FFC3 CHKIN = $FFC6 CHKOUT = $FFC9 CLRCHN = $FFCC CHRIN = $FFCF CHROUT = $FFD2 ; ;---------------------------------------------------------- ;├ONSTANTS ;---------------------------------------------------------- ; DRIVESTART = $0500 ;╫HERE ═╠ WILL RESIDE IN DRIVE ; ╔F THIS IS CHANGED, THE ╒X COMMAND ; IN ┴├╘╔╓┴╘┼╞ MUST ALSO BE CHANGED! CIA = $DD00 ;├OMPUTER INTERFACE TO SERIAL BUS ; ;---------------------------------------------------------- ;╙TORAGE USED BY THIS PROGRAM ;---------------------------------------------------------- ; STORAGE = $C800 ;╙TART OF EXTERNAL STORAGE FASTBUF = STORAGE ;╚OLDS BLOCK RECEIVED/TO BE SENT VAR = STORAGE+256 ;╙TART OF EXTERNAL VARIABLES FTRACK = VAR ;├URRENT TRACK FSECTOR = VAR+1 ;├URRENT SECTOR BLOCKCNT = VAR+2 ;╬UMBER OF 32 BYTE CHUNKS TO SEND ; ;---------------------------------------------------------- ;┌ERO-PAGE STORAGE USED BY THIS PROGRAM ;---------------------------------------------------------- ; APTR = $FB ;╨OINTS INTO DRIVE CODE IN 64 BPTR = $FD ;╨OINTS INTO DRIVE ╥┴═ BVALUE = $FB ;┬YTE RECEIVED FROM DRIVE. ═╒╙╘ BE ;┌╨ FOR TIMING PURPOSES! ; ;---------------------------------------------------------- ;╨ROGRAM START ADDRESS AND JUMP TABLE TO MAJOR ROUTINES ;---------------------------------------------------------- ; .ORG $C000 ;╨ROGRAM START ADDRESS. ═AY BE ; RELOCATED AT WILL ; JMP PREPAREF ;╙END ═╠ ROUTINES TO DRIVE JMP ACTIVATEF ;┴CTIVATE FAST ROUTINES IN DRIVE JMP RELEASEF ;─EACTIVATE FAST ROUTINES JMP READF ;╥EAD A BLOCK FROM DRIVE JMP WRITEF ;╫RITE A BLOCK TO DRIVE JMP GETF ;╟ET A BYTE FROM DRIVE JMP SENDF ;╙END A BYTE TO DRIVE ; ;---------------------------------------------------------- ;├OMPUTER-RESIDENT ROUTINES ;---------------------------------------------------------- ; ;╨╥┼╨┴╥┼╞ SENDS ═╠ ROUTINES TO THE DRIVE TO ACCOMPLISH THE ;FAST SERIAL BUS TRANSFERS, BUT DOES NOT ACTIVATE THE ;ROUTINES. ╘HAT ALLOWS SEVERAL DRIVES TO BE ACCESSED USING ;THE FAST ROUTINES BY INITIALIZING THEM EACH USING THIS ;ROUTINE. ; ;┬┼╞╧╥┼ ├┴╠╠╔╬╟: .┴ SHOULD CONTAIN DEVICE NUMBER (8-11) ; OF DRIVE BEING INITIALIZED. ; ;╘HE STANDARD ═-╫ COMMAND IS USED TO SEND THE CODE TO ;THE DRIVE IN 32 BYTE CHUNKS. ╘HE CORRECT AMOUNT OF CODE ;WILL BE SENT REGARDLESS OF WHETHER THE LENGTH OF THE ;DRIVE CODE IS CHANGED, SO FEEL FREE TO MAKE ADDITIONS/ ;DELETIONS TO THE DRIVE PORTION OF THIS SOURCE. ╨LEASE ;NOTE THAT THIS ROUTINE DOES NOT PRESERVE ANY REGISTERS. ; PREPAREF = * ; TAX LDA #7 LDY #15 JSR SETLFS LDA #0 JSR SETNAM JSR OPEN ;╧PEN AN ERROR CHANNEL TO DEVICE ; LDA #<DRIVECODE ;╙ET UP ┴╨╘╥ TO POINT TO DRIVE STA APTR ; CODE IN COMPUTER (APPENDED TO LDA #>DRIVECODE ; THE END OF THIS FILE) STA APTR+1 LDA #<DRIVESTART ;┬╨╘╥ WILL POINT TO CORRESPONDING STA BPTR ; ADDRESS IN DRIVE ╥┴═ LDA #>DRIVESTART STA BPTR+1 LDA #ENDDRIVECODE-DRIVECODE/32+1 STA BLOCKCNT ;╬UMBER OF 32 BYTE CHUNKS TO SEND ; PRP1 LDX #7 ;╙END AN ═-╫ COMMAND TO DRIVE JSR CHKOUT LDA #"M" JSR CHROUT LDA #"-" JSR CHROUT LDA #"W" JSR CHROUT LDA BPTR ;╙END ADDRESS IN DRIVE ╥┴═ JSR CHROUT LDA BPTR+1 JSR CHROUT LDA #32 ;╬UMBER OF BYTES TO BE SENT JSR CHROUT LDY #0 - LDA (APTR),Y JSR CHROUT ;╙END 32 BYTES TO DRIVE INY CPY #32 BNE - LDA APTR ;╙ET UP POINTERS FOR NEXT CLC ; 32 BYTE CHUNK ADC #32 STA APTR BCC + INC APTR+1 + LDA BPTR CLC ADC #32 STA BPTR BCC + INC BPTR+1 + JSR CLRCHN ; DEC BLOCKCNT ;═ORE CHUNKS TO SEND? BNE PRP1 ; ┘ES - GO BACK AND SEND ANOTHER ; JSR CLRCHN ; ╬O - ├LOSE FILE AND EXIT LDA #7 JSR CLOSE RTS ; ;┴├╘╔╓┴╘┼╞ IS USED TO ACTIVATE THE FAST SERIAL ROUTINES IN ;A DRIVE. ╨╥┼╨┴╥┼╞ MUST ALREADY HAVE BEEN CALLED FOR THE ;DRIVE, OR THE DRIVE WILL LIKELY CRASH! ╘HE SERIAL BUS WILL ;BE SEIZED BY THE DRIVE, SO WHILE FAST ROUTINES ARE ACTIVE ;IN ANY DRIVE, ╬╧ OTHER DRIVE OR SERIAL PERIPHERAL MAY BE ;USED. ═ULTI-DRIVE OPERATIONS ARE EASILY ACCOMPLISHED BY ;REPEATEDLY USING ┴├╘╔╓┴╘┼╞ AND ╥┼╠┼┴╙┼╞ FOR EACH DRIVE ;EACH TIME IT IS ACCESSED. ╬OTE THAT WHEN THE FAST SERIAL ;ROUTINES ARE NOT ACTIVE IN A DRIVE, NORMAL ─╧╙ COMMANDS ;MAY BE SENT TO THAT DRIVE. ╚OWEVER, KEEP IN MIND THAT ;THE DRIVE CODE (KEPT IN BUFFER 2 @ $500) MIGHT BE ;OVERWRITTEN, AND THUS ╨╥┼╨┴╥┼╞ SHOULD BE CALLED AGAIN ;FOR THAT DRIVE BEFORE ANY FURTHER FAST COMMUNICATION. ; ;┬┼╞╧╥┼ ├┴╠╠╔╬╟ ╘╚╔╙ ╥╧╒╘╔╬┼: .┴ = ─EVICE NUMBER (8-11) ;╧╬ ╥┼╘╒╥╬: ╬O REGISTERS ARE PRESERVED! ; ACTIVATEF = * ; TAX LDA #7 LDY #15 JSR SETLFS LDA #0 JSR SETNAM JSR OPEN ;╧PEN AN ERROR CHANNEL TO DRIVE ; LDA $D011 ;╘HESE THREE LINES BLANK THE SCREEN AND #239 ; AND MAY BE REMOVED IF YOU DO NOT STA $D011 ; WANT SCREEN BLANKING ; LDX #7 ;╙END A ╒├ COMMAND TO THE DRIVE, JSR CHKOUT ; WHICH TELLS THE DRIVE TO BEGIN LDA #"U" ; EXECUTING CODE AT $500, WHICH JSR CHROUT ; IS WHERE THE FAST ROUTINE RESIDES LDA #"C" JSR CHROUT LDA #13 JSR CHROUT JSR CLRCHN LDA #%00000111 ;├OMPUTER ALLOWS ├╠╦ AND ─┴╘┴ TO STA CIA ; GO HIGH LDY #255 ;─ELAY LOOP NECESSARY TO ALLOW LDX #127 ; DRIVE CODE TO INITIALIZE ITSELF - DEX ; AND ENTER MAIN LOOP BNE - DEY BNE - RTS ; ;╘HIS ROUTINE TELLS THE DRIVE THAT IS CURRENTLY EXECUTING ;THE FAST ROUTINES TO RELEASE THE SERIAL BUS. ╘HE FAST ;ROUTINES ARE DEACTIVATED, AND THE NORMAL ─╧╙ TAKES OVER ;IN THAT DRIVE. ; ;╔T IS NOT NECESSARY TO PASS THE DRIVE NUMBER TO THIS ;ROUTINE, AS ONLY ONE SERIAL DEVICE CAN BE ACTIVE AT ;ONCE. ╬OTE: ╬O REGISTERS ARE PRESERVED. ; RELEASEF = * ; SEI LDA #0 ;╙END COMMAND 0 (DEACTIVATE) TO JSR SENDF ; CURRENT DEVICE CLI ; LDA $D011 ;╘HESE THREE LINES REACTIVATE ORA #16 ; THE TEXT SCREEN AND ARE STA $D011 ; UNNECESSARY IF NOT BLANKED ; LDA #7 ;├LOSE LOGICAL FILE TO KEEP THINGS JMP CLOSE ; TIDY FOR NORMAL ╧╙ ; ;╥┼┴─╞ READS A BLOCK FROM THE CURRENTLY ACTIVE DRIVE. ;┬EFORE CALLING THIS ROUTINE, THE TRACK (1-35) SHOULD BE ;STORED IN ╞╘╥┴├╦, AND THE SECTOR SHOULD BE STORED IN ;╞╙┼├╘╧╥. ╧N RETURN, THE DATA IN THAT BLOCK WILL BE ;IN ╞┴╙╘┬╒╞. ┴LSO, THE ACCUMULATOR WILL BE SET TO REFLECT ;THE ERROR STATUS OF THE DRIVE. ╨OSSIBLE VALUES: ; ; 0 = ╧╦ 8 = ╫RITE PROTECT ON ; 1 = ╧╦ 9 = ╫RONG HEADER CHKSUM ; 2 = ┬LOCK HEADER NOT FOUND ┴ = ─ATA BLOCK TOO LONG ; 3 = ╙YNC MARK NOT FOUND ┬ = ┬AD DISK ╔─ ; 4 = ─ATA BLOCK NOT FOUND ─ = ╔NDEX HOLE NOT FOUND ; 5 = ┬AD DATA BLOCK CHECKSUM ┼ = ├ONTROLLER ERROR ; 6 = ╞ORMAT ERROR ╞ = ╬O DISK FOUND ; 7 = ╓ERIFY ERROR ; ;╙TATUS BITS WILL BE SET TO REFLECT THE VALUE IN .┴ ;╬O REGISTERS ARE PRESERVED. ; READF = * ; SEI LDA #1 ;╙END CODE 1 (READ BLOCK) TO DRIVE JSR SENDF LDA FTRACK ;╙END TRACK/SECTOR TO DRIVE JSR SENDF LDA FSECTOR JSR SENDF LDY #0 ;╥ECEIVE 256 BYTES THAT MAKE UP - JSR GETF ; BLOCK FROM DRIVE STA FASTBUF,Y INY BNE - JSR GETF ;257TH BYTE IS A STATUS BYTE CLI ORA #0 ;╙ET STATUS FLAGS TO REFLECT .┴ RTS ; ;╫╥╔╘┼╞ SENDS THE 256 BYTES AT ╞┴╙╘┬╒╞ TO THE BLOCK WHOSE ;TRACK IS IN ╞╘╥┴├╦ AND WHOSE SECTOR IS IN ╞╙┼├╘╧╥. ╧N ;RETURN, .┴ WILL CONTAIN THE ERROR STATUS, AS DISCUSSED FOR ;THE ╥┼┴─╞ ROUTINE ABOVE. ╬O REGISTERS ARE PRESERVED. ; WRITEF = * ; SEI LDA #2 ;╙END COMMAND 2 (WRITE BLOCK) JSR SENDF LDA FTRACK ;╙END TRACK/SECTOR TO DRIVE JSR SENDF LDA FSECTOR JSR SENDF LDY #0 ;╙END 256 BYTES TO DRIVE - LDA FASTBUF,Y JSR SENDF INY BNE - JSR GETF ;╟ET ERROR STATUS FROM DRIVE CLI ORA #0 ;╙ET STATUS FLAGS TO REFLECT .┴ RTS ; ;╙┼╬─╞ SENDS A SINGLE BYTE (IN .┴) TO THE CURRENT FAST ;DRIVE. ╘HE CONVENTIAL SERIAL BUS COMMUNICATION ROUTINES ;ARE SLOW BECAUSE THEY SEND ONE BIT AT A TIME AND INCLUDE ;A LOT OF "HANDSHAKING" BETWEEN EACH BIT. ╘HESE ROUTINES ;ONLY HANDSHAKE AT THE BEGINNING OF EACH ┬┘╘┼. ╔N ADDITION ;╘╫╧ BYTES ARE SENT AT ONCE (VIA THE USE OF THE ├╠╦ LINE ;IN ADDITION TO ─┴╘┴ TO SEND BITS). ╙INCE THERE IS NO ;HANDSHAKING WHILE SENDING A BYTE, THE TIMING OF THE ;SENDING ROUTINE (IN THE COMPUTER) MUST MATCH THE TIMING ;OF THE RECEIVING ROUTINE (IN THE DRIVE) IN ORDER FOR ;A BYTE TO BE TRANSMITTED PROPERLY. ; SENDF = * ; - LDX $D012 ;╫AIT FOR ELECTRON GUN TO MOVE CPX #48 ; OFF OF VISIBLE SCREEN. ╘HESE 3 BCS - ; LINES CAN BE REMOVED IF BLANKED ; LDX #%00010111 ;┬RING ├╠╦ LINE LOW TO SIGNAL NOP ; DRIVE THAT A BYTE IS ON ITS NOP ; WAY. ╟IVE DRIVE SOME TIME (╬╧╨S) NOP ; TO ENTER RECEIVE BYTE ROUTINE NOP NOP ;╙ERIAL PORT LINES ARE FOUND AT STX CIA ; ├╔┴ LOCATION $──00 IN ├64 PHA AND #3 ;╔SOLATE BITS 0 AND 1 AND USE TAX ; TABLE TO DETERMINE PROPER VALUE LDA FTABLE,X ; TO GIVE ├╠╦ AND ─┴╘┴ EACH A BIT STA CIA LDA $FF ;3-CYCLE DELAY NOP ;╬╧╨ = 2 CYCLE DELAY PLA ;╥ETRIEVE ORIGINAL BYTE LSR ;╟ET BITS 2 AND 3 LSR PHA AND #3 ;╔SOLATE BITS AND SEND AS ├╠╦ TAX ; AND ─┴╘┴ LDA FTABLE,X STA CIA NOP PLA ;╥EPEAT PROCEDURE FOR BITS 4 AND 5 LSR LSR PHA AND #3 TAX LDA FTABLE,X STA CIA NOP PLA ;╥EPEAT PROCEDURE FOR BITS 6 AND 7 LSR LSR AND #3 TAX LDA FTABLE,X STA CIA NOP ;╠ONG DELAY WHILE DRIVE PROCESSES NOP ; LAST TWO BITS NOP NOP NOP NOP NOP NOP NOP NOP NOP LDA #%00000111 ;┬RING ├╠╦ AND ─┴╘┴ HIGH TO STA CIA ; PREPARE FOR NEXT SEND/GET RTS ; ;╥ECEIVE A BYTE FROM THE CURRENT FAST DRIVE. ╘HE BYTE ;WILL BE RETURNED IN THE ACCUMULATOR. ╬O REGISTERS ARE ;PRESERVED. ╙EE NOTES FOR ╙┼╬─╞ ABOVE. ; GETF = * ; LDA #64 ;╫AIT FOR ├╠╦ TO GO LOW, WHICH - BIT CIA ; MEANS DRIVE IS READY TO SEND BNE - ; - LDA $D012 ;╫AIT FOR ELECTRON GUN TO MORE OFF CMP #48 ;SCREEN. ╬OT NECESSARY IF BLANKING BCS - ;IS BEING USED! ; + LDA #%00100011 ;┬RING ─┴╘┴ LOW AS A SIGNAL THAT STA CIA ; COMPUTER IS READY TO RECEIVE NOP ;╠ONG DELAY WHILE DRIVE PREPARES NOP ; FIRST TWO BITS NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP LDA #%00000011 ;┴LLOW ├╠╦ AND ─┴╘┴ TO GO HIGH SO STA CIA ; DRIVE HAS CONTROL OF THEM LDX #4 ;╠OOP TO GET 4 PAIRS OF BITS - LDA CIA ;╥EAD SERIAL BUS ROL ;╥OLL TWO BITS OUT OF SERIAL BUS ROR BVALUE ; INTERFACE REGISTER INTO STORAGE ROL ; FOR CURRENT BYTE ROR BVALUE NOP LDA $FF ;3 CYCLE DELAY DEX BNE - LDA BVALUE ;╥ETURN WITH COMPLETE BYTE RTS ; ;╘ABLE FOR FAST SEND ROUTINE (COMPUTER). ╘HIS TABLE IS USED ;TO CONVERT A BIT PAIR INTO THE NECESSARY VALUE TO STORE ;AT THE SERIAL BUS COMMUNICATION REGISTER. ├╠╦ TAKES ON THE ;VALUE OF THE LEAST SIGNIFICANT BIT AND ─┴╘┴ REPRESENTS THE ;═╙┬. ; FTABLE .BYTE %00000111 ;┬IT PAIR 00 .BYTE %00010111 ;01 .BYTE %00100111 ;02 .BYTE %00110111 ;03 ; ;---------------------------------------------------------- ;╘HIS CODE WILL RESIDE IN DRIVE MEMORY ;---------------------------------------------------------- ; DRIVECODE = * ; ;╔N ORDER TO INSURE MAXIMUM COMPATIBILITY WITH VARIOUS ;1541 "CLONES," ONLY THE STANDARD MEANS OF INTERFACING WITH ;THE DRIVE CONTROLLER WAS USED, E.G. THE JOB LOOP. ╘HIS IS ;AN INTERRUPT-DRIVEN ROUTINE THAT PERFORMS THE MOST BASIC ;DRIVE FUNCTIONS (I.E. READING AND WRITING A BLOCK). ; .OFF $0500 ;┬EGIN OFFSET CODING. ; ;╓╔┴ (╓ERSATILE ╔NTERFACE ┴DAPTOR) EQUATES ; VIA1 = $1800 ;╔NTERFACE TO SERIAL BUS VIA2 = $1C00 ;CONTROLS DRIVE ELECTRONICS ; ;╩OB LOOP INTERFACE LOCATIONS. ; JOB = 0 ;╩OB TO BE EXECUTED/JOB STATUS JOBTRACK = 6 ;╘RACK FOR CURRENT JOB JOBSECTOR = 7 ;╙ECTOR FOR CURRENT JOB JOBBUFFER = $300 ;┬UFFER USED BY JOB LOOP 0 ; ;┌ERO-PAGE LOCATIONS IN DRIVE MEMORY USED FOR TEMPORARY ;STORAGE BY THESE ROUTINES. ; BYTE = 44 ;┬YTE TO SEND/BYTE RECEIVED FYTEMP = 45 ;╙TORAGE FOR ┘ REGISTER ; ;╘HIS ROUTINE INITIALIZES THE DRIVE FOR FAST COMMUNICATION. ; SEI ;╠OCK OUT NORMAL INTERRUPTS LDA VIA2 ;╘URN OFF THE DRIVE LIGHT AND #$F7 ; (COSMETIC PURPOSES ONLY) STA VIA2 LDY #127 ;╫AIT FOR COMPUTER TO GET READY LDX #63 - DEX BNE - DEY BNE - ; ;═AIN LOOP - ACCEPT THE FOLLOWING ONE-BYTE COMMAND CODES ;FROM THE COMPUTER: ; ; 0 = ╥ETURN TO NORMAL ─╧╙ 2 = ╫RITE A BLOCK ; 1 = ╥EAD A BLOCK ; ;├OMMANDS 1 AND 2 REQUIRE TWO MORE BYTES TO FOLLOW ;IMMEDIATELY: THE TRACK AND SECTOR FOR THE GIVEN OPERATION. ; LOOP = * ; JSR GET ;╫AIT FOR AND RETRIEVE COMMAND CMP #1 ; NUMBER FROM COMPUTER. ╔F NOT BNE LOOP2 ; COMMAND 1 (READ), BRANCH... ; ;├OMMAND #1: ╥EAD A BLOCK FROM SPECIFIED TRACK/SECTOR. ;╔F THERE ARE ERRORS, THE OPERATION WILL BE RETRIED SEVEN ;TIMES BEFORE AN ERROR CONDITION IS REPORTED TO THE ;COMPUTER. ; JSR GET ;╟ET TRACK STA JOBTRACK JSR GET ;╟ET SECTOR STA JOBSECTOR LDA VIA2 ;╘URN DRIVE LIGHT ON DURING READ ORA #8 ; OPERATION STA VIA2 ; (COSMETIC PURPOSES ONLY) LDA #7 ;7 ATTEMPTS BEFORE GIVING UP STA BYTE FRL LDA #$80 ;$80 = ╩OB TO READ A BLOCK STA JOB CLI ;┴LLOW INTERRUPT-DRIVEN JOB - BIT JOB ; LOOP TO FUNCTION. ╫HEN VALUE BMI - ; BECOMES POSITIVE, JOB IS SEI ; FINISHED LDA JOB ;╩╧┬ NOW CONTAINS ERROR STATUS CMP #2 ;╔F ╧╦, SEND BYTES TO COMPUTER BCC + DEC BYTE ;╧THERWISE, TRY AGAIN BNE FRL + LDA VIA2 ;╘URN DRIVE LIGHT OFF AND #$F7 ; (COSMETIC PURPOSES ONLY) STA VIA2 LDY #0 ;╙END 256 BYTES THAT MAKE UP - LDA JOBBUFFER,Y ; BLOCK TO COMPUTER JSR SEND INY BNE - LDA JOB ;╙END ERROR STATUS TO COMPUTER JSR SEND JMP LOOP ;╥ETURN TO WAIT FOR NEXT COMMAND ; ;├ONTINUATION OF MAIN LOOP: IF NOT COMMAND #2 (WRITE BLOCK) ;THEN BRANCH... ; LOOP2 CMP #2 BNE LOOP3 ; ;├OMMAND #2: ╥ECEIVE A TRACK AND SECTOR, AS WELL AS 256 ;BYTES FROM COMPUTER AND WRITE THEM TO DISK AT THE ;SPECIFIED TRACK AND SECTOR. ; DDWRITE JSR GET ;╟ET TRACK STA JOBTRACK JSR GET ;╟ET SECTOR STA JOBSECTOR LDY #0 ;╥ECEIVE 256 BYTES FROM COMPUTER - JSR GET ; AND STORE IN JOB BUFFER STA JOBBUFFER,Y INY BNE - LDA #7 ;7 ATTEMPTS BEFORE REPORTING ERROR STA BYTE FWL LDA #$90 ;$90 = ╩OB TO WRITE A SECTOR STA JOB LDA VIA2 ;╘URN ON DRIVE LIGHT ORA #8 ; (COSMETIC PURPOSES ONLY) STA VIA2 CLI ;┴LLOW INTERRUPT-DRIVEN JOB LOOP - BIT JOB ; TO FUNCTION. ╓ALUE WILL BECOME BMI - ; POSITIVE WHEN JOB IS FINISHED SEI LDA VIA2 ;╘URN OFF DRIVE LIGHT AND #$F7 ; (COSMETIC PURPOSES ONLY) STA VIA2 LDA JOB ;─ID JOB LOOP REPORT AN ERROR? CMP #2 BCC + ; ╬O - REPORT ╧╦ STATUS TO COMPUTER DEC BYTE ; ┘ES - TRY AGAIN BNE FWL + JSR SEND ;╙END ERROR STATUS TO COMPUTER JMP LOOP ;╥ETURN TO WAIT FOR NEXT COMMAND ; ;┴NY COMMAND OTHER THAN 1 OR 2 RESULTS IN TERMINATION OF ;THE FAST SERIAL ROUTINES AND RETURN TO NORMAL ─╧╙. ; LOOP3 CLI RTS ; ;╥ECEIVE A BYTE FROM THE COMPUTER USING THE FAST SERIAL ;PROTOCOL. ; GET = * ; LDA #0 ;┴LLOW ├╠╦ AND ─┴╘┴ TO GO HIGH STA VIA1 ; TO GIVE COMPUTER CONTROL OF THEM LDA #4 - BIT VIA1 ;╫AIT FOR ├╠╦ TO GO LOW BEQ - NOP ;╠ONG DELAY WHILE COMPUTER PREPARES NOP ; FIRST 2 BITS TO SEND NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP LDA VIA1 ;╥EAD SERIAL BUS AND ISOLATE ├╠╦ AND #7 ; AND ─┴╘┴ INPUT LINES (BITS 2 TAX ; AND 1. ┬IT 1 IS ─┴╘┴ OUT) LDA FTABLE1,X ;╠OOK UP PROPER BIT PAIR IN TABLE STA BYTE NOP ;╫AIT FOR NEXT 2 BITS TO BE PUT ON NOP ; SERIAL BUS NOP NOP NOP LDA VIA1 ;╔SOLATE ├╠╦ AND ─┴╘┴ LINES AND AND #7 ; USE TABLE TO LOOK UP BIT PAIR. TAX LDA FTABLE2,X ORA BYTE ;├OMBINE BITS 2 AND 3 (JUST READ) STA BYTE ; WITH BITS 0 AND 1 (ALREADY READ) NOP LDA $FF ;3-CYCLE DELAY NOP LDA VIA1 ;╥EPEAT PROCESS FOR BITS 4 AND 5 AND #7 TAX LDA FTABLE3,X ORA BYTE STA BYTE NOP LDA $FF ;3-CYCLE DELAY NOP LDA VIA1 ;╥EPEAT PROCESS FOR BITS 6 AND 7 AND #7 TAX LDA FTABLE4,X ORA BYTE ;╫E NOW HAVE COMPLETE BYTE RTS ; ;╙END A BYTE TO THE COMPUTER USING THE FASTER SERIAL ;PROTOCOL. ; SEND = * ; STA BYTE ;╙AVE BYTE STY FYTEMP ;╨RESERVE ┘ REGISTER LDA #%00001000 ;┬RING ├╠╦ LOW TO TELL COMPUTER STA VIA1 ; THAT DRIVE IS READY TO SEND LDA #1 ;╫AIT FOR ─┴╘┴ TO GO LOW, WHICH - BIT VIA1 ; MEANS THAT COMPUTER IS READY BEQ - ; TO RECEIVE LDA BYTE ;╥ECALL BYTE TO BE SENT LDY #4 ;╠OOP TO SEND 4 PAIRS OF BITS - STA BYTE ;╙AVE CURRENT BYTE VALUE AND #3 ;╔SOLATE BITS 0 AND 1 AND USE TAX ; TABLE TO LOOK UP PROPER VALUE LDA FTABLE5,X ; TO STORE IN COMMUNICATIONS STA VIA1 ; REGISTER TO REFLECT THOSE BITS LDA BYTE ;╥ECALL CURRENT BYTE LSR ;╙HIFT BYTE RIGHT SO THAT BITS 2 LSR ; AND 3 BECOME BITS 0 AND 1, ETC DEY BNE - ;╥ETURN FOR REMAINING BIT PAIRS LDY FYTEMP ;╟ET BACK ORIGINAL ┘ REGISTER VALUE NOP ;╫AIT FOR COMPUTER TO PROCESS LAST NOP ; BIT PAIR NOP NOP NOP NOP LDA #0 ;┬RING ├╠╦ AND ─┴╘┴ HIGH TO GIVE STA VIA1 ; CONTROL OF SERIAL BUS TO COMPUTER RTS ; ;╘ABLES FOR USE BY DRIVE RECEIVE ROUTINE. ╙INCE THE ├╠╦ ;AND ─┴╘┴ INPUT LINES ARE NOT TWO CONSECUTIVE BITS, IT ;IS NECESSARY TO ISOLATE AN EXTRA BIT, WHICH MEANS THAT ;THERE ARE 8 POSSIBLE VALUES, WHICH YIELD ONLY 4 DIFFERENT ;BIT PAIRS. ┴ SEPARATE TABLE IS USED FOR EACH BIT PAIR ;RECEIVED, IN ORDER TO EASILY CONSTRUCT A COMPLETE BYTE. ;╞╘┴┬╠┼1 HANDLES BITS 0 AND 1, ╞╘┴┬╠┼2 HANDLES BITS 2 AND3, ;AND SO ON. ; FTABLE1 .BYTE %00,%10,%00,%10 .BYTE %01,%11,%01,%11 FTABLE2 .BYTE %0000,%1000,%0000,%1000 .BYTE %0100,%1100,%0100,%1100 FTABLE3 .BYTE %000000,%100000,%000000,%100000 .BYTE %010000,%110000,%010000,%110000 FTABLE4 .BYTE %00000000,%10000000,%00000000,%10000000 .BYTE %01000000,%11000000,%01000000,%11000000 ; ;╘ABLE USED BY DRIVE SEND ROUTINE. ╘HIS TABLE TRANSLATES ;A PAIR OF BITS INTO THE PROPER VALUE TO STORE AT THE ;SERIAL COMMUNICATIONS REGISTER (AT $1800) TO MAKE THE ├╠╦ ;AND ─┴╘┴ LINES REFLECT THOSE BITS. ; FTABLE5 .BYTE %00001010 .BYTE %00001000 .BYTE %00000010 .BYTE %00000000 ; ;┼ND OF DRIVE CODE ; .OFE ;┼NDS OFFSET CODING ; ENDDRIVECODE = * ;═ARKS END OF DRIVE CODE IN ;RELATION TO REGULAR PROGRAM ; .END