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*
** FLEX 9 DISK DRIVERS
*
* FOR SYS09BUG ON THE DIGILENT SPARTAN 3 STARTER BOARD
* WITH I/O MAPPED AT $XE000
* AND ROM MAPPED AT $XF000
* THE DIGILENT SPARTAN 3 STARTER BOARD HAS 1MBYTE OF SRAM
* THE FIRST 64K IS USED BY FLEX,
* THE SECOND 128K IS USED AS A ROM DISK
* THE REMAINING RAM IS USED FOR A RAM DISK
*
*
CFLAG   EQU $01     CARRY FLAG
VFLAG   EQU $02     OVERFLOW FLAG
ZFLAG   EQU $04     ZERO FLAG
NFLAG   EQU $08     NEGATIVE FLAG
IFLAG   EQU $10     IRQ MASK CC
HFLAG   EQU $20     HALF CARRY
FFLAG   EQU $40     FIRQ MASK CC
EFLAG   EQU $80     ENTIRE FLAG
*
MAPPAG  EQU $00     PAGE $0000 DAT ADDRESS
DATREG  EQU IC11    DAT REGISTERS
*
* Serial Port
*
ACIAC1  EQU ACIAS
ACIAD1  EQU ACIAS+1
DELCON  EQU 1250    Delay (Processor clock in MHz * 50)
*
* XMODEM Control characters
*
SOH     EQU $01
EOT     EQU $04
ACK     EQU $06
NAK     EQU $15
CAN     EQU $18
*
* DRIVE GEOMETRY
*
EMAXSEC EQU 14     ROM DISK
EMAXTRK EQU 48     3  * 16 * 14 * 256 = 172,032 Bytes
ETOTSEC EQU EMAXTRK*EMAXSEC-EMAXSEC
*
RMAXSEC EQU 14     RAM DISK
RMAXTRK EQU 192    12 * 16 * 14 * 256 = 688,128 Bytes
RTOTSEC EQU RMAXTRK*RMAXSEC-RMAXSEC
*
* DRIVE TYPES
*
DTYPROM EQU 0      ROM DISK
DTYPRAM EQU 1      RAM DISK
DTYPFLS EQU 2      FLASH DISK
DTYPNET EQU 3      FLEXNET DISK
*
       ORG   $DE00
*  
* DISK DRIVER JUMP TABLE LAST UPDATE: 22/12/2006
* Disk driver for RAM Disk.
*
* 14 SECTORS PER TRACK
* 16 * N TRACKS PER DISK
*
* ROM DISK OCCUPIES $10000 - $1E000 ... $30000 - $3E000
* RAM DISK OCCUPIES $40000 - $4E000 ... $F0000 - $FE000
* Track Buffer page mapped at $E000 - $EFFF
* MAPPAG = $00 = 0 x $1000 (4 K pages)

* ON SWTPC ROM AT $XF000 AND IO AT $XE000
* APPEARS THROUGHOUT THE MEMORY SO MUST BE SKIPPED OVER
* WHEN USING RAM AS A RAMDISK.
* THE MSN OF THE TRACK MAPS INTO THE MSN OF THE DAT
* THE LSN OF THE TRACK NUMBER INDEXES INTO THE 4K RAM PAGE
* THE SECTOR MAPS INTO THE LSN OF THE DAT WHICH IS INVERTED
*
*
*
* FLEX disk jump table.
*
READ   JMP   READSC
WRITE  JMP   WRITSC
VERIFY JMP   BUSY
RESTOR JMP   RESTR1
DRIVE  JMP   DRVSEL
DRVRDY JMP   CHKRDY
QUICK  JMP   CHKQIK
COLDDR JMP   DINIT
WARMDR JMP   DWARM
SEEK   JMP   SEEKTS
*
* RAM SPACE
*
DRVNUM  FCB  0
TRACK   FCB  0
SECTOR  FCB  0
CHKSUM  FCB  0
CCSAVE  FCB  0
BLKNUM  FCB  0 Xmodem block number
BYTCNT  FCB  0 Xmodem byte count
XSTATE  FDB  0 Xmodem State Vector
DELCNT  FCB  $00,$00,$00 Xmodem Poll timer
*
* Disc driver type table.
* Indexed by drive number
*
DTYPTAB FCB  DTYPROM Drive 0 (ROM Disk)
        FCB  DTYPRAM Drive 1 (RAM Disk)
        FCB  DTYPFLS Drive 2 (FLASH Disk)
        FCB  DTYPNET Drive 3 (NETPC Disk)
*
* RAM Disk offset
* Indexed by drive type
*
DOFFTAB FCB  $10 ROM Disk $10000
        FCB  $40 RAM DISK $40000
        FCB  $FF Flash Disk
        FCB  $FF NETPC Disk
*
REAVEC  RMB  2             Disc driver jump table.
WRIVEC  RMB  2
VERVEC  RMB  2
RSTVEC  RMB  2
DRVVEC  RMB  2
CHKVEC  RMB  2
QUIVEC  RMB  2
INIVEC  RMB  2
WARVEC  RMB  2
SEEVEC  RMB  2
*
* SECTOR BUFFER
*
BUFFER  RMB  256
SYNCREG RMB  4      Prom input register
*
****************************************
*
* START OF EXTENSION COMMANDS
*
****************************************
*
        ORG MONEXT
        FDB NEXTEXT   Jump to next extended command
*
*
*****************************************
* Disk drivers                          *
* ------------                          *
* The system dependant code for the     *
* disc drivers fits here. Two tables    *
* must be included. These are DTYPTAB a  *
* four byte table that defines which of *
* the (up to four) following sets of    *
* jump tables to use, and TABSRT the    *
* jump tables themselves. For a full    *
* description of the floppy drivers see *
* section 4 (pp9-14) of the general     *
* Flex adaptation guide.                *
*****************************************
*
* Mass storage drivers for embedded applications.
*
* Jump tables.
TABSRT  FDB EREAD Drive type 0 (ROM disk).
        FDB EWRITE
        FDB ECHECK
        FDB ECHECK
        FDB ECHECK
        FDB ECHECK
        FDB ECHECK
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
*
        FDB EREAD Drive type 1 (RAM disk).
        FDB EWRITE
        FDB ECHECK
        FDB ECHECK
        FDB ECHECK
        FDB ECHECK
        FDB ECHECK
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
*
        FDB DDUMMY Drive type 2 (External Flash disk).
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
*
        FDB NREAD  Drive type 3 (NetPC drive via serial port).
        FDB NWRITE
        FDB NVERIFY
        FDB NCHECK
        FDB NCHECK
        FDB NCHECK
        FDB NCHECK
        FDB DDUMMY
        FDB DDUMMY
        FDB DDUMMY
*
*
* Dummy routine (no errors).
DDUMMY  CLRB
        TSTB  Set (z)=1
        ANDCC  #$FF-CFLAG  Set (c)=0
        RTS
*               *
**************************
* Main Flex entry points *
*************************
*
* Read sector routine.
* Entry: (X) = address where sector is to be placed.
*        (A) = Track  number.
*        (B) = Sector number.
* Exit:  (B) = Error code  (z)=1 if no error.
READSC  JMP  [REAVEC]
*
* Write track routine.
* Entry: (X) = Address of area of memory from which the data will be taken.
*        (A) = Track number.
*        (B) = Sector number.
* Exit:  (B) = Error condition, (Z)=1 no an error.
WRITSC  JMP  [WRIVEC]
*
* Verify sector routine.
* Entry: no parameters.
* Exit:  (B) = Error condition (Z)=1 if no error.
BUSY  JMP  [VERVEC]
*
* Restore drive to track 00.
* Entry: (X) = FCB address (3,X contains drive number).
* Exit:  (B) = Error condition, (Z)=1 if no error.
RESTR1  BSR  DRVSEL Select drive first.
        BEQ  RST1
        RTS
RST1    JMP  [RSTVEC]
*
* Select current drive.
* Entry: (X) = FCB address (3,X contains drive number).
* Exit:  (B) = Error condition, (Z)=0 and (c)=1 if error.
*        (B) = $0F if non existant drive.
DRVSEL  PSHS  X,Y
        LDB  3,X  Get driver type.
        STB  DRVNUM
        LDX  #DTYPTAB
        LDA  B,X
        CMPA  #$FF  Is the drive nonexistant?
        BNE  DRIVE1
        PULS  X,Y
        LDB  #$0F
        TSTB
        ORCC  #$01
        RTS
*
DRIVE1  LDB  #20  Get correct table start address.
        MUL
        LDX  #TABSRT
        LEAX  D,X
        LDY  #REAVEC Copy table into ram.
        LDB  #20
DRIVE2  LDA  0,X+
        STA  0,Y+
        DECB
        BNE  DRIVE2
        PULS X,Y
        JMP  [DRVVEC]
*
* Check for drive ready.
* Entry: (X) = FCB address (3,X contains drive number)>
* Exit:  (B) = Error condition, (Z)=0 AND (C)=1 if drive is not ready.
CHKRDY  JMP  [CHKVEC]
*
* Quick drive ready check.
* Entry: (X) = FCB address (3,X contains drive number).
* Exit:  (B) = Error condition, (Z)=0 AND (c)=1 if drive not ready.
CHKQIK  JMP  [QUIVEC]
*
* Init (cold start).
* Entry: no parameters.
* Exit: no change.
DINIT   CLRA
DINIT1  STA  DRVNUM  Init each valid drive in turn.
        LDX  #DRVNUM-3
        BSR  DRVSEL
        BCS  DINIT2
        JSR  [INIVEC]
DINIT2  LDA  DRVNUM
        INCA
        CMPA  #4
        BNE  DINIT1
        RTS
*
* Warm start.
* Entry: no parameters.
* Exit: no change.
DWARM    JMP  [WARVEC]
*
* Seek track.
* Entry: (A) = Track number.
*        (B) = Sector number.
* Exit:  (B) = Error condition, (Z)=1 if no error.
SEEKTS  JMP  [SEEVEC]
*
*
*****************************************************
* ROMdisk drivers                                   *
* ---------------                                   *
* Drivers to support a ROMdisk in the external RAM  *
* of the SYS09. The ROMdisk base address is $10000   *
*****************************************************
* Dummy return for ROM disk (write protected!)
*
* MAP RAM DISK INTO MEMORY SPACE
*
MAPIN   TFR   CC,A     ; Save state of interrupt masks
        STA   CCSAVE
        ORCC  #FFLAG+IFLAG ; Mask interrupts while IO mapped out
        LDU   #DTYPTAB  ; Point to Drive Type table
        LDB   DRVNUM   ; Get working drive number
        LDB   B,U
        LDU   #DOFFTAB
        LDA   TRACK
        ADDA  B,U      ; Add Base offset into RAM
        ANDA  #$F0     ; Mask MSN
        STA   ,-S      ; Save A on stack
* 
        LDA   SECTOR
        SUBA  #1       ; Sectors 1 to 14 => 0 to 13
        EORA  #$0F     ; Complement LSNybble
        ANDA  #$0F
*
        ADDA  ,S+       ; Add sector to LSN of Track and pop
        STA   DATREG+MAPPAG
*
        LDA   TRACK   ; LSN of Track indexes into 4K page
        ANDA  #$0F
        ADDA  #MAPPAG*16
        CLRB
        TFR   D,U
        RTS
*
* MAP RAM DISK OUT OF MEMORY
*
MAPOUT  LDA   #MAPPAG  ; Point to the Flex page
        EORA  #$0F     ; Complement LSNybble
        STA   DATREG+MAPPAG ; map in Flex page
        LDA   CCSAVE   ; restore interrupt masks
        TFR   A,CC
        RTS
*
* Seek track and sector
* A holds track number (0-32)
* B holds sector number (1-14)
*
ESEEK   STA   TRACK
        STB   SECTOR
        ANDCC #$FE   ; CLEAR CARRY
        ORCC  #$04   ; SET Z
        RTS
*
* MARK DISK READ ONLY
*
EDUMMY  LDB  #$40
        TSTB
        ORCC  #$01
        RTS
*
EREAD   PSHS X,Y,U push sequentialy to preserve order on stack
        LBSR ESEEK
        LBSR MAPIN build external ram address
*
        LDY #BUFFER
        CLRB
ERLOOP1 LDA 0,U+ move 256 bytes to buffer from external RAM
        STA 0,Y+
        DECB
        BNE ERLOOP1
*
        LBSR MAPOUT
*
        LDY #BUFFER
        CLRB
ERLOOP2 LDA 0,Y+ move 256 bytes from buffer to Flex RAM
        STA 0,X+
        DECB
        BNE ERLOOP2
*
        CLRB
        PULS X,Y,U,PC  restore all registers
*
* check for marker bytes $AA55 in first bytes of first track/sector
*
*ECHECK  CLRA 
*        LDB  #1
*        LDX  #BUFFER
*        BSR  EREAD
*        LDD  BUFFER
*        CMPD  #$AA55
*        BNE  EERR
*        LBRA  DDUMMY
*EERR    LDB  #$80 not ready bit set
*        TSTB
*        ORCC  #$01
*        RTS
ECHECK CLRB
       RTS
*
* Write Sector
*
EWRITE  PSHS X,Y,U
        LBSR ESEEK
        LDU  #DTYPTAB  ; Point to Drive Type table
        LDB  DRVNUM    ; Get working drive number
        LDB  B,U       ; Fetch Drive type
        CMPB #DTYPRAM  ; Is it a RAM Disk ?
        BEQ  EWOK      ; Yep, can write to it
        CMPB #DTYPROM  ; Allow writes to ROM Disk too
        BEQ  EWOK
        LBRA EDUMMY    ; Nope report read only 
*
EWOK    LDY #BUFFER
        CLRB
EWLOOP1 LDA 0,X+ move 256 bytes to buffer from Flex RAM
        STA 0,Y+
        DECB
        BNE EWLOOP1
*
        LBSR MAPIN
*
        LDY #BUFFER
        CLRB
EWLOOP2 LDA 0,Y+ move 256 bytes from buffer to external RAM
        STA 0,U+
        DECB
        BNE EWLOOP2
*
        LBSR MAPOUT
*
        CLRB
        PULS X,Y,U,PC
*
*
*****************************************************
* FlexNet drivers                                   *
* ---------------                                   *
* Drivers to support a remote connection via the    *
* serial port using the FlexNet protocol as defined *
* in FLEXNet_421B                                   *
*****************************************************
*
*
* read sector from remote drive
*
NREAD   PSHS    B
        PSHS    A
        CLR     CHKSUM          clear checksum
        CLR     CHKSUM+1
*       
        LDA     #'s             Send read sector command
        JSR     SCHAR
        BCC     NRD_DNR         if timeout, then flag drive not ready
*
        LDA     DRVNUM           send drive
        JSR     SCHAR
        BCC     NRD_DNR           
*
        PULS    A               send track
        JSR     SCHAR
        BCC     NRD_DNR          
*
        PULS    A               send sector
        JSR     SCHAR
        BCC     NRD_DNR          
*
* transfer 256 bytes
        CLRB                    
NREAD1  JSR     RCHAR           read byte
        BCC     NRD_DNR         if timeout, then flag drive not ready
        STA     0,X+
        ADDA    CHKSUM+1        update checksum
        STA     CHKSUM+1
        BCC     NREAD2         
        INC     CHKSUM
NREAD2  DECB         
        BNE     NREAD1          
*
* compare checksums
        JSR     RCHAR           get checksum msb
        BCC     NRD_DNR
        PSHS    A
        JSR     RCHAR           get checksum lsb
        BCC     NRD_DNR
        TFR     A,B            
        PULS    A               
        CMPD    CHKSUM          compare checksums
        BNE     NRD_ERR         if checksum error, then flag crc read error
*
        LDA     #ACK            no checksum error, send ACK char
        JSR     SCHAR
        BCC     NRD_DNR 
        CLRB                    all OK, flag no error
        BRA     NRD_END
*
NRD_DNR LDB     #16             flag drive not ready
        BRA     NRD_END
*
NRD_ERR LDA     #NAK            send NAK
        JSR     SCHAR
        BCC     NRD_DNR  
        LDB     #09             flag crc read error
*
NRD_END STB     CHKSUM          used by VERIFY
        TSTB                    
        RTS
*
*
* write sector to remote drive
*
NWRITE  PSHS B
        PSHS A
        CLR     CHKSUM          clear checksum
        CLR     CHKSUM+1
*       
        LDA     #'r             Send write sector command
        JSR     SCHAR
        BCC     NRD_DNR         if timeout, then flag drive not ready
*
        LDA     DRVNUM           send drive
        JSR     SCHAR
        BCC     NRD_DNR           
*
        PULS    A               send track
        JSR     SCHAR
        BCC     NRD_DNR          
*
        PULS    A               send sector
        JSR     SCHAR
        BCC     NRD_DNR          
*
* transfer 256 bytes
        CLRB                    
NWRITE1 LDA     0,X+
        JSR     SCHAR           write byte
        BCC     NRD_DNR         if timeout, then flag drive not ready
        ADDA    CHKSUM+1        update checksum
        STA     CHKSUM+1
        BCC     NWRITE2         
        INC     CHKSUM
NWRITE2 DECB         
        BNE     NWRITE1          
*
* compare checksums
        LDA     CHKSUM
        JSR     SCHAR           send checksum msb
        BCC     NRD_DNR
        LDA     CHKSUM+1
        JSR     SCHAR           send checksum lsb
        BCC     NRD_DNR
*
        JSR     RCHAR           get checksum response
        BCC     NRD_DNR        
        CMPA    #ACK
        BNE     NWR_ERR         if checksum error, then flag write error    
*
        CLRB                    all OK, flag no error
        BRA     NWR_END
*
NWR_ERR LDB     #10             flag write error
*
NWR_END STB     CHKSUM          used by VERIFY
        TSTB                    
        RTS
*
*
*   verify last sector written to remote drive
*
NVERIFY LDB     CHKSUM         test last checksum
        TSTB
        RTS
*
*
*   quck check and check drive ready
*
NCHECK  LDA     #'Q             quick check command
        JSR     SCHAR
        BCC     NCK_ERR         if timeout, then flag drive not ready

        JSR     RCHAR           get response from host
        BCC     NCK_ERR
        CMPA    #ACK
        BNE     NCK_ERR         if NAK, then flag drive not ready

        CLRB                    all OK, flag drive ready
        BRA     NCK_END
*
NCK_ERR LDB     #16             report drive not ready
        ORCC    #$01            check needs carry set as well
*
NCK_END TSTB
        RTS
*
*
* recieve char from remote drive.
* timeout if no response for approx 1s.
* Entry: no parameters
* Exit:  (A) = recieved char, (C)=1 if valid char, (C)=0 if timeout.
*
RCHAR   PSHS    X,Y
*
        LDX     #1000         1000x inner loop
RCHAR1  LDY     #DELCON       delay constant for inner loop (approx 1ms).
RCHAR2  LDA     ACIAC1        test for recieved char
        ASRA
        BCS     RCHAR3        get character
        LEAY    -1,Y          else, continue to count delay
        BNE     RCHAR2
        LEAX    -1,X
        BNE     RCHAR1
        PULS    X,Y,PC        return with error if timed out
*
RCHAR3  LDA     ACIAD1        return data (carry bit still set)
        PULS    X,Y,PC
*
*
* transmit char to remote drive.
* timeout if no response for approx 1s. (allows for use of hardware flow control)
* Entry: (A) = char to transmit
* Exit:  (A) = recieved char, (C)=1 if valid char, (C)=0 if timeout.
*
SCHAR   PSHS    X,Y
        PSHS    A
*
        LDX     #1000         1000x inner loop
SCHAR1  LDY     #DELCON       delay constant for inner loop (approx 1ms).
SCHAR2  LDA     ACIAC1        test for space in transmit FIFO
        ASRA
        ASRA
        BCS     SCHAR3        send character
        LEAY    -1,Y          else, continue to count delay
        BNE     SCHAR2
        LEAX    -1,X
        BNE     SCHAR1
        PULS    A
        PULS    X,Y,PC        return with error if timed out
*
SCHAR3  PULS    A
        STA     ACIAD1        send data (carry bit still set)
        PULS    X,Y,PC
*
** 'UF' Format RAMdisc to FLEX standard.
*
DISFOS  FCB $0A,$0D 
        FCC 'Formating RAMdisk... '
        FCB 4
MESS6   FCB $0A,$0D,4
        FCC 'Ramdisk not allocated! '
        FCB 4
*
UFSUB   LDX #DISFOS
        JSR PDATA1
        LDX #DTYPTAB            search for allocated ramdisk
        CLRB
FMT9    LDA B,X
        CMPA #DTYPRAM           driver type 1 is ramdisk
        BEQ FFOUND
        INCB
        CMPB #4         end of table? then not allocated.
        BNE FMT9
        LDX #MESS6
        JSR PDATA1
        RTS
*
FFOUND  STB DRVNUM
        LDX #DRVNUM-3
        JSR DRVSEL
*
* set up free chain
*
        LDX #BUFFER clear out buffer
        CLRA
        CLRB
DFL1    STA 0,X+
        DECB
        BNE DFL1
*
        CLR TRACK
        LDA #1
        STA SECTOR
DFL2    LDX #BUFFER
        LDA TRACK
        STA 0,X
        LDA SECTOR
        INCA
        CMPA #RMAXSEC+1 last sector on track?
        BNE DFL3
        INC 0,X
        LDA #1
DFL3    STA 1,X
        LDA TRACK
        LDB SECTOR
        JSR WRITSC
        INC SECTOR
        LDA SECTOR
        CMPA #RMAXSEC+1
        BNE DFL2
        LDA #1
        STA  SECTOR
        INC TRACK
        LDA TRACK
        CMPA #RMAXTRK
        BNE DFL2
* break free chain at last track/sector
        LDX  #BUFFER
        LDA  #RMAXTRK-1
        LDB  #RMAXSEC
        JSR  READSC
        LDX  #BUFFER
        CLR  0,X
        CLR  1,X
        LDA  #RMAXTRK-1
        LDB  #RMAXSEC
        JSR  WRITSC 
* set up sector structure, SIR, directory etc
        LDX  #BUFFER
        CLRA
        LDB  #RMAXSEC
        JSR  READSC
        LDX  #BUFFER
        CLR  0,X break end of directory chain
        CLR  1,X
        CLRA
        LDB  #RMAXSEC
        JSR  WRITSC
*
        LDX  #BUFFER
        CLRA
        LDB  #3 set up SIR
        JSR  READSC
        LDX  #BUFFER
        CLR  0,X break forward link
        CLR  1,X
        LDD  #$5241 set volume name (RAMDISK )
        STD  16,X
        LDD  #$4D44
        STD  18,X
        LDD  #$4953
        STD  20,X
        LDD  #$4B20
        STD  22,X
        LDD  #1 volume number
        STD  27,X
        LDD  #$0101 first trk/sec  01-01
        STD  29,X
        LDA  #RMAXTRK-1
        LDB  #RMAXSEC
        STD  31,X
        STD  38,X
        LDD  #RTOTSEC total DATA sectors (2912-14)
        STD  33,X
*
        LDA #01 month   set default creation date (SYS09's birthday!)
        STA 35,X
        LDA #07 day
        STA 36,X
        LDA #07 year
        STA 37,X
*
RF3     CLRA
        LDB  #3
        JSR  WRITSC
*
        LDX #BUFFER
        CLRA
        LDB #1
        JSR READSC
        LDX #BUFFER
        LDA #$AA set the init flag
        STA 0,X
        LDA  #$55
        STA 1,X
        CLRA
        LDB #1
        JMP WRITSC
*
********************************
*    System specific Boot      *
*    command goes here.        *
********************************
*
* Boot FLEX from the FPGA's internal pre-loaded scratch RAM
*
UBMESS  FCB $08, $08
        FCC 'Booting internal FLEX....'
        FCB $0D,$0A,$04
*
UBSUB   LDX #UBMESS
        JSR PDATA1
*
        LDX #$D3E5
        LDY #CONTAB Overlay console driver table
UB1     LDD 0,Y++
        STD 0,X++
        CMPX #$D3FD
        BNE UB1
*
        LDX #$DE00 Overlay disk driver table
        LDY #DISTAB
UB2     LDD 0,Y++
        STD 0,X++
        CMPX #$DE1E
        BNE UB2
*
UBEND   JMP $CD00
*
* FLEX console jump table.
CONTAB  FDB INPNE       INPUT NO ECHO
        FDB DUMMY       INTERRUPT HANDLER
        FDB MONRAM+$02 SWI VECTOR
        FDB MONRAM+$08 IRQ VECTOR
        FDB DUMMY       TIMER OFF
        FDB DUMMY       TIMER ON
        FDB DUMMY       TIMER INITIALIZATION
        FDB CONTRL      MONITOR
        FDB DUMMY       TERMINAL INITIALIZATION
        FDB STATUS      INPUT CHECK
        FDB OUTP        TERMINAL OUTPUT
        FDB INPE        TERMINAL INPUT WITH ECHO
*
* FLEX disk jump table.
DISTAB  JMP READSC
        JMP WRITSC
        JMP BUSY
        JMP RESTR1
        JMP DRVSEL
        JMP CHKRDY
        JMP CHKQIK
        JMP DINIT
        JMP DWARM
        JMP SEEKTS
*
* Monitor jumps
*
PDATA1  JMP [PDATAV]
OUTP    JMP [OUTCHV]
INPE    JMP [INCHEV]
INPNE   JMP [INCHV]
STATUS  JMP [INCHKV]
CONTRL  JMP [MONITV]
DUMMY   RTS
*
** 'UL' LOAD ROM DISK VIA SERIAL PORT
*
ULMES   FCC  'Serial ROM Disk upload ...'
        FCB  $0D,$0A,$04
ULMES1  FCC  'ROM Disk Loaded'
        FCB  $0D,$0A,$04
*
ULSUB   LDX  #ULMES
        JSR  PDATA1
*
        LDA  #$00
        STA  DRVNUM
        CLRA         TRACK 0
        LDB  #$01    SECTOR 1
ULLOOP0 STA  TRACK
        STB  SECTOR`
        LBSR MAPIN
*
        CLRB  xfer 256 bytes at a time.
ULLOOP1 JSR  LRBYTE transfer should be hex bytes
        STA  ,U+
        DECB
        BNE  ULLOOP1
*
        LBSR MAPOUT
*
        LDA  TRACK
        LDB  SECTOR
        INCB
        CMPB #EMAXSEC+1
        BNE  ULLOOP0
        LDB  #1
        INCA
        CMPA #EMAXTRK
        BNE  ULLOOP0
*
ULEXIT  LDX  #ULMES1
        JMP  PDATA1
*
* Read a byte from the serial port
*
LRBYTE  PSHS B
        BSR  LRHEX                  Get hex digit.
        ASLA
        ASLA                           Shift to msb.
        ASLA
        ASLA
        TFR  A,B                    Save in B.
        BSR  LRHEX                  Get next digit.
        PSHS B
        ADDA 0,S+                    Add together bytes.
        PULS B,PC
*
LRHEX   JSR  INTER
        BVS  LRHEX
        SUBA #$30                   Remove ascii bias.
        BMI  LRHEX
        CMPA #$09                   Number?
        BLE  LRHEX1                 Yes.
        CMPA #$11                   Keep testing.
        BMI  LRHEX
        CMPA #$16
        BGT  LRHEX
        SUBA #$07
LRHEX1  RTS
*
* ACIA INPUT TEST
*
INTEST  LDA ACIAC1
        BITA #$01
        RTS
*
* RESET ACIA
*
ACIRST  LDA #$03 master reset
        STA  ACIAC1
        LDA #$11
        STA ACIAC1
        RTS
*
* ACIA INPUT
*
INTER   LDA  #16
        STA  DELCNT+0
        CLR  DELCNT+1
        CLR  DELCNT+2
INTER0  LDA  ACIAC1
        BITA #$01
        BNE  INTER1
        BITA #$78
        BEQ  INTER2
        BSR  ACIRST
        BRA  INTER
*
INTER1  LDA  ACIAD1
        ANDCC #VFLAG
        RTS
*
INTER2  DEC  DELCNT+2
        BNE  INTER0
        DEC  DELCNT+1
        BNE  INTER0
        DEC  DELCNT+0
        BNE  INTER0
        CLRA
        ORCC #VFLAG
        RTS
*
* ACIA OUTPUT
*
OUTTER  PSHS A
*
OUTTE1  LDA ACIAC1
        BITA #$02
        BNE  OUTTE2
        BITA #$78
        BEQ  OUTTE1
        BSR  ACIRST
        BRA  OUTTE1
*
OUTTE2  PULS A
        STA ACIAD1
        RTS
*
** 'UX' Xmodem ROM Disk upload
*
UXMES   FCB $0D,$0A
        FCC 'Xmodem ROM Disk Upload'
        FCB 4
UXMES1  FCB $0D,$0A
        FCC 'Upload Complete'
        FCB 4
UXMES2  FCB $0D,$0A
        FCC 'Upload Error'
        FCB 4
*
UXSUB   LDX #UXMES
        LBSR PDATA1
*
        LDA  #1
        STA BLKNUM
        LDX  #XSTSTR
        STX  XSTATE
*
        LDA  #$00
        STA  DRVNUM
        CLRA         TRACK 0
        LDB  #$01    SECTOR 1
UXLOOP0 STA  TRACK
        STB  SECTOR
        LBSR MAPIN
*
        CLRB       xfer 256 bytes at a time.
UXLOOP1 LBSR XBYTE transfer should be hex bytes
        BCS  UXERR
        STA  ,U+
        DECB
        BNE  UXLOOP1
*
        LBSR MAPOUT
*
        LDA  TRACK
        LDB  SECTOR
        INCB
        CMPB #EMAXSEC+1
        BNE  UXLOOP0
        LDB  #1
        INCA
        CMPA #EMAXTRK
        BNE  UXLOOP0
*
UXEXIT  LDX  #UXMES1
        JMP  PDATA1
*
UXERR   LBSR MAPOUT
        LDX  #UXMES2
        LBRA PDATA1
*
* Get a Byte using XModem protocol
* Carry clear => no errors
* Carry set   => errors
*
XBYTE   PSHS X
        LDX  XSTATE
*
XBYTE0  LBSR INTER
        BVC  XBYTE1
        LDA  #NAK
        LBSR OUTTER
        LDX  #XSTSTR
        BRA  XBYTE0
*
XBYTE1  JSR  ,X
        BNE  XBYTE0
        STX  XSTATE
        PULS X,PC
*
* START - LOOK FOR SOH (START OF HEADER) = $01
*
XSTSTR  CMPA #SOH
        BNE  XSTSTR1
        LDX  #XSTBLK
        ANDCC #$FF-CFLAG-ZFLAG No abort, no valid data (no exit)
        RTS
*
XSTSTR1 CMPA #EOT
        BNE  XSTSTR2
        LDA  #ACK
        LBSR OUTTER
        ORCC  #CFLAG+ZFLAG  Set (c)=1 abort & exit
        RTS
*
XSTSTR2 CMPA #CAN
        BNE  XSTSTR3 
        ORCC  #CFLAG+ZFLAG  Set (c)=1 abort & exit
        RTS
*
XSTSTR3 ANDCC #$FF-CFLAG-ZFLAG
        RTS
*
* Got SOH
* Now get block number
*
XSTBLK  CMPA BLKNUM
        BNE  XSTBLKE
        LDX  #XSTCOM
        ANDCC #$FF-CFLAG-ZFLAG No abort, No valid data (no exit)
        RTS
*
* Error in block number
*
XSTBLKE LDA  #NAK
        LBSR OUTTER
        LDX  #XSTSTR
        ANDCC #$FF-CFLAG-ZFLAG No abort, No valid data (no exit)
        RTS
*
* Get complement of block number
*
XSTCOM  COMA
        CMPA BLKNUM
        BNE  XSTBLKE
        CLR  CHKSUM
        LDA  #128
        STA  BYTCNT
        LDX  #XSTDAT
        ANDCC #$FF-CFLAG-ZFLAG No abort, No valid data (no exit)
        RTS
*
* Get data bytes
*
XSTDAT  PSHS A
        ADDA CHKSUM
        STA  CHKSUM
        PULS A
        DEC  BYTCNT
        BNE  XSTDAT1
        LDX  #XSTCHK
XSTDAT1 ANDCC #$FF-CFLAG No abort
        ORCC #ZFLAG      Valid data (exit)
        RTS
*
* Byte count reached zero
* Check checksum byte
*
XSTCHK  CMPA CHKSUM
        BNE  XSTCHK1 retry if wrong checksum
*
* Checksum OK ... 
* increment block number
* and send ACK
*
        INC  BLKNUM
        LDA  #ACK
        BRA  XSTCHK2
*
* Checksum Error detected ...
* Reset Sector counter in ACCB to last 128 byte boundary
* and send NAK
*
XSTCHK1 PSHS B
        TFR  U,D
        DECB
        ANDB #128 
        TFR  D,U
        PULS B
        LDA  #NAK
XSTCHK2 LBSR OUTTER
        LDX  #XSTSTR
        ANDCC #$FF-CFLAG-ZFLAG No abort, no valid data (no exit)
        RTS
*
** 'UP' Load ROMdisk via config PROM.
*
UPMES   FCB  $08,$08
        FCC  'Load ROM disk from config PROM.'
        FCB  4
UPMES1  FCC  'Found SYNC, loading data...'
        FCB  $0A,$0D,4
UPMES2  FCC  'ROM Disk Loaded.'
        FCB  $0A,$0D,4
UPMES3  FCC  'ROM Disk Not Found.'
        FCB  $0A,$0D,4
*
UPSUB   LDX  #UPMES
        JSR  PDATA1
*
        BSR  UPRESET
        LDY  #$0020  Set up count for 2 MBit
        LDX  #$0000
UPSUB1  BSR  UPBIT   Shift in bit
        BSR  UPSYNC  Test for Sync pattern`
        BEQ  UPSUB4  Skip if found
        LEAX -1,X    Count Down inner loop
        CMPX #$0000
        BNE  UPSUB1   Branch if inner loop not complete
        LEAY -1,X    Count down outer loop
        CMPY #$0000
        BNE  UPSUB1   Branch if outer loop not complete
*
        LDX  #UPMES3 2MBits scanned, no synch, report error
        JMP  PDATA1
*
UPSUB4  LDX  #UPMES1 Sync found, now load disk
        JSR  PDATA1
*
        CLRA
        STA  DRVNUM   select Drive 0
        LDB  #$01
UPSUB2  STA  TRACK   track 0
        STB  SECTOR  sector 1
*
        LBSR MAPIN   map in buffer
        CLRB         256 byte sector
UPSUB3  BSR  UPBYTE  read byte from prom
        STA  ,U+     Store in buffer
        DECB
        BNE  UPSUB3  Loop until sector read`
        LBSR MAPOUT  map out buffer
* 
        LDA  TRACK   Advance sector
        LDB  SECTOR
        INCB
        CMPB #EMAXSEC+1 Wrap on max sector count
        BNE  UPSUB2
        LDB  #1
        INCA          Advance track
        CMPA #EMAXTRK
        BNE  UPSUB2
*
UPEXIT  LDX  #UPMES2  Load complete, report message 
        JMP  PDATA1
*
* Reset Serial PROM
*
UPRESET LDA  #PRSTHI    Strobe the reset line
        STA  PROMREG
        LDA  #PRSTLO
        STA  PROMREG
        LDX  #$0000     Delay a while`
UPRST1  LEAX -1,X
        CMPX #$0000
        BNE  UPRST1
        STX  SYNCREG+0  Clear Sync Shift Register
        STX  SYNCREG+2
        RTS
*
* Input 1 Bit From PROM
*
UPBIT   LDA  #PCLKHI
        STA  PROMREG
        LDA  #PCLKLO
        STA  PROMREG
        LDA  PROMREG
        LSRA
        ASL  SYNCREG+3
        RTS
*
* Test for 32 bit Sync Word
*
UPSYNC  ROL  SYNCREG+2
        ROL  SYNCREG+1
        ROL  SYNCREG+0
        LDD  #SYNCLO
        CMPD SYNCREG+2
        BNE  UPSYNCX
        LDD  #SYNCHI
        CMPD SYNCREG+0
UPSYNCX RTS
*
* Input 1 Byte From PROM
*
UPBYTE  PSHS B
        LDB  #8
UPBYTE1 BSR  UPBIT
        DECB
        BNE  UPBYTE1
        LDA  SYNCREG+3
        PULS B,PC 
* 
***** NEXTCMD ***** 
* 
NEXTEXT LBSR INPE  GET ONE CHAR. FROM TERMINAL 
        ANDA #$7F STRIP PARITY FROM CHAR. 
        TFR  A,B
        LDA  #$20 
        LBSR OUTP PRNT SPACE 
        CMPB #$60 
        BLE NXTEX0 
        SUBB #$20 
* 
***** DO TABLE LOOKUP ***** 
*   FOR COMMAND FUNCTIONS 
* 
NXTEX0  LDX #EXTTAB    POINT TO JUMP TABLE 
NXTEX1  CMPB ,X+       DOES COMMAND MATCH TABLE ENTRY ? 
        BEQ  JMPEXT    BRANCH IF MATCH FOUND 
        LEAX 2,X       POINT TO NEXT ENTRY IN TABLE 
        CMPX #EXTEND   REACHED END OF TABLE YET ? 
        BNE  NXTEX1    IF NOT END, CHECK NEXT ENTRY 
        LDX  #MSGWHAT  POINT TO MSG "WHAT?" 
        LBRA PDATA1    PRINT MSG AND RETURN
JMPEXT  JMP  [,X]      JUMP TO COMMAND ROUTINE 
*
* EXTENDED COMMAND JUMP TABLE 
* 
EXTTAB EQU * 
       FCC 'B'   BOOT FLEX
       FDB UBSUB
       FCC 'L'   LOAD ROM DISK OVER SERIAL PORT
       FDB ULSUB 
       FCC 'F'   FORMAT RAM DISK
       FDB UFSUB 
       FCC 'P'   LOAD ROM DISK FROM PROM
       FDB UPSUB 
       FCC 'X'   XMODEM ROM DISK UPLOAD
       FDB UXSUB
* 
EXTEND EQU * 
*
MSGWHAT FCC "WHAT ?"
        FCB $0A,$0D,$04
       END