opt    h-f+
    org    $d800
;
PBI_Entry:
PBI_rev:    .byte    '1.0';
PBI_DEVID1:    .byte    0x80,0x00
PBI_PDIOR:    jmp    Karin_IO    ;D90B
PBI_PDINT:    jmp    Karin_IRQ    ;D898
PBI_DEVID2:    .byte    0x91
PBI_PDSPC:    .byte    0x00
PBI_PDVOPV:    .word    Karin_CIO_Open-1    ;D900
PBI_PDVCLV:    .word    Karin_CIO_Close-1    ;D900
PBI_PDVGBV:    .word    Karin_CIO_GetByte-1    ;D8F6
PBI_PDVPBV:    .word    Karin_CIO_PutByte-1    ;D900
PBI_PDVSTV:    .word    Karin_CIO_Status-1    ;D900
PBI_PDVSPV:    .word    Karin_CIO_Special-1    ;D900
PBI_PDINIT:    
;-----------------------------------------------------------------------------------------
Karin_Init:
        ldx    #$4E            ; N: device
        ldy    #$8F
        lda    #$E4            ; Point to Generic Parallel Device Table (GPDVV, 0xE48F)
        jsr    PENTV            ; install new device
        lda    #$80            ; Karin-Maxi fixed PBI device number
        sta    PDVMSK            ; report that back to the system
        lda    #$D0
        sta    WD177x_Command        ; read track command
        ldx    #$1E
Karin_Init_wait1:
        dex
        bne    Karin_Init_wait1
        stx    Karin_EnableIP        ; enable Index Pulse singal comming from the drive
        stx    Karin_DslctDS0
        stx    Karin_DslctDS1        ; deselect both drives
Karin_Init_l1:    stx    Karin_AssertIP        ; emulate Index Pulse
        php                ;
        plp                ; wait...
        php                ;
        plp                ;
        stx    Karin_DessertIP        ; Index Pulse end
        lda    WD177x_Status
        bmi    Karin_Init_l1        ; repeat, if Motor On
        lda    WARMST
        bne    Karin_Init_End        ; end here if this is warm start
        stx    Karin_EnableDD
        inx                ; set drive numer to #1
        lda    Karin_Config
        and    #$10            ; auto config?
        bne    Karin_AutoConfigure    ; yes, so sense drives
Karin_Init_Config_l1:
        sta    Karin_DslctDS0
        sta    Karin_DslctDS1        ; deselect both drives
        sta    Karin_SlctDS0,X        ; select desired drive
        lda    Karin_Config        ; load configuration register
        and    Config_Table,X        ; manual configured for 6ms?
        beq    Karin_Init_skip1    ; yes, so skip setting it to 3ms
        lda    #$03
        sta    ACMVAR+4,X
Karin_Init_skip1:
        lda    #$08
        ora    ACMVAR+4,X
        sta    WD177x_Command        ; restore command (seek to track #0)
Karin_Init_wait2:
        bit    Karin_Status
        bmi    Karin_Init_wait2    ; wait until seek is complete
        lda    WD177x_Status
        and    #$04
        sta    ACMVAR,X        ; bit 2 ov ACMVAR is now drive-present flag
        beq    Karin_Init_Next        ; no drive here, check next drive
        lda    Karin_Config
        and    Config_Table+2,X    ; check if configured for 80 tracks
        beq    Karin_Init_Next        ; no, then configuration for that drive is done
        lda    ACMVAR,X
        ora    #$10
        sta    ACMVAR,X
Karin_Init_Next:
        dex
        bpl    Karin_Init_Config_l1
Karin_Init_End:
Karin_IRQ:      rts
;-----------------------------------------------------------------------------------------
Karin_AutoConfigure:
        sta    Karin_DslctDS0
        sta    Karin_DslctDS1        ; deselect both drives
        sta    Karin_SlctDS0,X        ; select only actual one
        lda    #$08
        sta    WD177x_Command        ; restore (seek to track 0) with spin-up sequence
Karin_AutoC_wait1:
        bit    Karin_Status
        bmi    Karin_AutoC_wait1    ; wait for INTRQ from WD177x
        lda    WD177x_Status
        and    #$04            ; bit 2 in ACMVAR,x is now drive-found flag
        sta    ACMVAR,X
        beq    Karin_AutoC_Next    ; track 0 not found, check next drive
        lda    #$03            ; set stepping for 3ms
Karin_AutoC_ChangeStepping:
        sta    ACMVAR+4,X        ; now ACMVAR+4,x contains stepping information 0x03 = 3ms, 0x00 = 6ms
        ldy    #45
        sty    WD177x_Data        ; try to go to track 45
        lda    #$10
        ora    ACMVAR+4,X        ; build command value with apriopriate flags
        sta    WD177x_Command        ; seek command
Karin_AutoC_wait2:
        bit    Karin_Status
        bmi    Karin_AutoC_wait2    ; wait for INTRQ
Karin_AutoC_Step_l1:
        lda    #$60
        sta    WD177x_Command        ; step-out
Karin_AutoC_wait3:
        bit    Karin_Status
        bmi    Karin_AutoC_wait3    ; wait for INTRQ
        dey
        lda    WD177x_Status
        and    #$04            ; are we on track 0?
        beq    Karin_AutoC_Step_l1    ; no, so step out again
        lda    #$00            ; set stepping to 6ms (in case of retry) and reset 80 track drive marker
        cpy    #$00            ; track number is 0?
        beq    Karin_AutoC_80Tracks    ; yes, 80 track drive found
        cpy    #$09            ; less than 9 tracks remaining?
        bcc    Karin_AutoC_40Tracks    ; yes - so 40 track drive found, and stepping is 3ms
                        ; no - set stepping to 6ms and try again
        bcs    Karin_AutoC_ChangeStepping
Karin_AutoC_80Tracks:
        lda    #$10            ; set 80 track drive marker
Karin_AutoC_40Tracks:
        ora    ACMVAR,X
        sta    ACMVAR,X        ; save status of that drive
Karin_AutoC_Next:
        dex
        bpl    Karin_AutoConfigure
        rts        
;-----------------------------------------------------------------------------------------
; Karin CIO routines - just for fun
;-----------------------------------------------------------------------------------------
Karin_CIO_GetByte:
        lda    RANDOM            ;get random byte
        ldy    RANDOM
        cpy    #$88            ; is it EOF?
        beq    Karin_CIO_GetByte_EOF    ; if so, return EOF
Karin_CIO_Open:
Karin_CIO_Close:
Karin_CIO_PutByte:
Karin_CIO_Status:
Karin_CIO_Special:
        ldy    #$01            ; set status to OK
Karin_CIO_GetByte_EOF:
        sec
        rts
;-----------------------------------------------------------------------------------------
Config_Table:
    .byte $04,$08,$01,$02

  D0 - DS0 number of tracks, 0 - 80 tracks drive, 1 - 40 tracks drive
  D1 - DS1 number of tracks, 0 - 80 tracks drive, 1 - 40 tracks drive
  D2 - stepping for DS0 - 0 - 3ms, 1 - 6ms
  D3 - stepping for DS1 - 0 - 3ms, 1 - 6ms
  D4 - 0 - Auto configure, 1 - manual config (depends on D2-D5)
  D5 - boot order - 0 - SIO, 1 - KARIN MAXI first