; Amdek AMDC-I/II v1.1 firmware disassembly (rev.0.9, CRC32 904CC6B5) ; Disassembled by Avery Lee ; ;=============================================================================== ; Hardware memory map ; ; $0000-03FF 1K static RAM (2 x MM2114N) ; $0800 (R) Read strobe? ; $1000 Printer port? ; D7 (R) Printer BUSY (1 = busy) ; D6 (R) Printer SELECT (0 = printer present) ; D5 (R) AMDC-II flag (1 = second internal drive present) ; D4 (R) Diagnostic mode switch (0 = diagnostic mode) ; $1800 Parallel printer data port ; $2000 MC6850 ACIA control/status register ; D7 (W) Receive interrupt enable ; D6:D5 (W) Transmit control (00 = /RTS low, disable transmit IRQ) ; D4:D2 (W) Word select (101 = 8 data bits + 1 stop bit) ; D1:D0 (W) Counter divide select (00=/1, 01=/16, 10=/64, 11=reset) ; D7 (R) /IRQ ; D6 (R) Parity error ; D5 (R) Receiver overrun ; D4 (R) Framing error ; D3 (R) /CTS (SIO command) ; D2 (R) /DCD (SIO ready) ; D1 (R) Transmit data register empty ; D0 (R) Receive data register full ; $2001 MC6850 ACIA receive/transmit data register ; $4000-4003 FDC (FD1797A-02) ; $6000 Control port ; D0:D1 (W) Drive index ; D3 (W) High speed (1 = ???, 0 = 19200 baud) ; D4 (W) Drive select / motor on ; D5 (W) Printer strobe (1=asserted) ; D6 (W) ?? something disk related - maybe write gate? ; D7 (W) FDC density (1 = FM, 0 = MFM) ; $8000 Drive default density switches ; D0-D3 (R) 0 for single density, 1 for double density ; $8001 ; D0-D1 (R) Starting drive number switches (inverted; %11 = drive 0) ; D2 (R) External drive ID select (0/on = internal drives first, 1/off = external drives first) ; D3 (R) 1050 compatibility switch (0/on = ED only, 1/off = DD enabled) ; ; $C000 (R) Start watchdog timer? ; $F000-FFFF 4K ROM ; ; FDC DRQ -> 6809 FIRQ ; Watchdog -> 6809 NMI ; ??? -> 6809 IRQ ; ;=============================================================================== ; Firmware memory map ; ; $0000-01FF Sector buffer ; $0300 Device ID ; $0301 Command ID ; $0302 AUX1 ; $0303 AUX2 ; $0306 Format timeout ; $0308 Retry counter ; $0309 Bad sector list offset ; $030B Motor off timer counter ; $030D Motor off timer prescaler ; $030F-0312 Device IDs for each drive ; $0313 Selected drive index ; $0314 Current request track number ; $0315 Current request sector number ; $0316-0325 Drive control block 1 ; 0,U Drive status ; D6=1 Write protected ; D5=1 Double density (256 byte sectors) ; D4=1 Motor on ; D3=1 Write protect error ; D2=1 Unsuccessful PUT operation error ; D1=1 Data frame error ; D0=1 Command error ; 1,U FDC status ; 2,U Step rate ; 3,U Current side (0/2 for FDC command bit) ; 4,U Density flag: $80 for FM, $00 for MFM ; 5,U Number of sides (1/2) ; 6,U Track count ; 7,U Current track ; 8,U Current sector size lo ; 9,U Current sector size hi ; 10,U Total sector count hi ; 11,U Total sector count lo ; 12,U ??? ; 13,U Sectors per track hi ; 14,U Sectors per track lo ; $0326-0335 Drive control block 2 ; $0336-0345 Drive control block 3 ; $0346-0355 Drive control block 4 ; $0357-035A Printer control block ; $0357 Printer status ; $0358 Printer mode ; $0359 Printer timeout ; $035F-0360 Exception handler (NMI) ; $0361 Exception handler stack pointer ; $0363 unused? ; $0364 Custom interleave flag -- cleared after non-$66 command ; $0365 Shadow for $6000 ; $0367 Format: size field encoding ; $0368 Format: sector size in words ; $036A Memory command enable flag ; $036B-036F Sector address buffer ; $036C-0385 Format interleave buffer? ; $0391-039A Format layout table ; $0391 Gap I byte count ; $0392 Gap I byte value ; $0393 Gap IIIb byte count ; $0394 Gap IIIb byte value ; $0395 Pre address mark sync byte count ; $0396 Pre address mark sync byte value ; $0397 Gap IIb byte count ; $0398 Gap IIb byte value ; $0399 ; $039A Gap IIIa byte value ; $03A0-03FF Stack ;=============================================================================== ; FIRQ/SWI handler ; F000: 7F035F CLR $035F ;clear exception handler F003: B60800 LDA $0800 F006: 10CE03FF LDS #$03FF ;initialize stack F00A: 1A50 ORCC #$50 ;mask IRQs and FIRQs F00C: BDFC89 JSR $FC89 ;do initialization ;--- main service loop F00F: B62001 LDA $2001 ;read ACIA data to clear receive status F012: B62000 LDA $2000 ;read ACIA status to clear /DCD detect F015: 10BE030B LDY $030B ;get motor off timer counter F019: 2713 BEQ $F02E ;skip if drive not selected F01B: 73030D COM $030D F01E: 260E BNE $F02E F020: 313F LEAY -1,Y ;decrement motor off counter F022: 10BF030B STY $030B ;store motor off counter F026: 2606 BNE $F02E F028: 7F6000 CLR $6000 ;deselect drive and turn off motor F02B: 7F0365 CLR $0365 ;update shadow F02E: B62000 LDA $2000 ;read ACIA status F031: 8504 BITA #$04 ;check /DCD F033: 26DA BNE $F00F ; F035: 8508 BITA #$08 ;check /CTS F037: 27D6 BEQ $F00F F039: 1CEF ANDCC #$EF ;enable IRQs F03B: BDFC0F JSR $FC0F ;receive command frame F03E: 25CF BCS $F00F F040: B60300 LDA $0300 ;get command ID F043: 8140 CMPA #$40 ;check if printer F045: 260F BNE $F056 ;jump if not F047: B61000 LDA $1000 ;read printer status F04A: 8540 BITA #$40 ;check printer /SELECT F04C: 26C1 BNE $F00F ;jump if no printer present F04E: 8EFE7B LDX #$FE7B ;select printer command table F051: CE0357 LDU #$0357 F054: 204B BRA $F0A1 F056: 8D04 BSR $F05C ;try to match against drive F058: 2425 BCC $F07F ;jump if found F05A: 20B3 BRA $F00F ;ignore command, unknown device ID ;=============================================================================== ; Get drive for device ID ; F05C: B60300 LDA $0300 ;get command device ID F05F: 1CFE ANDCC #$FE ;C=0 F061: 8E030E LDX #$030E ;point to device table - 1 F064: C604 LDB #$04 ;four drives to check F066: A185 CMPA B,X ;check if drive device ID matches F068: 2707 BEQ $F071 ;jump if it's this drive F06A: 5A DECB ;next drive F06B: 26F9 BNE $F066 ;jump until all drives checked F06D: 1A01 ORCC #$01 ;C=1 (not found) F06F: 200D BRA $F07E ;return F071: 5A DECB ;B = drive index (0-3) F072: F70313 STB $0313 ;store drive index F075: 58 ASLB ;x2 F076: 58 ASLB ;x4 F077: 58 ASLB ;x8 F078: 58 ASLB ;x16 F079: CE0316 LDU #$0316 ;compute drive control block ptr F07C: 33C5 LEAU B,U ; " F07E: 39 RTS ;=============================================================================== F07F: B60301 LDA $0301 ;get command ID F082: 8153 CMPA #$53 ;check if status command F084: 2710 BEQ $F096 ;jump if so F086: A6C4 LDA ,U F088: 8470 ANDA #$70 F08A: A7C4 STA ,U F08C: BE030B LDX $030B ;get motor off counter F08F: 2705 BEQ $F096 ; F091: 8610 LDA #$10 F093: BDF290 JSR $F290 ;set drive status bit F096: 8EFE32 LDX #$FE32 ;point to memory-protected command table F099: 7D036A TST $036A ;check if mem commands should be enabled F09C: 2703 BEQ $F0A1 ;skip if not F09E: 8EFE29 LDX #$FE29 ;point to full command table F0A1: A680 LDA ,X+ ;get next command in table F0A3: 8100 CMPA #$00 ;check if end of table F0A5: 2611 BNE $F0B8 ;jump if still have entries F0A7: BDFC07 JSR $FC07 ;wait for command to deassert F0AA: 8601 LDA #$01 ;command error bit F0AC: BDF290 JSR $F290 ;set drive status bit F0AF: BDFBFA JSR $FBFA ;short delay F0B2: BDFC7F JSR $FC7F ;send NAK F0B5: 7EF00F JMP $F00F ;restart F0B8: 10AE81 LDY ,X++ ;get command handler pointer F0BB: B10301 CMPA $0301 ;check if command changes F0BE: 26E1 BNE $F0A1 ;keep scanning if not F0C0: ADA4 JSR ,Y ;call command handler F0C2: B60800 LDA $0800 F0C5: B60301 LDA $0301 ;get command ID F0C8: 8166 CMPA #$66 ;check if set interleave command F0CA: 2703 BEQ $F0CF ;skip if not F0CC: 7F0364 CLR $0364 ;clear custom interleave flag F0CF: 7EF00F JMP $F00F ;=============================================================================== ; Get Status command ($53) ; F0D2: BDFC7A JSR $FC7A ;send ACK + Complete F0D5: 5F CLRB F0D6: 1CFE ANDCC #$FE F0D8: A6C4 LDA ,U ;get drive status F0DA: BDFC59 JSR $FC59 ;send byte F0DD: A641 LDA 1,U ;get FDC status F0DF: 88FF EORA #$FF ;invert for 810 emulation F0E1: BDFC59 JSR $FC59 ;send byte F0E4: B60306 LDA $0306 ;get format timeout F0E7: BDFC59 JSR $FC59 ;send byte F0EA: A647 LDA 7,U F0EC: BDFC59 JSR $FC59 ;send byte F0EF: C900 ADCB #$00 ;finalize checksum F0F1: F70305 STB $0305 ;store checksum F0F4: B60305 LDA $0305 ;get checksum F0F7: BDFC59 JSR $FC59 ;send byte F0FA: A6C4 LDA ,U ;load drive status F0FC: 84F8 ANDA #$F8 ;clear unsuccessful PUT and command/data frame error flags F0FE: A7C4 STA ,U F100: 39 RTS ;=============================================================================== ; Put Sector command ($50) ; Write Sector command ($57) ; F101: BDF94B JSR $F94B ;compute track/sector F104: 240D BCC $F113 ;jump if logical sector valid F106: A6C4 LDA ,U ;clear wp, bad put, and command/data error flags F108: 8470 ANDA #$70 F10A: A7C4 STA ,U F10C: 8601 LDA #$01 ;invalid command bit F10E: BDF290 JSR $F290 ;set drive status bit F111: 202C BRA $F13F ;send NAK and exit F113: BDFC6D JSR $FC6D ;send ACK F116: B60301 LDA $0301 ;get command ID F119: 8157 CMPA #$57 ;check if regular speed command F11B: 230D BLS $F12A F11D: 8614 LDA #$14 F11F: B72000 STA $2000 F122: B60365 LDA $0365 ;load control shadow F125: 8A08 ORA #$08 ;set high speed bit F127: B76000 STA $6000 ;write control F12A: BDF163 JSR $F163 ;receive sector F12D: 8615 LDA #$15 F12F: B72000 STA $2000 F132: B60365 LDA $0365 ;get control shadow F135: B76000 STA $6000 ;restore normal speed F138: 2409 BCC $F143 ;jump if frame received OK F13A: 8612 LDA #$12 ;set bad data frame and motor on bits F13C: BDF290 JSR $F290 ;set drive status bit F13F: BDFC7F JSR $FC7F ;send NAK F142: 39 RTS F143: BDFC6D JSR $FC6D ;send ACK F146: BDF991 JSR $F991 ;select drive, motor on, seek to track F149: 250B BCS $F156 F14B: A641 LDA 1,U ;get drive status F14D: 8540 BITA #$40 ;check for write protect F14F: 2709 BEQ $F15A ;jump if not F151: 8608 LDA #$08 ;write protect error F153: BDF290 JSR $F290 ;set drive status bit F156: BDFC84 JSR $FC84 ;send Error F159: 39 RTS F15A: BDF183 JSR $F183 ;do the sector write/verify F15D: 25F7 BCS $F156 ;fail if error F15F: BDFC72 JSR $FC72 ;delay + send Complete F162: 39 RTS ;=============================================================================== ; Receive sector buffer / data frame ; F163: 8E0000 LDX #$0000 F166: 10BE035D LDY $035D F16A: 5F CLRB ;checksum = 0 F16B: 1CFE ANDCC #$FE ;C=0 F16D: BDFC32 JSR $FC32 ;receive data frame F170: F70305 STB $0305 ;store computed checksum F173: BDFC3D JSR $FC3D ;receive checksum F176: B70304 STA $0304 ;store received checksum F179: 1CFE ANDCC #$FE ;C=0 F17B: B10305 CMPA $0305 ;compare checksums F17E: 2702 BEQ $F182 ;exit C=0 if checksum OK F180: 1A01 ORCC #$01 ;exit C=1 if checksum bad F182: 39 RTS ;=============================================================================== ; Write sector (possibly with verify) ; F183: 8604 LDA #$04 F185: B70308 STA $0308 F188: 8EF1BC LDX #$F1BC ;exception handling routine F18B: BF035F STX $035F ;set exception handler F18E: 10FF0361 STS $0361 ;set exception handling stack pointer F192: 8E0000 LDX #$0000 F195: B60315 LDA $0315 ;get sector number F198: B74002 STA $4002 ;set FDC sector number F19B: B6C000 LDA $C000 F19E: 86A8 LDA #$A8 ;write sector command F1A0: AA43 ORA 3,U ;merge in current side F1A2: B74000 STA $4000 ;write FDC command F1A5: E680 LDB ,X+ ;load next byte from buffer F1A7: AC48 CMPX 8,U ;check if at end of sector F1A9: 2E07 BGT $F1B2 ;exit if done F1AB: 53 COMB ;invert for 810 emulation F1AC: 13 SYNC ;wait for DRQ F1AD: F74003 STB $4003 ;write byte to FDC F1B0: 20F3 BRA $F1A5 ;loop back for next byte F1B2: BDFDCF JSR $FDCF ;wait for FDC idle F1B5: B64000 LDA $4000 ;read FDC status F1B8: 8514 BITA #$14 ;check for RNF or Lost Data F1BA: 271B BEQ $F1D7 ;jump if neither F1BC: B64000 LDA $4000 ;read FDC status F1BF: BDF20C JSR $F20C ;force interrupt FDC F1C2: 7A0308 DEC $0308 F1C5: 26CB BNE $F192 F1C7: 1A01 ORCC #$01 F1C9: B64000 LDA $4000 ;read FDC status F1CC: F68001 LDB $8001 ;read switches F1CF: C508 BITB #$08 ;check switch 8 (1050 compatibility) F1D1: 2631 BNE $F204 ; F1D3: 8A10 ORA #$10 ;pretend we got RNF F1D5: 202D BRA $F204 F1D7: B60301 LDA $0301 ;get command F1DA: 8157 CMPA #$57 ;check if it's put sector F1DC: 2624 BNE $F202 ;jump if not F1DE: 8E0000 LDX #$0000 ;init sector buffer pointer F1E1: B6C000 LDA $C000 F1E4: 8688 LDA #$88 ;FDC read sector command F1E6: AA43 ORA 3,U ;merge in current side F1E8: B74000 STA $4000 ;write FDC command F1EB: 13 SYNC ;wait for DRQ F1EC: F64003 LDB $4003 ;read byte from FDC F1EF: 53 COMB ;uninvert for 810 emulation F1F0: E180 CMPB ,X+ ;compare against buffer F1F2: 26C8 BNE $F1BC ;fail if mismatch F1F4: AC48 CMPX 8,U ;check if at end of sector F1F6: 26F3 BNE $F1EB ;loop back if not F1F8: BDFDCF JSR $FDCF ;wait for FDC idle F1FB: B64000 LDA $4000 ;load FDC status F1FE: 850C BITA #$0C ;check for CRC or lost data F200: 26BA BNE $F1BC ;fail if so F202: 1CFE ANDCC #$FE ;C=0 F204: A741 STA 1,U ;save FDC status for drive F206: 8600 LDA #$00 F208: B7035F STA $035F F20B: 39 RTS ;=============================================================================== ; Force interrupt FDC ; F20C: 3412 PSHS A,X F20E: 86D0 LDA #$D0 ;FDC force interrupt command F210: B74000 STA $4000 ;write FDC command F213: 8E0001 LDX #$0001 F216: BDFBFD JSR $FBFD ;delay F219: 3512 PULS X,A F21B: 39 RTS ;=============================================================================== ; Read sector command ($52) ; F21C: BDFC6D JSR $FC6D ;send ACK F21F: BDF94B JSR $F94B ;compute track/sector F222: 240F BCC $F233 ;jump if sector valid F224: A6C4 LDA ,U ;clear wp, bad put, and command/data error flags F226: 8470 ANDA #$70 F228: A7C4 STA ,U F22A: 8601 LDA #$01 F22C: BDF290 JSR $F290 ;set drive status bit F22F: BDFC7F JSR $FC7F ;send NAK F232: 39 RTS F233: BDF991 JSR $F991 ;select drive, motor on, seek to track F236: 2505 BCS $F23D ;fail if error F238: BDF295 JSR $F295 ;read sector F23B: 240F BCC $F24C ;jump if no error F23D: 8604 LDA #$04 F23F: BDF290 JSR $F290 ;set drive status bit F242: 8E0C00 LDX #$0C00 F245: BDFBFD JSR $FBFD ;delay F248: 8645 LDA #$45 ;Error F24A: 2002 BRA $F24E ;send byte F24C: 8643 LDA #$43 ;ACK F24E: BDFC59 JSR $FC59 ;send byte F251: 8E001F LDX #$001F F254: BDFBFD JSR $FBFD ;delay F257: B60301 LDA $0301 ;get command ID F25A: 8172 CMPA #$72 ;check if high-speed read F25C: 260D BNE $F26B ;jump if not F25E: 8614 LDA #$14 ;select /1 divider F260: B72000 STA $2000 ;write ACIA control F263: B60365 LDA $0365 ;read control shadow F266: 8A08 ORA #$08 ;set high speed SIO bit F268: B76000 STA $6000 ;write control F26B: 8D0C BSR $F279 ;send data frame F26D: 8615 LDA #$15 ;select /16 divider F26F: B72000 STA $2000 ;write ACIA control F272: B60365 LDA $0365 ;read control shadow F275: B76000 STA $6000 ;restore control F278: 39 RTS ;=============================================================================== ; Send sector buffer / data frame ; F279: 8E0000 LDX #$0000 F27C: 10BE035D LDY $035D F280: 5F CLRB F281: 1CFE ANDCC #$FE F283: BDFC4E JSR $FC4E ;send data frame F286: F70305 STB $0305 ;store computed checksum F289: B60305 LDA $0305 ;get checksum F28C: BDFC59 JSR $FC59 ;send byte F28F: 39 RTS ;=============================================================================== ; Set drive status bit ; F290: AAC4 ORA ,U F292: A7C4 STA ,U F294: 39 RTS ;=============================================================================== ; Read sector ; F295: 8601 LDA #$01 F297: B70308 STA $0308 F29A: 8EF2CC LDX #$F2CC F29D: BF035F STX $035F ;set exception handler F2A0: 10FF0361 STS $0361 ;set exception handler stack pointer F2A4: 8E0000 LDX #$0000 F2A7: B6C000 LDA $C000 ;arm watchdog timer F2AA: B60315 LDA $0315 ;get desired sector F2AD: B74002 STA $4002 ;write FDC sector F2B0: 8688 LDA #$88 ;read sector F2B2: AA43 ORA 3,U ;merge in current side flag F2B4: B74000 STA $4000 ;write FDC command F2B7: 13 SYNC ;wait for DRQ F2B8: F64003 LDB $4003 ;load byte from FDC F2BB: 53 COMB ;invert for 810 emulation F2BC: E780 STB ,X+ ;store to buffer F2BE: AC48 CMPX 8,U ;check if sector done F2C0: 26F5 BNE $F2B7 ;continue if not F2C2: BDFDCF JSR $FDCF ;wait for FDC idle F2C5: B64000 LDA $4000 ;read FDC status F2C8: 853C BITA #$3C ;check deleted, RNF, CRC, lost data F2CA: 2720 BEQ $F2EC ;jump if no error F2CC: B64000 LDA $4000 ;read FDC status again F2CF: BDF20C JSR $F20C ;force interrupt FDC F2D2: 7A0308 DEC $0308 F2D5: 2CCD BGE $F2A4 F2D7: F60356 LDB $0356 F2DA: 2703 BEQ $F2DF F2DC: 7C0369 INC $0369 F2DF: 1A01 ORCC #$01 F2E1: F68001 LDB $8001 ;get switches F2E4: C508 BITB #$08 ;check 1050 compat F2E6: 2606 BNE $F2EE F2E8: 8A10 ORA #$10 ;force RNF F2EA: 2002 BRA $F2EE F2EC: 1CFE ANDCC #$FE F2EE: 8520 BITA #$20 ;check deleted error F2F0: 2702 BEQ $F2F4 ;skip if not F2F2: 8A40 ORA #$40 ;copy to bit 6 for 810 FD1771 emulation F2F4: A741 STA 1,U ;set FDC status F2F6: 8600 LDA #$00 F2F8: B7035F STA $035F F2FB: 39 RTS ;=============================================================================== ; Toggle density ; F2FC: A644 LDA 4,U ;get density flag F2FE: 2610 BNE $F310 ;jump if single density F300: 8E02D0 LDX #$02D0 ;set 720 total sectors F303: AF4A STX 10,U F305: 8E0012 LDX #$0012 ;set 18 sectors per track F308: AF4D STX 13,U F30A: 8680 LDA #$80 ;set FM encoding F30C: A744 STA 4,U F30E: 200E BRA $F31E F310: 8E0400 LDX #$0400 ;set 1024 total sectors F313: AF4A STX 10,U F315: 8E001A LDX #$001A ;set 26 sectors per track F318: AF4D STX 13,U F31A: 8600 LDA #$00 ;set MFM encoding F31C: A744 STA 4,U ;get encoding flag F31E: 8A10 ORA #$10 ;drive on F320: BA0313 ORA $0313 ;merge drive index F323: B76000 STA $6000 ;write control F326: B70365 STA $0365 F329: BDF94B JSR $F94B ;compute track/sector F32C: 39 RTS ;=============================================================================== ; Format command ($21) ; F32D: BDFC6D JSR $FC6D ;send ACK F330: B60356 LDA $0356 F333: 2703 BEQ $F338 F335: BDFACD JSR $FACD ;select single density F338: 8EF3A9 LDX #$F3A9 ;select single density layout F33B: 108EF62D LDY #$F62D ;select single density interleave F33F: 6D44 TST 4,U F341: 2612 BNE $F355 F343: 8EF3B3 LDX #$F3B3 ;select medium density layout F346: 108EF640 LDY #$F640 ;select medium density interleave F34A: 6D48 TST 8,U F34C: 2707 BEQ $F355 F34E: 8EF3BD LDX #$F3BD ;select double density layout F351: 108EF61A LDY #$F61A ;select double density interleave F355: 3420 PSHS Y F357: 108E0391 LDY #$0391 ;temporary layout table F35B: C60A LDB #$0A ;copy layout table to temp buffer F35D: A680 LDA ,X+ F35F: A7A0 STA ,Y+ F361: 5A DECB F362: 26F9 BNE $F35D F364: 3520 PULS Y F366: EC48 LDD 8,U ;get sector size F368: FD035D STD $035D F36B: B70367 STA $0367 ;set size encoding from sector size high F36E: 44 LSRA ;divide sector size by two F36F: 56 RORB F370: F70368 STB $0368 ;set word count for writing data field F373: 7D0364 TST $0364 ;check if custom interleave has been set F376: 2704 BEQ $F37C ;skip if not F378: 108E036B LDY #$036B ;use custom interleave table F37C: BDF5CB JSR $F5CB F37F: 240D BCC $F38E F381: BDF20C JSR $F20C ;force interrupt FDC F384: 6F4C CLR 12,U F386: BDFC84 JSR $FC84 ;send Error F389: BDFBFA JSR $FBFA ;short delay F38C: 2014 BRA $F3A2 F38E: BDF417 JSR $F417 F391: 25EE BCS $F381 F393: B60800 LDA $0800 F396: BDF5AE JSR $F5AE F399: BDFDA2 JSR $FDA2 F39C: BDFC72 JSR $FC72 ;delay + send Complete F39F: BDFBFA JSR $FBFA ;short delay F3A2: 8E0000 LDX #$0000 F3A5: BDF279 JSR $F279 ;send data frame F3A8: 39 RTS ;=============================================================================== ; Single density layout ; F3A9: 19FF F3AB: 0400 F3AD: 0100 F3AF: 0200 F3B1: 14FF ;=============================================================================== ; Medium density layout ; F3B3: 324E F3B5: 1F4E F3B7: 03F5 F3B9: 124E F3BB: 324E ;=============================================================================== ; Double density layout ; F3BD: 324E F3BF: 154E F3C1: 03F5 F3C3: 124E F3C5: 1E4E ;=============================================================================== ; Set interleave command ($66) ; ; Receives a 26-byte frame containing the custom interleave to use for the next ; command, which must be a format command. Any other disk command will clear ; the custom interleave. ; ; Note that this is NOT the same as the US Doubler's format skewed ($66) ; command, which takes a whole sector buffer and immediately begins formatting. ; F3C7: BDFC6D JSR $FC6D ;send ACK F3CA: 8E036C LDX #$036C F3CD: 108E001A LDY #$001A ;data frame len = 26 bytes F3D1: BDF16A JSR $F16A ;receive data frame F3D4: 2407 BCC $F3DD ;jump if data frame OK F3D6: BDFBFA JSR $FBFA ;short delay F3D9: BDFC7F JSR $FC7F ;send NAK F3DC: 39 RTS F3DD: BDFC7A JSR $FC7A ;send ACK + Complete F3E0: 7C0364 INC $0364 ;enable custom interleave F3E3: 7F036B CLR $036B F3E6: 39 RTS ;=============================================================================== ; Format medium command ($22) ; Set medium density command ($74) ; F3E7: 8E0080 LDX #$0080 ;set 128 bytes per sector F3EA: AF48 STX 8,U F3EC: 8E001A LDX #$001A ;set 26 sectors per track F3EF: AF4D STX 13,U F3F1: 8600 LDA #$00 F3F3: A744 STA 4,U F3F5: 8610 LDA #$10 F3F7: A7C4 STA ,U F3F9: 8628 LDA #$28 ;set 40 tracks F3FB: A746 STA 6,U F3FD: 8601 LDA #$01 ;set single sided F3FF: A745 STA 5,U F401: 8E0400 LDX #$0400 ;set 1024 total sectors F404: AF4A STX 10,U F406: B60301 LDA $0301 F409: 8174 CMPA #$74 ;check if $74 command F40B: 2703 BEQ $F410 ;skip if so F40D: 7EF32D JMP $F32D ;begin format now for $22 F410: BDFC6D JSR $FC6D ;send ACK F413: BDFC72 JSR $FC72 ;short delay and send Complete F416: 39 RTS ;=============================================================================== F417: 8EF562 LDX #$F562 F41A: BF035F STX $035F ;set exception handler F41D: 10FF0361 STS $0361 ;set exception handler stack pointer F421: 6F43 CLR 3,U ;set DCB to side 1 F423: 8E0000 LDX #$0000 F426: BF0309 STX $0309 F429: E646 LDB 6,U F42B: B6C000 LDA $C000 ;reset watchdog timer F42E: 8E07FF LDX #$07FF F431: BDFBFD JSR $FBFD ;delay F434: B6C000 LDA $C000 ;reset watchdog timer F437: 3404 PSHS B F439: 86F0 LDA #$F0 ;FDC write track command F43B: AA43 ORA 3,U ;merge in side select bit F43D: B74000 STA $4000 ;write FDC command F440: F60391 LDB $0391 F443: B60392 LDA $0392 F446: 13 SYNC F447: B74003 STA $4003 F44A: 5A DECB F44B: 26F9 BNE $F446 F44D: E64E LDB 14,U ;get sectors per track F44F: 3404 PSHS B ;save it F451: F60393 LDB $0393 F454: B60394 LDA $0394 F457: 13 SYNC F458: B74003 STA $4003 F45B: 5A DECB F45C: 26F9 BNE $F457 F45E: C60C LDB #$0C F460: 8600 LDA #$00 F462: 13 SYNC F463: B74003 STA $4003 F466: 5A DECB F467: 26F9 BNE $F462 F469: F60395 LDB $0395 ;get sync byte count F46C: B60396 LDA $0396 ;get sync byte value F46F: 13 SYNC F470: B74003 STA $4003 F473: 5A DECB F474: 26F9 BNE $F46F F476: 86FE LDA #$FE ;IDAM F478: 13 SYNC F479: B74003 STA $4003 ;write to FDC F47C: B64001 LDA $4001 ;track number F47F: 13 SYNC F480: B74003 STA $4003 ;write to FDC as track F483: A643 LDA 3,U ;get FDC side select bit F485: 44 LSRA ;convert to 0/1 F486: 13 SYNC ;wait for DRQ F487: B74003 STA $4003 ;write to FDC as side number F48A: E6E4 LDB ,S F48C: A6A5 LDA B,Y ;read sector from interleave table F48E: 13 SYNC ;wait for DRQ F48F: B74003 STA $4003 ;write to FDC as sector number F492: B60367 LDA $0367 ;load size encoding F495: 13 SYNC ;wait for DRQ F496: B74003 STA $4003 ;write to FDC as size field F499: 86F7 LDA #$F7 ;CRC-16 token F49B: 13 SYNC ;wait for DRQ F49C: B74003 STA $4003 ;write to FDC to write CRC-16 F49F: F60397 LDB $0397 F4A2: B60398 LDA $0398 F4A5: 13 SYNC ;wait for DRQ F4A6: B74003 STA $4003 ;write byte to FDC F4A9: 5A DECB F4AA: 26F9 BNE $F4A5 F4AC: C60C LDB #$0C F4AE: 8600 LDA #$00 F4B0: 13 SYNC ;wait for DRQ F4B1: B74003 STA $4003 ;write byte to FDC F4B4: 5A DECB F4B5: 26F9 BNE $F4B0 F4B7: F60395 LDB $0395 ;get sync byte count F4BA: B60396 LDA $0396 ;get sync byte value F4BD: 13 SYNC ;wait for DRQ F4BE: B74003 STA $4003 ;write byte to FDC F4C1: 5A DECB F4C2: 26F9 BNE $F4BD F4C4: 86FB LDA #$FB ;DAM F4C6: 13 SYNC ;wait for DRQ F4C7: B74003 STA $4003 ;write byte to FDC F4CA: F60368 LDB $0368 F4CD: 866B LDA #$6B ;first half of $6BB6 F4CF: 13 SYNC ;wait for DRQ F4D0: B74003 STA $4003 ;write byte to FDC F4D3: 86B6 LDA #$B6 ;second half of $6BB6 F4D5: 13 SYNC ;wait for DRQ F4D6: B74003 STA $4003 ;write byte to FDC F4D9: 5A DECB F4DA: 26F1 BNE $F4CD F4DC: 86F7 LDA #$F7 ;FDC CRC-16 token F4DE: 13 SYNC ;wait for DRQ F4DF: B74003 STA $4003 ;write byte to FDC F4E2: B6039A LDA $039A F4E5: 3504 PULS B F4E7: 13 SYNC F4E8: B74003 STA $4003 F4EB: 5A DECB ;decrement sector count F4EC: 1026FF5F LBNE $F44F ;loop back until all sectors done F4F0: B74003 STA $4003 F4F3: F64000 LDB $4000 ;get FDC status F4F6: C501 BITB #$01 ;check BSY F4F8: 26F6 BNE $F4F0 ;keep looping if so F4FA: BDFDCF JSR $FDCF ;wait for FDC idle F4FD: BDF20C JSR $F20C ;force interrupt FDC F500: BDF571 JSR $F571 ;verify track F503: A645 LDA 5,U ;get side count F505: 8101 CMPA #$01 ;check if single sided F507: 2722 BEQ $F52B ;skip if so F509: A643 LDA 3,U ;get current side F50B: 261E BNE $F52B ;skip if side 2 F50D: 8602 LDA #$02 ;switch to side 2 F50F: A743 STA 3,U F511: 8D05 BSR $F518 ;update FDC side select output F513: 3504 PULS B F515: 16FF13 LBRA $F42B F518: 8688 LDA #$88 ;read sector F51A: AA43 ORA 3,U ;merge in current side F51C: B74000 STA $4000 ;write FDC command F51F: BDFBFA JSR $FBFA ;short delay F522: 86D0 LDA #$D0 ;FDC force interrupt command F524: B74000 STA $4000 ;write FDC command F527: BDFBFA JSR $FBFA ;short delay F52A: 39 RTS F52B: 3504 PULS B F52D: 5A DECB F52E: 261E BNE $F54E F530: 8EFFFF LDX #$FFFF F533: 10AE48 LDY 8,U ;get sector size F536: 313E LEAY -2,Y ;move to last word offset F538: AFA4 STX ,Y ;store terminator F53A: 10BE0309 LDY $0309 ; F53E: 8EFFFF LDX #$FFFF F541: AFA4 STX ,Y F543: B64000 LDA $4000 ;get FDC status F546: A741 STA 1,U ;store in DCB F548: 7F035F CLR $035F F54B: 1CFE ANDCC #$FE F54D: 39 RTS F54E: 6F43 CLR 3,U F550: 8DC6 BSR $F518 ;update FDC side select output F552: 8658 LDA #$58 ;FDC step in command F554: AA42 ORA 2,U ;merge in step rate F556: B74000 STA $4000 ;write FDC command F559: BDFBFA JSR $FBFA ;short delay F55C: BDFDCF JSR $FDCF ;wait for FDC idle F55F: 16FEC9 LBRA $F42B ;=============================================================================== ; Format exception handler ; F562: 10BE0309 LDY $0309 ;get bad sector list offset F566: 8EFFFF LDX #$FFFF ;write terminator F569: AFA4 STX ,Y F56B: 7F035F CLR $035F F56E: 1A01 ORCC #$01 F570: 39 RTS ;=============================================================================== ; Format: verify track ; F571: E64E LDB 14,U ;get sectors per track count F573: B6C000 LDA $C000 ;reset watchdog timer F576: AE48 LDX 8,U ;get current sector size lo F578: A6A5 LDA B,Y ;get sector from interleave table F57A: B74002 STA $4002 ;write FDC sector F57D: 8688 LDA #$88 ;FDC read sector command F57F: AA43 ORA 3,U ;merge in side select F581: B74000 STA $4000 ;write FDC command F584: BDFDD7 JSR $FDD7 ;wait for FDC busy F587: 13 SYNC ;wait for DRQ F588: B64003 LDA $4003 ;read FDC data byte F58B: 301F LEAX -1,X ;decrement byte count F58D: 26F8 BNE $F587 ;jump if still bytes left F58F: BDFDCF JSR $FDCF ;wait for FDC idle F592: B64000 LDA $4000 ;read FDC status F595: 8518 BITA #$18 ;check for RNF, CRC F597: 2711 BEQ $F5AA ;jump if neither F599: 3420 PSHS Y ;save interleave table pointer F59B: 10BE0309 LDY $0309 ;get bad sector list offset F59F: BE4001 LDX $4001 ;read FDC track/sector number F5A2: AFA1 STX ,Y++ ;store bad track/sector F5A4: 10BF0309 STY $0309 ;save bad sector list offset F5A8: 3520 PULS Y ;restore interleave table pointer F5AA: 5A DECB ;next sector F5AB: 26C6 BNE $F573 ;jump back until all sectors done F5AD: 39 RTS F5AE: 108E0000 LDY #$0000 F5B2: 10BC0309 CMPY $0309 F5B6: 2712 BEQ $F5CA F5B8: E6A0 LDB ,Y+ F5BA: A64E LDA 14,U F5BC: 3D MUL F5BD: 1F01 TFR D,X F5BF: E6A0 LDB ,Y+ F5C1: 3A ABX F5C2: 1F10 TFR X,D F5C4: E73E STB -2,Y F5C6: A73F STA -1,Y F5C8: 20E8 BRA $F5B2 F5CA: 39 RTS ;=============================================================================== F5CB: B60313 LDA $0313 ;get selected drive index F5CE: 8A10 ORA #$10 ;motor/drive on bit F5D0: AA44 ORA 4,U ;merge in encoding flag F5D2: B76000 STA $6000 ;write control F5D5: B70365 STA $0365 F5D8: 8EAFFF LDX #$AFFF F5DB: BF030B STX $030B ;set motor off timer F5DE: BDFC02 JSR $FC02 ;delay F5E1: BDFC02 JSR $FC02 ;delay F5E4: BDF20C JSR $F20C ;force interrupt FDC F5E7: B64000 LDA $4000 ;get FDC status F5EA: 8540 BITA #$40 ;check for write protect error F5EC: 270E BEQ $F5FC ;jump if not F5EE: 8608 LDA #$08 ;unsuccessful put error F5F0: BDF290 JSR $F290 ;set drive status bit F5F3: B64000 LDA $4000 ;get FDC status F5F6: A741 STA 1,U ;save in DCB F5F8: 1A01 ORCC #$01 ;exit C=1 (error) F5FA: 201D BRA $F619 F5FC: BDFC02 JSR $FC02 ;delay F5FF: BDFC02 JSR $FC02 ;delay F602: BDFDA2 JSR $FDA2 ;recalibrate drive F605: B64000 LDA $4000 ;read FDC status F608: 25EC BCS $F5F6 ;jump if recalibrate failed F60A: 8E0000 LDX #$0000 ;clear sector buffer F60D: CC0000 LDD #$0000 F610: ED81 STD ,X++ F612: 8C0100 CMPX #$0100 F615: 25F9 BCS $F610 F617: 1CFE ANDCC #$FE ;exit C=0 (success) F619: 39 RTS ;=============================================================================== ; Double density interleave table ; F61A: 00 0E 08 02 0F 09 03 10 0A 04 11 0B 05 12 0C 06 0D 07 01 ;=============================================================================== ; Single density interleave table ; F62D: 00 02 04 06 08 0A 0C 0E 10 12 01 03 05 07 09 0B 0D 0F 11 ;=============================================================================== ; Medium density interleave table ; F640: 00 02 04 06 08 0A 0C 0E 10 12 14 16 18 1A F64E: 01 03 05 07 09 0B 0D 0F 11 13 15 17 19 ;=============================================================================== ; Read PERCOM Block command ($4E) ; F65B: BDFC7A JSR $FC7A ;send ACK + Complete F65E: 5F CLRB ;clear checksum F65F: 1CFE ANDCC #$FE ;clear carry for checksum computation F661: A646 LDA 6,U ;get track count F663: BDFC59 JSR $FC59 ;send byte F666: A642 LDA 2,U ;get step rate F668: BDFC59 JSR $FC59 ;send byte F66B: A64D LDA 13,U ;get sectors per track hi F66D: BDFC59 JSR $FC59 ;send byte F670: A64E LDA 14,U ;get sectors per track lo F672: BDFC59 JSR $FC59 ;send byte F675: A645 LDA 5,U ;get number of sides F677: 4A DECA ;compute sides-1 F678: BDFC59 JSR $FC59 ;send byte F67B: A644 LDA 4,U ;get density encoding F67D: 2B04 BMI $F683 ;skip if FM F67F: 8604 LDA #$04 ;indicate MFM F681: 2002 BRA $F685 F683: 8600 LDA #$00 ;indicate FM F685: BDFC59 JSR $FC59 ;send byte F688: A648 LDA 8,U ;get bytes per sector hi F68A: BDFC59 JSR $FC59 ;send byte F68D: A649 LDA 9,U ;get bytes per sector lo F68F: BDFC59 JSR $FC59 ;send byte F692: 86FF LDA #$FF ;indicate drive active F694: BDFC59 JSR $FC59 ;send byte F697: 8615 LDA #$15 F699: BDFC59 JSR $FC59 ;send byte F69C: 8600 LDA #$00 F69E: BDFC59 JSR $FC59 ;send byte F6A1: BDFC59 JSR $FC59 ;send byte F6A4: C900 ADCB #$00 ;fold final carry F6A6: 1F98 TFR B,A ;get checksum F6A8: BDFC59 JSR $FC59 ;send byte F6AB: 39 RTS ;=============================================================================== ; Write PERCOM Block command ($4F) ; F6AC: BDFC6D JSR $FC6D ;send ACK F6AF: 8E0000 LDX #$0000 F6B2: 108E000C LDY #$000C F6B6: BDF16A JSR $F16A F6B9: 2407 BCC $F6C2 F6BB: BDFBFA JSR $FBFA ;short delay F6BE: BDFC7F JSR $FC7F ;send NAK F6C1: 39 RTS F6C2: BDFC6A JSR $FC6A ;delay + send ACK F6C5: 8E0000 LDX #$0000 F6C8: A680 LDA ,X+ F6CA: A746 STA 6,U ;set DCB track count F6CC: A680 LDA ,X+ F6CE: 8403 ANDA #$03 F6D0: A742 STA 2,U ;set DCB step rate F6D2: EC81 LDD ,X++ F6D4: ED4D STD 13,U ;set DCB sectors per track hi F6D6: A680 LDA ,X+ F6D8: 4C INCA F6D9: A745 STA 5,U ;set DCB side count F6DB: A680 LDA ,X+ F6DD: 2604 BNE $F6E3 F6DF: 8680 LDA #$80 F6E1: 2002 BRA $F6E5 F6E3: 8600 LDA #$00 F6E5: A744 STA 4,U ;set DCB density encoding F6E7: EC84 LDD ,X F6E9: ED48 STD 8,U ;set DCB sector size F6EB: A648 LDA 8,U F6ED: 2708 BEQ $F6F7 F6EF: A6C4 LDA ,U ;set double density in DCB drive status F6F1: 8A20 ORA #$20 F6F3: A7C4 STA ,U F6F5: 2006 BRA $F6FD F6F7: A6C4 LDA ,U ;clear double density in DCB drive status F6F9: 84DF ANDA #$DF F6FB: A7C4 STA ,U F6FD: 6F41 CLR 1,U ;clear FDC status F6FF: A646 LDA 6,U ;get track count F701: E645 LDB 5,U ;get side count F703: 3D MUL ;compute total tracks F704: A64E LDA 14,U ;get sectors per track F706: 3D MUL ;compute total sectors F707: ED4A STD 10,U ;set DCB total sector count F709: BDFC72 JSR $FC72 ;delay + send Complete F70C: 39 RTS ;=============================================================================== ; Get drive device IDs command handler ($63) ; ; Sends a 4-byte frame containing the device IDs for all drives. ; F70D: BDFC7A JSR $FC7A ;send ACK + Complete F710: BDFBFA JSR $FBFA ;short delay F713: 8E030F LDX #$030F ;drive device ID table F716: 108E0004 LDY #$0004 ;4 device IDs to send F71A: BDF280 JSR $F280 ;send frame F71D: 39 RTS ;=============================================================================== ; Set drive device IDs command handler ($64) ; ; Receives a 4-byte data frame and then sets the device IDs for all drives. ; F71E: BDFC6D JSR $FC6D ;send ACK F721: 8E0000 LDX #$0000 F724: 108E0004 LDY #$0004 ;4 device IDs to receive F728: BDF16A JSR $F16A ;receive data frame F72B: 2407 BCC $F734 F72D: BDFBFA JSR $FBFA ;short delay F730: BDFC7F JSR $FC7F ;send NAK F733: 39 RTS F734: BDFC6A JSR $FC6A ;delay + send ACK F737: DC00 LDD $00 ;copy IDs to drive device ID table F739: FD030F STD $030F F73C: DC02 LDD $02 F73E: FD0311 STD $0311 F741: BDFC72 JSR $FC72 ;delay + send Complete F744: 39 RTS ;=============================================================================== ; Reset command handler ($78) ; F745: BDFC6D JSR $FC6D ;send ACK F748: BDFC89 JSR $FC89 ;reset F74B: BDFC75 JSR $FC75 ;send Complete F74E: 39 RTS ;=============================================================================== ; Get drive count command handler ($69) ; ; Returns a single byte data frame containing the number of drives found ; starting at the given device ID. Command is NAKed if the device ID used is ; not of the first drive. ; F74F: B68001 LDA $8001 ;read non-density switches F752: 43 COMA ;uninvert F753: 8403 ANDA #$03 ;read switches 5 and 6 (starting drive) F755: 4C INCA ;map to 1-4 F756: 8A30 ORA #$30 ;map to $31-34 device ID F758: B10300 CMPA $0300 ;see if it matches command's device ID F75B: 270C BEQ $F769 ;jump if so F75D: 8601 LDA #$01 ;command error bit F75F: BDF290 JSR $F290 ;set drive status bit F762: BDFBFA JSR $FBFA ;short delay F765: BDFC7F JSR $FC7F ;send NAK F768: 39 RTS F769: BDFC7A JSR $FC7A ;send ACK + Complete F76C: B60366 LDA $0366 F76F: BDFC59 JSR $FC59 ;send byte F772: BDFC59 JSR $FC59 ;send byte F775: 39 RTS ;=============================================================================== ; Check disk command handler ($43) ; ; Checks for a disk in the drive and returns a single byte frame with $00 for ; no disk, $01 for FM, or $02 for MFM. ; F776: BDF20C JSR $F20C ;force interrupt FDC F779: BDFC6D JSR $FC6D ;send ACK F77C: B60313 LDA $0313 ;get selected drive index F77F: 8A10 ORA #$10 ;motor on F781: B76000 STA $6000 ;write control F784: BDFC02 JSR $FC02 ;delay F787: 10BE030B LDY $030B ;check if motor was on F78B: 2608 BNE $F795 ;skip spin-up delay if so F78D: C604 LDB #$04 F78F: BDFC02 JSR $FC02 ;delay F792: 5A DECB F793: 26FA BNE $F78F F795: 108EAFFF LDY #$AFFF ;motor off timer duration F799: 10BF030B STY $030B ;set motor off timer F79D: 6F4C CLR 12,U F79F: BDFDA2 JSR $FDA2 ;recalibrate drive F7A2: F64000 LDB $4000 ;read FDC status F7A5: C402 ANDB #$02 ;check for index pulse F7A7: F7037E STB $037E F7AA: 8E3000 LDX #$3000 F7AD: B64000 LDA $4000 ;read FDC status F7B0: 8402 ANDA #$02 ;check for index pulse F7B2: B1037E CMPA $037E ;look for IP edge F7B5: 2608 BNE $F7BF ;jump if so F7B7: 301F LEAX -1,X F7B9: 26F2 BNE $F7AD F7BB: C600 LDB #$00 F7BD: 200B BRA $F7CA F7BF: BDFA84 JSR $FA84 ;detect density F7C2: C601 LDB #$01 F7C4: A644 LDA 4,U ;get encoding flag F7C6: 2602 BNE $F7CA ;skip if FM F7C8: C602 LDB #$02 F7CA: 3404 PSHS B F7CC: BDFC75 JSR $FC75 ;send Complete F7CF: 3502 PULS A F7D1: BDFC59 JSR $FC59 ;send byte F7D4: BDFC59 JSR $FC59 ;send byte F7D7: 39 RTS ;=============================================================================== ; Set single density command ($75) ; F7D8: BDFC6D JSR $FC6D ;send ACK F7DB: BDFACD JSR $FACD ;select single density F7DE: BDFC72 JSR $FC72 ;delay + send Complete F7E1: 39 RTS ;=============================================================================== ; Set double density command ($76) ; F7E2: BDFC6D JSR $FC6D ;send ACK F7E5: BDFAED JSR $FAED ;switch to MFM F7E8: 8E02D0 LDX #$02D0 ;set 720 total sectors F7EB: AF4A STX 10,U F7ED: 8628 LDA #$28 ;set 40 tracks F7EF: A746 STA 6,U F7F1: 8601 LDA #$01 ;set single sided F7F3: A745 STA 5,U F7F5: 6F43 CLR 3,U ;select side 1 F7F7: BDFC72 JSR $FC72 ;delay + send Complete F7FA: 39 RTS ;=============================================================================== ; Get version command handler ($56) ; F7FB: BDFC7A JSR $FC7A ;send ACK + Complete F7FE: BDFBFA JSR $FBFA ;short delay F801: 8EF80C LDX #$F80C F804: 108E0019 LDY #$0019 F808: BDF280 JSR $F280 ;send frame F80B: 39 RTS F80C: 20 ' ' F80D: 414D44432020 'AMDC ' F813: 56455220312E31 'VER 1.1' F81A: 20202020 ' ' F81E: 312F33302F3834 '1/30/84' ;=============================================================================== ; Read switches command ($73) ; F825: B68000 LDA $8000 F828: 840F ANDA #$0F F82A: B7036B STA $036B F82D: B68001 LDA $8001 F830: 8407 ANDA #$07 F832: 48 ASLA F833: 48 ASLA F834: 48 ASLA F835: 48 ASLA F836: BA036B ORA $036B F839: B7036B STA $036B F83C: B61000 LDA $1000 F83F: 8410 ANDA #$10 F841: 48 ASLA F842: 48 ASLA F843: 48 ASLA F844: BA036B ORA $036B F847: B7036B STA $036B F84A: BDFC7A JSR $FC7A ;send ACK + Complete F84D: B6036B LDA $036B F850: BDFC59 JSR $FC59 ;send byte F853: BDFC59 JSR $FC59 ;send byte F856: 39 RTS ;=============================================================================== ; Get drive speed command handler ($71) ; F857: BDFC6D JSR $FC6D ;send ACK F85A: B60313 LDA $0313 ;get selected drive index F85D: 8A10 ORA #$10 ;motor on F85F: B76000 STA $6000 ;write control F862: B70365 STA $0365 ;update shadow F865: BDF20C JSR $F20C ;force interrupt FDC F868: 8E030B LDX #$030B ;!! - BUG - should be just $030B F86B: 2618 BNE $F885 ;jump if motor already on F86D: BDFC02 JSR $FC02 ;delay F870: BDFC02 JSR $FC02 ;delay F873: BDFC02 JSR $FC02 ;delay F876: BDFC02 JSR $FC02 ;delay F879: BDFC02 JSR $FC02 ;delay F87C: BDFC02 JSR $FC02 ;delay F87F: BDFC02 JSR $FC02 ;delay F882: BDFC02 JSR $FC02 ;delay F885: 108EAFFF LDY #$AFFF ;set motor off timer F889: 10BF030B STY $030B ; " F88D: 108E0000 LDY #$0000 ; F891: 7F036B CLR $036B F894: 8EF904 LDX #$F904 ;set exception handler F897: BF035F STX $035F F89A: 10FF0361 STS $0361 ;set exception stack pointer F89E: F6C000 LDB $C000 ;restart watchdog F8A1: B64000 LDA $4000 ;get FDC status F8A4: 8502 BITA #$02 ;check for index pulse F8A6: 27F9 BEQ $F8A1 ;keep waiting for one if not F8A8: B64000 LDA $4000 ;get FDC status F8AB: 8502 BITA #$02 ;check for index pulse F8AD: 26F9 BNE $F8A8 ;wait until trailing edge F8AF: F6C000 LDB $C000 ;restart watchdog F8B2: 8E0017 LDX #$0017 F8B5: 7D036B TST $036B F8B8: 260C BNE $F8C6 F8BA: B64000 LDA $4000 ;get FDC status F8BD: 8502 BITA #$02 ;check for index pulse F8BF: 270C BEQ $F8CD F8C1: 7C036B INC $036B F8C4: 2007 BRA $F8CD F8C6: B64000 LDA $4000 F8C9: 8502 BITA #$02 F8CB: 270F BEQ $F8DC F8CD: 301F LEAX -1,X F8CF: 26E4 BNE $F8B5 F8D1: 3121 LEAY 1,Y F8D3: 21FE BRN $F8D3 F8D5: 21FE BRN $F8D5 F8D7: 12 NOP F8D8: 12 NOP F8D9: 12 NOP F8DA: 20D6 BRA $F8B2 F8DC: 7F035F CLR $035F F8DF: B60800 LDA $0800 F8E2: 8C000B CMPX #$000B F8E5: 2E02 BGT $F8E9 F8E7: 3121 LEAY 1,Y F8E9: 10BF036B STY $036B F8ED: CC0258 LDD #$0258 ;600 F8F0: B3036B SUBD $036B ;600-Y F8F3: FD036B STD $036B F8F6: BDFC75 JSR $FC75 ;send Complete F8F9: 108E0002 LDY #$0002 ;two bytes to send F8FD: 8E036B LDX #$036B ;set transfer pointer F900: BDF280 JSR $F280 ;send frame F903: 39 RTS F904: 7F035F CLR $035F F907: BDFC84 JSR $FC84 ;send Error F90A: 39 RTS ;=============================================================================== ; Write memory ($58) ; ; Writes 128 bytes of memory to the address in AUX1/2. ; F90B: BDFC6D JSR $FC6D ;send ACK F90E: B60303 LDA $0303 F911: F60302 LDB $0302 F914: 1F01 TFR D,X ;set transfer address to AUX1/2 F916: 108E0080 LDY #$0080 ;transfer length is 128 bytes F91A: BDF16A JSR $F16A ;receive data frame F91D: 2407 BCC $F926 ;jump if received OK F91F: BDFBFA JSR $FBFA ;short delay F922: BDFC7F JSR $FC7F ;send NAK F925: 39 RTS F926: BDFC7A JSR $FC7A ;send ACK + Complete F929: 39 RTS ;=============================================================================== ; Read memory ($59) ; ; Reads 128 bytes of memory to the address in AUX1/2. ; F92A: BDFC7A JSR $FC7A ;send ACK + Complete F92D: BDFBFA JSR $FBFA ;short delay F930: B60303 LDA $0303 F933: F60302 LDB $0302 F936: 1F01 TFR D,X ;set transfer address to AUX1/2 F938: 108E0080 LDY #$0080 ;transfer length is 128 bytes F93C: BDF280 JSR $F280 ;send frame F93F: 39 RTS ;=============================================================================== ; Execute command ($5A) ; F940: B60303 LDA $0303 F943: F60302 LDB $0302 F946: 1F01 TFR D,X F948: AD84 JSR ,X F94A: 39 RTS ;=============================================================================== ; Track/sector division routine ; F94B: B60303 LDA $0303 ;load logical sector high F94E: F60302 LDB $0302 ;load logical sector low F951: 10A34A CMPD 10,U ;check if over total sector count F954: 2303 BLS $F959 ;jump if <= F956: 1A01 ORCC #$01 ;C=1 for invalid logical sector F958: 39 RTS F959: 7F0314 CLR $0314 ;set track:sector to zero F95C: 10A34D CMPD 13,U ;check if still more than a track F95F: 2307 BLS $F968 ;jump if not F961: A34D SUBD 13,U ;subtract a track's worth of sectors F963: 7C0314 INC $0314 ;increment track number F966: 20F4 BRA $F95C ;next track F968: F70315 STB $0315 ;store physical sector number F96B: AE48 LDX 8,U ;X = sector size F96D: FC0314 LDD $0314 ;load track:sector F970: 10830003 CMPD #$0003 ;check if boot sector F974: 2E03 BGT $F979 ;jump if not F976: 8E0080 LDX #$0080 ;force 128 byte sector F979: BF035D STX $035D ;set sector size F97C: 6F43 CLR 3,U ;select side 1 F97E: B60314 LDA $0314 ;load track number F981: A146 CMPA 6,U ;check if greater than track count F983: 2509 BCS $F98E ;jump if not F985: A046 SUBA 6,U ;subtract track count F987: B70314 STA $0314 ;update physical track number F98A: 8602 LDA #$02 ;choose side 2 F98C: A743 STA 3,U ;select side 2 F98E: 1CFE ANDCC #$FE ;C=0 for valid sector F990: 39 RTS ;=============================================================================== ; Motor on and seek to track ; F991: BDF20C JSR $F20C ;force interrupt FDC F994: 8604 LDA #$04 ;four retries F996: B70308 STA $0308 ;set retry counter F999: B60313 LDA $0313 ;get selected drive index F99C: 8A10 ORA #$10 ;select drive F99E: AA44 ORA 4,U ;merge encoding bit F9A0: B76000 STA $6000 ;write control F9A3: 8610 LDA #$10 ;motor on bit F9A5: BDF290 JSR $F290 ;set drive status bit F9A8: B64000 LDA $4000 ;get FDC status F9AB: 8540 BITA #$40 ;check if write protected F9AD: 2705 BEQ $F9B4 ;jump if not protected F9AF: 8608 LDA #$08 ;write protect failure bit F9B1: BDF290 JSR $F290 ;set drive status bit F9B4: A64C LDA 12,U F9B6: 261C BNE $F9D4 F9B8: BDFC02 JSR $FC02 ;delay F9BB: BDFC02 JSR $FC02 ;delay F9BE: BDFDA2 JSR $FDA2 ;recalibrate drive F9C1: BDFC02 JSR $FC02 ;delay F9C4: 240E BCC $F9D4 F9C6: 7A0308 DEC $0308 ;decrement retry counter F9C9: 10270080 LBEQ $FA4D F9CD: BDF20C JSR $F20C ;force interrupt FDC F9D0: 6F4C CLR 12,U F9D2: 20E0 BRA $F9B4 F9D4: BE030B LDX $030B ;check motor off timer F9D7: 2611 BNE $F9EA ;jump if motor is already running F9D9: BDFC02 JSR $FC02 ;delay for motor spin-up F9DC: BDFC02 JSR $FC02 ;delay F9DF: BDFC02 JSR $FC02 ;delay F9E2: BDFC02 JSR $FC02 ;delay F9E5: B60300 LDA $0300 ;get device ID F9E8: 2000 BRA $F9EA F9EA: B7035B STA $035B ; F9ED: BDFA74 JSR $FA74 ;detect density F9F0: 108EAFFF LDY #$AFFF F9F4: 10BF030B STY $030B ;set motor off timer F9F8: 8EFA33 LDX #$FA33 F9FB: BF035F STX $035F ;set NMI handler F9FE: 10FF0361 STS $0361 FA02: A647 LDA 7,U ;get current track for drive FA04: B74001 STA $4001 ;set current track on FDC FA07: 7D0369 TST $0369 FA0A: 2605 BNE $FA11 FA0C: B10314 CMPA $0314 ;check if we're already on correct track FA0F: 2747 BEQ $FA58 ;jump if so FA11: 7F0369 CLR $0369 FA14: B60314 LDA $0314 ;get requested track FA17: B74003 STA $4003 ;set FDC desired track FA1A: A747 STA 7,U ;set current track in DCB FA1C: 861C LDA #$1C ;FDC seek command FA1E: AA42 ORA 2,U ;merge in step rate FA20: B74000 STA $4000 ;write FDC command FA23: BDFBFA JSR $FBFA ;short delay FA26: B6C000 LDA $C000 FA29: BDFDCF JSR $FDCF ;wait for FDC idle FA2C: B64000 LDA $4000 ;get drive status FA2F: 8510 BITA #$10 ;check for RNF FA31: 2728 BEQ $FA5B ;jump if not FA33: B60356 LDA $0356 FA36: 2703 BEQ $FA3B FA38: BDF2FC JSR $F2FC ;toggle density FA3B: 7A0308 DEC $0308 FA3E: 270D BEQ $FA4D FA40: BDF20C JSR $F20C ;force interrupt FDC FA43: 7F035F CLR $035F FA46: 6F4C CLR 12,U FA48: BDFDA2 JSR $FDA2 ;recalibrate drive FA4B: 20A0 BRA $F9ED FA4D: 6F4C CLR 12,U FA4F: B64000 LDA $4000 ;get FDC status FA52: 8A10 ORA #$10 ;pretend RNF status FA54: 1A01 ORCC #$01 ;set C=1 error FA56: 2005 BRA $FA5D FA58: B64000 LDA $4000 ;get FDC status FA5B: 1CFE ANDCC #$FE ;set C=0 success FA5D: A741 STA 1,U ;store in DCB FA5F: 8600 LDA #$00 FA61: B7035F STA $035F FA64: B60313 LDA $0313 ;get selected drive index FA67: 8A10 ORA #$10 ;motor/drive on FA69: AA44 ORA 4,U ;merge in density flag FA6B: 8A40 ORA #$40 ;?? FA6D: B76000 STA $6000 ;write control FA70: B70365 STA $0365 FA73: 39 RTS ;=============================================================================== ; Detect density ; FA74: B60301 LDA $0301 ;get command ID FA77: 8152 CMPA #$52 ;check if read sector FA79: 2651 BNE $FACC ;jump if not FA7B: FC0302 LDD $0302 ;get sector number FA7E: 10830100 CMPD #$0100 ;check if logical sector 1 FA82: 2648 BNE $FACC ;exit if not FA84: B60313 LDA $0313 ;get selected drive index FA87: 8A10 ORA #$10 ;motor/drive on FA89: 8A80 ORA #$80 ;set single density FA8B: B76000 STA $6000 ;write control FA8E: B60800 LDA $0800 FA91: C606 LDB #$06 ;six bytes to read for address field FA93: 8E04E4 LDX #$04E4 ;set timeout FA96: 108E036B LDY #$036B ;set sector address buffer FA9A: 86C0 LDA #$C0 ;read address command FA9C: B74000 STA $4000 ;write FDC command FA9F: 301F LEAX -1,X ;decrement timeout counter FAA1: 2716 BEQ $FAB9 ;jump if timeout FAA3: B64000 LDA $4000 ;check FDC status FAA6: 8502 BITA #$02 ;test DRQ FAA8: 27F5 BEQ $FA9F ;keep waiting if not FAAA: B64003 LDA $4003 ;read byte from FDC FAAD: A7A0 STA ,Y+ ;store in sector address buffer FAAF: 5A DECB ;next byte FAB0: 26ED BNE $FA9F ;jump if need more bytes FAB2: B6036C LDA $036C ;get side field FAB5: 8101 CMPA #$01 FAB7: 230E BLS $FAC7 FAB9: 8D32 BSR $FAED ;switch to MFM FABB: B60313 LDA $0313 ;get selected drive index FABE: 8A10 ORA #$10 ;motor/drive on FAC0: AA44 ORA 4,U ;merge density setting FAC2: B76000 STA $6000 ;write control FAC5: 2002 BRA $FAC9 ;force interrupt and exit FAC7: 8D04 BSR $FACD ;select single density FAC9: BDF20C JSR $F20C ;force interrupt FDC FACC: 39 RTS FACD: 8680 LDA #$80 ;FM encoding FACF: A744 STA 4,U FAD1: 8610 LDA #$10 ;motor on FAD3: A7C4 STA ,U ;set drive status FAD5: 8601 LDA #$01 FAD7: A745 STA 5,U FAD9: 8628 LDA #$28 ;40 tracks FADB: A746 STA 6,U FADD: 8E02D0 LDX #$02D0 ;720 sectors total FAE0: AF4A STX 10,U FAE2: 8E0080 LDX #$0080 ;128 bytes per sector FAE5: AF48 STX 8,U FAE7: 8E0012 LDX #$0012 ;18 sectors per track FAEA: AF4D STX 13,U FAEC: 39 RTS ;=============================================================================== FAED: B60356 LDA $0356 FAF0: 2613 BNE $FB05 ;select enhanced density FAF2: 8600 LDA #$00 ;MFM encoding FAF4: A744 STA 4,U ;set FDC status FAF6: 8630 LDA #$30 ;motor on + double density FAF8: A7C4 STA ,U ;set drive status FAFA: 8E0100 LDX #$0100 ;256 bytes per sector FAFD: AF48 STX 8,U FAFF: 8E0012 LDX #$0012 ;18 sectors per track FB02: AF4D STX 13,U FB04: 39 RTS FB05: 8600 LDA #$00 ;MFM encoding FB07: A744 STA 4,U FB09: 8E0400 LDX #$0400 ;1024 sectors total FB0C: AF4A STX 10,U FB0E: 8E001A LDX #$001A ;26 sectors per track FB11: AF4D STX 13,U FB13: 8601 LDA #$01 FB15: A745 STA 5,U FB17: 8610 LDA #$10 ;motor on FB19: A7C4 STA ,U ;set drive status FB1B: 8628 LDA #$28 ;40 tracks FB1D: A746 STA 6,U FB1F: 8E0080 LDX #$0080 ;128 bytes per sector FB22: AF48 STX 8,U FB24: 39 RTS ;=============================================================================== ; Printer get status command handler ($53) ; FB25: BDFC7A JSR $FC7A ;send ACK + Complete FB28: 8E0357 LDX #$0357 FB2B: 108E0004 LDY #$0004 FB2F: BDF280 JSR $F280 ;send frame FB32: 86FF LDA #$FF FB34: B70358 STA $0358 FB37: 8680 LDA #$80 FB39: B70357 STA $0357 FB3C: 39 RTS ;=============================================================================== ; Printer write command handler ($57) ; FB3D: 8680 LDA #$80 FB3F: B70357 STA $0357 FB42: 864E LDA #$4E FB44: B70358 STA $0358 FB47: BDFC6A JSR $FC6A ;delay + send ACK FB4A: 8E0000 LDX #$0000 FB4D: 108E0028 LDY #$0028 FB51: BDF16A JSR $F16A ;receive data frame FB54: 2407 BCC $FB5D FB56: BDFBFA JSR $FBFA ;short delay FB59: BDFC7F JSR $FC7F ;send NAK FB5C: 39 RTS FB5D: BDFC6A JSR $FC6A ;delay + send ACK FB60: 108E0000 LDY #$0000 FB64: 8E5B00 LDX #$5B00 FB67: F60359 LDB $0359 FB6A: F70308 STB $0308 FB6D: C628 LDB #$28 ;40 characters max to print FB6F: A6A0 LDA ,Y+ ;get next character from buffer FB71: 3402 PSHS A ;save ATASCII character FB73: 819B CMPA #$9B ;check if EOL FB75: 2602 BNE $FB79 ;skip if not FB77: 860D LDA #$0D ;replace EOL with CR FB79: 3402 PSHS A ;save ASCII character FB7B: 3410 PSHS X ; FB7D: BE030B LDX $030B FB80: 270A BEQ $FB8C FB82: 301F LEAX -1,X FB84: BF030B STX $030B FB87: 2603 BNE $FB8C FB89: 7F0365 CLR $0365 FB8C: 3510 PULS X FB8E: 301F LEAX -1,X FB90: 2608 BNE $FB9A FB92: 8E5B00 LDX #$5B00 FB95: 7A0308 DEC $0308 ;decrement timeout hi FB98: 2734 BEQ $FBCE ;jump if timeout FB9A: B61000 LDA $1000 ;read status port FB9D: 8580 BITA #$80 ;check if printer ready FB9F: 26DA BNE $FB7B ;keep waiting if not FBA1: 3502 PULS A ;restore ASCII character FBA3: B71800 STA $1800 ;set character to parallel port FBA6: 3470 PSHS X,Y,U FBA8: 3570 PULS U,Y,X FBAA: B60365 LDA $0365 ;get control shadow FBAD: 8A20 ORA #$20 ;set strobe bit FBAF: B76000 STA $6000 ;assert printer strobe FBB2: 12 NOP ;tiny delay FBB3: 12 NOP ; " FBB4: 84DF ANDA #$DF ;reset strobe bit FBB6: B76000 STA $6000 ;deassert printer strobe FBB9: 3502 PULS A ;restore ATASCII character FBBB: 819B CMPA #$9B ;was it EOL? FBBD: 271A BEQ $FBD9 ;exit if so FBBF: 5A DECB ;decrement char count FBC0: 2717 BEQ $FBD9 ;exit if out of chars FBC2: 3410 PSHS X ;save buffer index FBC4: 8E0005 LDX #$0005 ;set delay FBC7: BDFBFD JSR $FBFD ;delay FBCA: 3510 PULS X ;restore buffer index FBCC: 20A1 BRA $FB6F ;loop back for next char FBCE: 3506 PULS B,A ;clean up stack FBD0: 8604 LDA #$04 ;unsuccessful put operation FBD2: BDF290 JSR $F290 ;set device status bit FBD5: BDFC7F JSR $FC7F ;send NAK FBD8: 39 RTS FBD9: CC0000 LDD #$0000 ;zero print buffer FBDC: 8E0000 LDX #$0000 FBDF: ED81 STD ,X++ FBE1: 8C0028 CMPX #$0028 FBE4: 23F9 BLS $FBDF FBE6: BDFC72 JSR $FC72 ;delay + send Complete FBE9: 39 RTS ;=============================================================================== ; Set printer timeout command handler ($65) ; FBEA: BDFC6D JSR $FC6D ;send ACK FBED: BDFC3D JSR $FC3D ;read byte and update checksum FBF0: B70359 STA $0359 FBF3: BDFC3D JSR $FC3D ;read byte and update checksum FBF6: BDFC7A JSR $FC7A ;send ACK + Complete FBF9: 39 RTS ;=============================================================================== ; Delay (~140 cycles) ; FBFA: 8E0010 LDX #$0010 ;3 FBFD: 301F LEAX -1,X ;5 FBFF: 26FC BNE $FBFD ;3 FC01: 39 RTS ;5 ;=============================================================================== ; Delay (~125K cycles) ; FC02: 8E3D09 LDX #$3D09 FC05: 20F6 BRA $FBFD ;=============================================================================== ; Wait for command line to deassert ; FC07: B62000 LDA $2000 FC0A: 8508 BITA #$08 FC0C: 26F9 BNE $FC07 FC0E: 39 RTS ;=============================================================================== ; Receive command frame ; FC0F: 8E0300 LDX #$0300 FC12: 108E0004 LDY #$0004 FC16: 5F CLRB FC17: 1CFE ANDCC #$FE FC19: 8D17 BSR $FC32 ;receive data frame FC1B: F70305 STB $0305 ;store computed checksum FC1E: 8D1D BSR $FC3D ;receive checksum byte FC20: B70304 STA $0304 ;store received checksum FC23: 8DE2 BSR $FC07 ;wait for command to deassert FC25: 1CFE ANDCC #$FE ;C=0 FC27: B60304 LDA $0304 ;get received checksum FC2A: B10305 CMPA $0305 ;compare to computed checksum FC2D: 2702 BEQ $FC31 ;exit C=0 if checksum OK FC2F: 1A01 ORCC #$01 ;exit C=1 if checksum bad FC31: 39 RTS ;=============================================================================== ; Receive data frame ; FC32: 8D09 BSR $FC3D ;receive byte and update checksum FC34: A780 STA ,X+ ;store in buffer FC36: 313F LEAY -1,Y ;decrement count FC38: 26F8 BNE $FC32 ;loop if not done yet FC3A: C900 ADCB #$00 ;finalize checksum FC3C: 39 RTS ;=============================================================================== ; Receive byte and update checksum ; FC3D: B62000 LDA $2000 ;read ACIA status FC40: 8501 BITA #$01 ;check if byte received FC42: 27F9 BEQ $FC3D ;wait if not FC44: B62001 LDA $2001 ;get received byte FC47: 3402 PSHS A FC49: E9E4 ADCB ,S ;update checksum FC4B: 3502 PULS A FC4D: 39 RTS ;=============================================================================== ; Send data frame ; FC4E: A680 LDA ,X+ FC50: 8D07 BSR $FC59 ;send byte FC52: 313F LEAY -1,Y FC54: 26F8 BNE $FC4E FC56: C900 ADCB #$00 ;finalize checksum FC58: 39 RTS ;=============================================================================== ; Send byte and update checksum ; FC59: 3402 PSHS A FC5B: B62000 LDA $2000 ;get ACIA status FC5E: 8502 BITA #$02 ;check if transmit empty FC60: 27F9 BEQ $FC5B ;loop if not FC62: E9E4 ADCB ,S ;update checksum FC64: 3502 PULS A FC66: B72001 STA $2001 ;write byte to transmit FC69: 39 RTS ;=============================================================================== ; Send ACK ; FC6A: BDFBFA JSR $FBFA ;short delay FC6D: 8641 LDA #$41 ;ACK FC6F: 8DE8 BSR $FC59 ;send byte FC71: 39 RTS ;=============================================================================== ; Send Complete ; FC72: BDFBFA JSR $FBFA ;short delay FC75: 8643 LDA #$43 ;Complete FC77: 8DE0 BSR $FC59 ;send byte FC79: 39 RTS ;=============================================================================== ; Send ACK + Complete ; FC7A: 8DEE BSR $FC6A ;delay + send ACK FC7C: 8DF4 BSR $FC72 ;delay + send Complete FC7E: 39 RTS ;=============================================================================== ; Send NAK ; FC7F: 864E LDA #$4E ;NAK FC81: 8DD6 BSR $FC59 ;send byte FC83: 39 RTS ;=============================================================================== ; Send Error ; FC84: 8645 LDA #$45 ;Error FC86: 8DD1 BSR $FC59 ;send byte FC88: 39 RTS ;=============================================================================== ; Power-on initialization ; FC89: 8E0000 LDX #$0000 ;clear RAM $0000-039F FC8C: CC0000 LDD #$0000 FC8F: ED81 STD ,X++ FC91: 8C039F CMPX #$039F FC94: 25F9 BCS $FC8F FC96: 8601 LDA #$01 ;assume two internal drives FC98: F61000 LDB $1000 ;read status port FC9B: C520 BITB #$20 ;check for internal drive 2 FC9D: 2601 BNE $FCA0 ;skip if present FC9F: 4A DECA ;only one internal drive FCA0: B7036B STA $036B ;set number of internal drives FCA3: 7F0366 CLR $0366 FCA6: B68001 LDA $8001 ;read switches FCA9: 43 COMA ;uninvert FCAA: 8403 ANDA #$03 ;mask to starting drive number switches FCAC: 8B31 ADDA #$31 ;map to device ID FCAE: B7035C STA $035C ;set starting device ID FCB1: B68001 LDA $8001 ;read switches FCB4: 5F CLRB ;start with drive 0 (externals will be 3/4) FCB5: 8404 ANDA #$04 ;check switch 7 (external drive ID) FCB7: 2702 BEQ $FCBB ;skip if on FCB9: C602 LDB #$02 ;start with drive 2 (externals will be 1/2) FCBB: 3404 PSHS B FCBD: 108E0004 LDY #$0004 ;4 drives to process FCC1: A6E4 LDA ,S ;get drive index FCC3: 8A10 ORA #$10 ;motor/drive on FCC5: B76000 STA $6000 ;write control FCC8: BDFC02 JSR $FC02 ;delay FCCB: BDFC02 JSR $FC02 ;delay FCCE: CE0316 LDU #$0316 FCD1: E6E4 LDB ,S FCD3: C403 ANDB #$03 FCD5: 58 ASLB FCD6: 58 ASLB FCD7: 58 ASLB FCD8: 58 ASLB FCD9: 33C5 LEAU B,U FCDB: BDFD8E JSR $FD8E ;check if drive present FCDE: 2578 BCS $FD58 ;skip init/assign drive if not present FCE0: B61000 LDA $1000 ;load status port FCE3: 8510 BITA #$10 ;check test switch FCE5: 261F BNE $FD06 ;jump if not on FCE7: B68000 LDA $8000 ;read switches FCEA: 840F ANDA #$0F ;isolate to per-drive density switches FCEC: 2605 BNE $FCF3 ;skip if any off (any double density) FCEE: 7C036A INC $036A FCF1: 2009 BRA $FCFC FCF3: 810F CMPA #$0F ;check if all off (all double density) FCF5: 2705 BEQ $FCFC ;jump if so FCF7: 7C036A INC $036A FCFA: 200A BRA $FD06 FCFC: 8E0080 LDX #$0080 ;128 bytes per sector FCFF: AF48 STX 8,U ;set sector size FD01: 7C0356 INC $0356 FD04: 201A BRA $FD20 FD06: 8E0100 LDX #$0100 ;256 bytes per sector FD09: F60366 LDB $0366 FD0C: 3420 PSHS Y FD0E: 108EFD8A LDY #$FD8A ;Drive bit table FD12: B68000 LDA $8000 FD15: A5A5 BITA B,Y ;check default density switch for drive FD17: 2603 BNE $FD1C FD19: 8E0080 LDX #$0080 ;128 bytes per sector FD1C: AF48 STX 8,U ;set drive sector size FD1E: 3520 PULS Y FD20: 1F10 TFR X,D ;get low byte of sector size FD22: C480 ANDB #$80 ;convert to FM/MFM encoding FD24: E744 STB 4,U ;set encoding FD26: 8620 LDA #$20 ;double density flag FD28: C580 BITB #$80 ;check if single density FD2A: 2702 BEQ $FD2E ;skip if so FD2C: 8610 LDA #$10 ;motor on FD2E: A7C4 STA ,U ;set drive status FD30: 8600 LDA #$00 ;clear FDC status FD32: A741 STA 1,U FD34: 8601 LDA #$01 ;set single sided FD36: A745 STA 5,U FD38: 8628 LDA #$28 ;set 40 tracks FD3A: A746 STA 6,U FD3C: 8E02D0 LDX #$02D0 ;set 720 total sectors FD3F: AF4A STX 10,U FD41: 8E0012 LDX #$0012 ;set 18 sectors per track FD44: AF4D STX 13,U FD46: 8E030F LDX #$030F ;point to drive device ID table FD49: E6E4 LDB ,S ;load drive index FD4B: C403 ANDB #$03 ;mask to 0-3 FD4D: B6035C LDA $035C ;load current device ID FD50: A785 STA B,X ;set device ID for drive FD52: 7C035C INC $035C ;next device ID FD55: 7C0366 INC $0366 FD58: 6CE4 INC ,S FD5A: 313F LEAY -1,Y FD5C: 1026FF6E LBNE $FCCE ;next drive FD60: 861E LDA #$1E FD62: B70359 STA $0359 ;set printer timeout FD65: 8680 LDA #$80 FD67: B70357 STA $0357 ;set printer status FD6A: 8678 LDA #$78 FD6C: B70306 STA $0306 ;set format timeout FD6F: 3504 PULS B FD71: 86D0 LDA #$D0 ;force interrupt command FD73: B74000 STA $4000 ;write FDC command FD76: 7F6000 CLR $6000 ;deselect drives FD79: 8603 LDA #$03 ;reset ACIA FD7B: B72000 STA $2000 ;write ACIA control FD7E: 8615 LDA #$15 ;/RTS low, disable xmit IRQ, 8d1sb, /16 FD80: B72000 STA $2000 ;write ACIA control FD83: 73035B COM $035B FD86: B62001 LDA $2001 ;clear receive register FD89: 39 RTS ;=============================================================================== ; Drive bit table ; FD8A: 01020408 ;=============================================================================== ; Check if drive present / recalibrate ; FD8E: A662 LDA 2,S ;get drive index FD90: 8403 ANDA #$03 FD92: B1036B CMPA $036B ;check if it's one of the internal drives FD95: 2331 BLS $FDC8 ;skip test if so FD97: 8A10 ORA #$10 ;drive/motor on FD99: B76000 STA $6000 ;select drive FD9C: BDFC02 JSR $FC02 ;delay FD9F: BDFC02 JSR $FC02 ;delay FDA2: C600 LDB #$00 ;recalibrate command FDA4: EA42 ORB 2,U ;merge in step rate FDA6: F74000 STB $4000 ;write FDC command FDA9: E642 LDB 2,U FDAB: 8EFDCB LDX #$FDCB FDAE: E685 LDB B,X FDB0: 8E7FFF LDX #$7FFF FDB3: B64000 LDA $4000 ;get FDC status FDB6: 8504 BITA #$04 ;check for track 0 FDB8: 260A BNE $FDC4 ;jump if track 0 found FDBA: 301F LEAX -1,X ;decrement timeout lo FDBC: 26F5 BNE $FDB3 ;jump if no underflow yet FDBE: 5A DECB ;decrement timeout hi FDBF: 26EF BNE $FDB0 ;jump if no timeout yet FDC1: 1A01 ORCC #$01 ;C=1 drive not found FDC3: 39 RTS FDC4: 6F47 CLR 7,U ;set current track to 0 FDC6: 6C4C INC 12,U FDC8: 1CFE ANDCC #$FE ;C=0 drive found FDCA: 39 RTS ;=============================================================================== FDCB: 01 02 04 06 ;=============================================================================== ; Wait for FDC idle ; FDCF: B64000 LDA $4000 FDD2: 8501 BITA #$01 FDD4: 26F9 BNE $FDCF FDD6: 39 RTS ;=============================================================================== ; Wait for FDC busy ; FDD7: B64000 LDA $4000 ;read FDC status FDDA: 8501 BITA #$01 ;check BSY FDDC: 27F9 BEQ $FDD7 ;keep looping if not BSY yet FDDE: 39 RTS ;=============================================================================== ; NMI handler ; FDDF: 7D035F TST $035F ;check if exception handler set FDE2: 2601 BNE $FDE5 ;jump if so FDE4: 3B RTI ;nope, ignore the NMI FDE5: 1CEF ANDCC #$EF ;enable IRQs FDE7: 10FE0361 LDS $0361 ;restore stack pointer FDEB: 6E9F JMP [$035F] ;jump to exception handler ;=============================================================================== ; IRQ handler ; FDEF: 7F035F CLR $035F ;clear exception handler FDF2: B60800 LDA $0800 FDF5: 7F0363 CLR $0363 FDF8: 7F0364 CLR $0364 ;clear custom interleave flag FDFB: C600 LDB #$00 FDFD: 8E030F LDX #$030F ;drive device ID table pointer FE00: CE0316 LDU #$0316 ;DCB table pointer FE03: A685 LDA B,X ;read device ID for drive FE05: 270E BEQ $FE15 FE07: 8131 CMPA #$31 ;check if D1: FE09: 2602 BNE $FE0D FE0B: 6F4C CLR 12,U FE0D: A6C4 LDA ,U ;get drive status FE0F: 8470 ANDA #$70 ;turn off wp, bad put, c/d frame errors FE11: A7C4 STA ,U FE13: 6F41 CLR 1,U ;clear FDC status FE15: 33C810 LEAU 16,U ;next DCB FE18: 5C INCB ;next drive FE19: C104 CMPB #$04 ;check if all four drives checked FE1B: 26E6 BNE $FE03 ;loop back if not FE1D: 8615 LDA #$15 ;reset ACIA to 19200 baud FE1F: B72000 STA $2000 ;write ACIA control FE22: 10CE03FF LDS #$03FF ;reset stack pointer FE26: 7EF00F JMP $F00F ;jump back to main loop ;=============================================================================== ; Disk drive command table ; FE29: 58 F90B ;$58 Write memory FE2C: 59 F92A ;$59 Read memory FE2F: 5A F940 ;$5A Execute FE32: 53 F0D2 ;$53 Get status FE35: 57 F101 ;$57 Write sector FE38: 52 F21C ;$52 Read sector FE3B: 72 F21C ;$72 High speed read sector FE3E: 77 F101 ;$77 High speed write sector FE41: 70 F101 ;$70 High speed put sector FE44: 21 F32D ;$21 Format FE47: 50 F101 ;$50 Put sector FE4A: 22 F3E7 ;$22 Format medium FE4D: 74 F3E7 ;$74 Set medium density FE50: 75 F7D8 ;$75 Set single density FE53: 76 F7E2 ;$76 Set double density FE56: 4E F65B ;$4E Read PERCOM block FE59: 4F F6AC ;$4F Write PERCOM block FE5C: 66 F3C7 ;$66 Set interleave (NOT format skewed) FE5F: 78 F745 ;$78 Reset FE62: 63 F70D ;$63 Get drive device IDs FE65: 64 F71E ;$64 Set drive device IDs FE68: 69 F74F ;$69 Get drive count FE6B: 43 F776 ;$43 Check disk FE6E: 56 F7FB ;$56 Get version FE71: 6D FE85 ;$6D Get Easter egg FE74: 73 F825 ;$73 Read switches FE77: 71 F857 ;$71 Get drive speed FE7A: 00 ;=============================================================================== ; Printer command table ; FE7B: 53 FB25 ;$53 Get status FE7E: 57 FB3D ;$57 Write FE80: 65 FBEA ;$65 Set printer timeout FE84: 00 ;=============================================================================== ; Get Easter egg command ($6D) ; FE85: BDFC7A JSR $FC7A ;send ACK + Complete FE88: BDFBFA JSR $FBFA ;short delay FE8B: 8EFE96 LDX #$FE96 ;message pointer FE8E: 108E0019 LDY #$0019 ;message length FE92: BDF280 JSR $F280 ;send frame FE95: 39 RTS FE96: 2052424D20 ' RBM ' FE9B: 31302F32372F3833 '10/27/83' FEA3: 20204849204D4F4D ' HI MOM' FEAB: 21212121 '!!!!' ;=============================================================================== ; Reset handler ; FEAF: 1A50 ORCC #$50 FEB1: B61000 LDA $1000 ;load status port FEB4: 8510 BITA #$10 ;check if test switch on FEB6: 1026F146 LBNE $F000 ;begin normal init if not FEBA: B68000 LDA $8000 ;get SW1-4 FEBD: 8508 BITA #$08 ;check if SW3 is on FEBF: 1027F13D LBEQ $F000 ;begin normal init if so FEC3: F68000 LDB $8000 ;get SW1-4 FEC6: C407 ANDB #$07 ;mask to SW1-3 FEC8: 8EFED2 LDX #$FED2 ;load test routine table FECB: 58 ASLB ;2x FECC: 3A ABX ;indexing FECD: 10AE84 LDY ,X ;load test routine pointer FED0: 6EA4 JMP ,Y ;run test routine ;=============================================================================== ; SW0-2 -> test ; FED2: FEE2 ;111 FED4: FF08 ;110 FED6: FF29 ;101 FED8: FF3A ;100 FEDA: FEAF ;011 Nothing FEDC: FEAF ;010 Nothing FEDE: FEAF ;001 Nothing FEE0: F000 ;000 Normal operation ;=============================================================================== ; Test mode 7 (SIO transmit test) ; FEE2: 7F6000 CLR $6000 FEE5: 8603 LDA #$03 FEE7: B72000 STA $2000 FEEA: 8615 LDA #$15 FEEC: B72000 STA $2000 FEEF: B62000 LDA $2000 FEF2: B62001 LDA $2001 FEF5: 4F CLRA FEF6: F60800 LDB $0800 FEF9: F62000 LDB $2000 ;load ACIA status FEFC: C502 BITB #$02 ;check for transmit empty FEFE: 27F9 BEQ $FEF9 ;loop if not FF00: B72001 STA $2001 ;write byte to SIO FF03: 4C INCA ;increment test byte FF04: 27F0 BEQ $FEF6 FF06: 20F1 BRA $FEF9 ;=============================================================================== ; Test mode 6 ; FF08: 8E0000 LDX #$0000 FF0B: 865A LDA #$5A FF0D: A784 STA ,X FF0F: E680 LDB ,X+ FF11: 8C0402 CMPX #$0402 FF14: 26F7 BNE $FF0D FF16: 8E0000 LDX #$0000 FF19: 86A5 LDA #$A5 FF1B: A784 STA ,X FF1D: E680 LDB ,X+ FF1F: 8C0402 CMPX #$0402 FF22: 26F7 BNE $FF1B FF24: B60800 LDA $0800 FF27: 20DF BRA $FF08 ;=============================================================================== ; Test mode 5 ; FF29: 8EF000 LDX #$F000 FF2C: 8C0000 CMPX #$0000 FF2F: 2704 BEQ $FF35 FF31: A680 LDA ,X+ FF33: 20F7 BRA $FF2C FF35: B60800 LDA $0800 FF38: 20EF BRA $FF29 ;=============================================================================== ; Test mode 4 ; FF3A: 8600 LDA #$00 FF3C: B71800 STA $1800 ;write to printer port FF3F: 8A10 ORA #$10 FF41: B76000 STA $6000 FF44: 4C INCA FF45: 26F5 BNE $FF3C FF47: B60800 LDA $0800 FF4A: 20EE BRA $FF3A ;=============================================================================== FF4C: 0000 NEG $00 FF4E: 0000 NEG $00 FF50: 0000 NEG $00 FF52: 0000 NEG $00 FF54: 0000 NEG $00 FF56: 0000 NEG $00 FF58: 0000 NEG $00 FF5A: 0000 NEG $00 FF5C: 0000 NEG $00 FF5E: 0000 NEG $00 FF60: 0000 NEG $00 FF62: 0000 NEG $00 FF64: 0000 NEG $00 FF66: 0000 NEG $00 FF68: 0000 NEG $00 FF6A: 0000 NEG $00 FF6C: 0000 NEG $00 FF6E: 0000 NEG $00 FF70: 0000 NEG $00 FF72: 0000 NEG $00 FF74: 0000 NEG $00 FF76: 0000 NEG $00 FF78: 0000 NEG $00 FF7A: 0000 NEG $00 FF7C: 0000 NEG $00 FF7E: 0000 NEG $00 FF80: 0000 NEG $00 FF82: 0000 NEG $00 FF84: 0000 NEG $00 FF86: 0000 NEG $00 FF88: 0000 NEG $00 FF8A: 0000 NEG $00 FF8C: 0000 NEG $00 FF8E: 0000 NEG $00 FF90: 0000 NEG $00 FF92: 0000 NEG $00 FF94: 0000 NEG $00 FF96: 0000 NEG $00 FF98: 0000 NEG $00 FF9A: 0000 NEG $00 FF9C: 0000 NEG $00 FF9E: 0000 NEG $00 FFA0: 0000 NEG $00 FFA2: 0000 NEG $00 FFA4: 0000 NEG $00 FFA6: 0000 NEG $00 FFA8: 0000 NEG $00 FFAA: 0000 NEG $00 FFAC: 0000 NEG $00 FFAE: 0000 NEG $00 FFB0: 0000 NEG $00 FFB2: 0000 NEG $00 FFB4: 0000 NEG $00 FFB6: 0000 NEG $00 FFB8: 0000 NEG $00 FFBA: 0000 NEG $00 FFBC: 0000 NEG $00 FFBE: 0000 NEG $00 FFC0: 0000 NEG $00 FFC2: 0000 NEG $00 FFC4: 0000 NEG $00 FFC6: 0000 NEG $00 FFC8: 0000 NEG $00 FFCA: 0000 NEG $00 FFCC: 0000 NEG $00 FFCE: 0000 NEG $00 FFD0: 0000 NEG $00 FFD2: 0000 NEG $00 FFD4: 0000 NEG $00 FFD6: 0000 NEG $00 FFD8: 0000 NEG $00 FFDA: 0000 NEG $00 FFDC: 0000 NEG $00 FFDE: 0000 NEG $00 FFE0: 0000 NEG $00 FFE2: 0000 NEG $00 FFE4: 0000 NEG $00 FFE6: 0000 NEG $00 FFE8: 0000 NEG $00 FFEA: 0000 NEG $00 FFEC: 0000 NEG $00 FFEE: 0000 NEG $00 FFF0: 0000 NEG $00 FFF2: 0000 NEG $00 FFF4: 0000 NEG $00 FFF6: F000 ;FIRQ FFF8: FDEF ;IRQ FFFA: F000 ;SWI FFFC: FDDF ;NMI FFFE: FEAF ;Reset