TPUG - Toronto PET Users Group/TPUG Users Group CD/TPUG Users Group CD.iso/CRS/crs53.d81/28may87s.pma/FAST8502.ASM

Assembly Source File | 1979-12-31 | 18KB | 922 lines

    title    '8502 drivers        4 Mar 86'

    maclib    x6502

    maclib    z80

    maclib    cxequ

$-MACRO
;
;      COMMON EQUATES
;
; page 0 variables, from 0a to 8f are usable
;
prtno        equ    0000Ah        ; 0Ah
second$adr    equ    prtno+1        ; 0Bh
DATCHN        equ    second$adr+1    ; 0Ch
CMDCHN        equ    datchn+1    ; 0Dh
DEVNO        equ    cmdchn+1    ; 0Eh
adr$1        equ    devno+1        ; 0Fh
temp$byte    equ    adr$1+2        ; 11h
;        equ    temp$byte+1    ; 12h

pal$nts        equ    00a03h        ; FF=PAL=50Hz 0=NTSC=60Hz
serial        equ    00a1ch
d2pra        equ    0dd00h        ; serial control port (clk and data)
d1sdr        equ    0dc0ch        ; Fast serial data reg.
d1icr        equ    0dc0dh        ; serial channel interrupt control reg

clkbit        equ    10h        ; d2pra clock bit mask
;
;    KERNAL EQUATES
;
K$spin$spout    equ    0FF64h        ; C=0 spin  C=1 spout

K$setbnk    equ    0FF68h        ; set the logical bank # for open
                    ;  disk commands
                    ;I A=load and store bank # (C128 type bank)
                    ;  X=file name bank #

K$readst    equ    0FFB7h        ; read status byte
                    ;O A = status

K$setlfs    equ    0FFBAh        ; setup a logical file
                    ;I A=logical file #
                    ;  X=device # (0-31)
                    ;  Y=seconday command (FF if nane)

K$setnam    equ    0FFBDh        ; set up file name for OPEN
                    ;I A=name length
                    ;  X=low byte pointer to name
                    ;  Y=high byte pointer to name

K$open        equ    0FFC0h        ; open a logical file (after setlfs
                    ; and setnam)
                    ;O A = error # (1,2,4,5,6,240)

K$chkin        equ    0FFC6h        ; open a channel for input
                    ;I X = logical file #
                    ;O A = errors #(0,3,5,6)

K$chkout    equ    0FFC9h        ; open a channel for output
                    ;I X = logical file #
                    ;O A = error #(0,3,5,7)

K$clrchn    equ    0FFCCh        ; clears ALL I/O channel

K$chrin        equ    0FFCFh        ; get a character from input channel
                    ;O A=input character

K$chrout    equ    0FFD2h        ; output a character to output channel
                    ;I A =output char

;GETIN        equ    0FFE4h

K$clall        equ    0FFE7h        ; close ALL open logical files

K$close        equ    0FFC3h        ; close a logical file
                    ;I A = logical channel # to be closed
                    ;O A = error #(0,240)

RESET        equ    0FFFCh

    PAGE
;
    org    bios8502
;
; **** THIS IS THE COMMAND LOOP ****
;
start:
  if    use$fast
    @ldx    sys$speed    ;-K  get desired system speed
    @stx    vic$speed    ;-K  set system speed
  endif
    @ldx    -1,#        ;-K
    @txs            ;-K set the stack to the top
    @JSR    VICIO        ;-K  go find and do requested operation
bios$exit:
    @sei            ;?K  DISABLE INTERRUPTS
    @ldx    3eh,#        ;?K  set up Z80 memory map as required
    @stx    force$map    ;?K
    @ldx    82h,#        ;-K
    @stx    CIA1+int$ctrl    ;-K  turn on CIA timer B interrupts
  if    use$fast
    @ldx    0,#        ;-K  get value for 1 MHz mode (slow)
    @stx    vic$speed    ;-K  set system speed
  endif
    @jmp    enable$z80+6    ;-K

    PAGE
;
;
;
iotbl:
    dw    sys$reset    ;-1 reset system (C128)
    dw    initilize    ;0 initialize the 8502
    dw    READ        ;1 Read a sector of data to sector buffer
    dw    WRITE        ;2 Write a "     "   "   "    "      "
    dw    readf        ;3 Set-up for fast read (154X only)
    dw    writef        ;4 Set-up for fast write (154X only)
    dw    dsktst        ;5 test for 154x and diskette type
    dw    query$dsk    ;6 get disk characteristics
    dw    PRINT        ;7 print data character
    dw    FORMAT        ;8 format disk as 1541 disk
    dw    user$fun    ;9 vector to user code (L=viccount,H=vicdata)
    dw    ram$dsk$rd    ;10 RAM disk read
    dw    ram$dsk$wr    ;11 RAM disk write


NUMCMD        equ    ($-IOTBL)/2    ; NUMBER OF COMMANDS
iotbl$low    equ    low(iotbl)


;
;
;
sys$reset:            ;**CMD ENTRY**
    @jsr    en$kernal    ;-K
    @JMP    (RESET)        ;+K
;
;
;
user$fun:            ;**CMD ENTRY**
    @jmp    (vic$count)    ;-K

    page
;
; **** IO COMMAND DISPATCH ROUTINE ****
;
VICIO:
    @lda    vic$cmd        ;-K  get the command
    @cmp    NUMCMD,#    ;-K  is this a valid command
    @bcs    bad$command    ;-K  no, exit without doing anything
                ;-K  yes, get vector to it
    @cld            ;-K  clear to binary mode
    @asl    a        ;-K  A=2*CMD (carry cleared)
    @clc            ;-K
    @adc    iotbl$low+2,#    ;-K  add to vector table start address
    @sta    VICIO2+1    ;-K  modify the JMP instructions ind adr
VICIO2:
    @jmp    (IOTBL)        ;-K  this is the ind adr that
                   ; is modified above
;
;
;
input$byte:
    @sei
    @lda    d2pra
    @eor    clk$bit,#
    @sta    d2pra
;
    @lda    8,#
in$1:
    @bit    d1icr
    @beq    in$1
    @lda    d1sdr
bad$command:
    @RTS            ;-K

    page
;
;    initialize the 8502
;
initilize:            ;**CMD ENTRY**
    @ldx    low(irqs),#        ;-K
    @ldy    high(irqs),#        ;-K
    @stx    314h            ;-K  IRQ vector
    @sty    315h            ;-K
    @stx    316h            ;-K  BRK vector
    @sty    317h            ;-K
    @stx    318h            ;-K  NMI vector
    @sty    319h            ;-K

    @jsr    en$kernal        ;-K
    @lda    0fffeh            ;+K
    @sta    0fffeh            ;+K  write to RAM under ROM
    @lda    0ffffh            ;+K
    @sta    0ffffh            ;+K

    @lda    6,#            ;+K
    @sta    CIA2+data$dir$b        ;+K setup user port for RS232

    @lda    pal$nts            ;+K -1=50Hz(PAL) 0=60Hz(NTSC)
    @sta    sys$freq        ;+K
    @jmp    K$clall            ;+K  close all open files

    PAGE
;
; **** DISK SECTOR READ ****
;
READ:                ;**CMD ENTRY**
    @JSR    set$drv        ;-K
    @jsr    en$kernal    ;+K
    @ldx    datchn        ;+K
    @jsr    K$chkin        ;+K
    @bcs    disk$changed    ;+K
    @jsr    K$clrchn    ;+K  clear the input channel for now

    @LDA    '1',#        ;+K  read command
    @JSR    setup        ;+K  send it
    @JSR    CKINDT        ;+K
    @LDX    0,#        ;+K
;
READ1:
    @JSR    K$chrin        ;+K  get a byte from the KERNAL
    @STA    @BUFFER,X    ;+K  save it in the buffer
    @INX            ;+K  advance the buffer pointer
    @BNE    READ1        ;+K  loop back if not past buf end
    @jmp    K$clrchn    ;+K  CLEAR CHANNEL
;
;
disk$changed:
    @lda    0bh,#        ;?K  disk changed error code
    @sta    vic$data    ;?K
    @jmp    en$K$open    ;?K

    page
;
; **** DISK SECTOR WRITE ****
;
WRITE:                ;**CMD ENTRY**
    @jsr    set$drv        ;-K
    @jsr    ckotcm        ;-K
    @LDY    setpnt$lng,#    ;+K
;
WRITE0:
    @LDA    SETPNT,X    ;+K
    @JSR    K$chrout    ;+K
    @INX            ;+K
    @DEY            ;+K
    @BNE    WRITE0        ;+K

    @JSR    K$clrchn    ;+K
    @JSR    CKINCM        ;+K
    @BNE    WRITE2        ;+K

    @JSR    K$clrchn    ;+K
    @JSR    CKOTDT        ;+K
    @LDX    0,#        ;+K
;
WRITE1:
        @sei             ;+K  disable interrupts
    @ldy    3fh,#        ;+K  enable all RAM in bank 0
    @sty    force$map    ;+K
    @LDA    @BUFFER,X    ;-K
    @ldy    0,#        ;-K  re-enable kernal
    @sty    force$map    ;-K
    @JSR    K$chrout    ;+K  write buffer character
    @INX            ;+K
    @BNE    WRITE1        ;+K  write all 256 bytes of buffer

    @JSR    K$clrchn    ;+K  clear the channel
    @LDA    '2',#        ;+K  write command
    @JMP    setup        ;+K
;
WRITE2:
    @lda    0ffh,#        ;+K
    @sta    vic$data    ;+K  writes thru ROM to RAM
    @jmp    opencm        ;+K

    page
;
;    Set-up for fast disk write
;
writef:                ;**CMD ENTRY**
    @lda    2,#        ;-K 2=read command
    @skip2            ;-K
;
;    Set-up for fast disk read
;
readf:                ;**CMD ENTRY**
    @lda    0,#        ;-K 0=read command
    @sta    f$cmd        ;-K
    @lda    0,#        ;-K
    @sta    vic$data    ;-K
    @jsr    set$drv$f    ;-K
    @ldy    f$cmd$lng,#    ;-K  command set above rd/wr
    @jsr    send$fast    ;-K
    @jmp    clk$hi        ;+K

    page
;
;    test the format of the disk return code to CP/M
;    telling the disk type. Also test for FAST disk drive.
;
dsktst:                ;**CMD ENTRY**
    @lda    vic$drv        ;-K
    @eor    0ffh,#        ;-K
    @and    fast        ;-K
    @sta    fast        ;-K  clear fast indicator bit for current drive

    @jsr    set$and$open    ;-K  set drv close and reopen the channel

    @ldx    0,#        ;+K  delay to allow drive to reset status
tst$delay:
    @nop            ;+K
    @nop            ;+K
    @dex            ;+K
    @bne    tst$delay    ;+K

    @ldy    inq$cmd$lng,#    ;+K
    @ldx    inq$cmd,#    ;+K
    @jsr    send$fast$cmd    ;+K

    @jsr    input$byte    ;+K
    @sta    vic$data    ;+K
    @jsr    clk$hi        ;+K
    @sty    io$0        ;+K  2/24
    @lda    vic$drv        ;-K
    @ora    fast        ;-K  set current drive as fast
    @sta    fast        ;-K
    @rts            ;-K

    page
;
;
;
query$dsk:                ;**CMD ENTRY**
    @jsr    set$drv$f        ;-K  will query track set by user
    @ldy    query$cmd$lng,#        ;-K  command length is 4
    @ldx    query$cmd,#        ;-K
    @jsr    send$fast$cmd        ;-K
    @jsr    input$byte        ;+K
    @sta    vic$data        ;+K
    @bpl    clk$hi            ;+K  exit if not MFM
    @and    0eh,#            ;+K  test for error
    @bne    clk$hi            ;+K  exit if error
    @jsr    input$byte        ;+K  read offset sectors status byte
    @sta    @buffer            ;+K
    @and    0eh,#            ;+K  test for error
    @bne    clk$hi            ;+K  exit if error
    @tax                ;+K get a zero in X
    @ldy    5,#            ;+K five info bytes are sent back
query$loop:
    @inx
    @jsr    input$byte
    @sta    @buffer,X
    @dey
    @bne    query$loop

clk$hi:
    @lda    d2pra            ;+K set clock bit HIGH
    @and    0ffh-clkbit,#
    @sta    d2pra
    @rts

    PAGE
;
; **** PRINTER OUTPUT ****
;
;    this routine will support two printers
;    the device number is passed in vic$drv (4,5)
;    secondary address in vic$trk
;    the logical file number is equal to the device #
;    if VIC$count=0 then output character in VIC$data
;    if VIC$count<>0 then output characters pointered to by @buffer
;
PRINT:                ;**CMD ENTRY**
    @lda    vic$drv        ;-K
    @sta    prtno        ;-K
    @lda    vic$trk        ;-K
;;    @sta    second$adr    ;-K  this line should be deleted and one
    @cmp    second$adr    ;-K  ..below used.
    @sta    second$adr    ;-K  save secondary adr
    @bne    reopen$prt    ;-K

    @jsr    en$kernal    ;-K
print$cont:
    @ldx    prtno        ;+K
    @JSR    K$chkout    ;+K
    @BCS    PERR0        ;+K  PRINT ERROR IF CARRY SET

    @sty    io$0        ;+K  2/24
    @ldx    vic$count    ;-K
    @bne    print$buffer    ;-K
    @LDA    vic$data    ;-K  GET CHARACTER
    @sta    io$0        ;-K
    @JSR    K$chrout    ;+K  AND PRINT IT
    @JMP    K$clrchn    ;+K  CLEAR CHANNEL

print$buffer:
    @stx    temp$byte    ;-K
    @lda    @buffer        ;-K
    @sta    adr$1        ;-K
    @lda    @buffer+1    ;-K
    @sta    adr$1+1        ;-K
    @ldy    0,#        ;-K
    @ldx    0,#        ;-K

print$buf$loop:
    @sta    bank$0        ;?K    enable RAM bank 0 (no I/O)
    @lda    (adr$1),y    ;rK
    @stx    force$map    ;rK
    @jsr    K$chrout    ;+K
    @iny            ;+K
    @dec    temp$byte    ;+K
    @bne    print$buf$loop    ;+K
    @jmp    K$clrchn    ;+K

;
;
PERR0:
    @CMP    3,#        ;+K  FILE NOT OPEN?
    @BNE    PERR1        ;+K  BRANCH IF NO
reopen$prt:
    @JSR    OPNPRT        ;?K  OPEN PRINTER CHANNEL
    @BCC    print$cont    ;+K  IF CARRY CLEAR, OK TO PRINT
PERR1:    @LDA    255,#        ;+K  NO DEVICE PRESENT
    @STA    vic$data    ;+K  FLAG BAD ATTEMPT writes to ram under ROM
PRTST:    @RTS            ;+K

    PAGE
;
; **** FORMAT DISK ROUTINE ****
;
FORMAT:                ;**CMD ENTRY**
    @jsr    set$drv$num    ;-K
    @lda    fast        ;-K
    @and    vicdrv        ;-K
    @bne    format$fast    ;-K

    @JSR    CKOTCM        ;-K  returns X=0
    @LDY    fmtcmd$lng,#    ;+K
FMT1:    @LDA    FMTCMD,X    ;+K
    @JSR    K$chrout    ;+K
    @INX            ;+K
    @DEY            ;+K
    @BNE    FMT1        ;+K
    @JSR    K$clrchn    ;+K
fmt2:    @JSR    CKINCM        ;+K check for errors
    @BEQ    setup3        ;+K no errors, return good status
    @BNE    setup5        ;+K error return error status

format$fast:
    @ldx    @buffer        ;-K get command length
fast$F:                ;-K
    @lda    @buffer+1-1,x    ;-K
    @sta    F$cmd-1,x    ;-K
    @dex            ;-K transfer command tail from buffer+1
    @bne    fast$F
    @ldy    @buffer        ;-K
    @iny            ;-K
    @iny            ;-K  count is tail length plus 2
    @ldx    F$cmd        ;-K
    @jsr    send$fast$cmd    ;-K
    @jmp    fmt2        ;+K

    PAGE
;
;
;
ram$dsk$rd:            ; RAM disk read
    @ldx    81h,#            ;-K
    @skip$2                ;-K
;
;
;
ram$dsk$wr:            ; RAM disk write
    @ldx    80h,#            ;-K
  if    use$fast
    @lda    0,#            ;-K  0=slow (1 MHz)
    @sta    vic$speed        ;-K  set to slow mode
  endif
    @lda    3Fh,#
    @stx    RM$command        ;-K  give command to RAM DISK
     @sta    force$map        ;    remove I/O area
    @rts                ;-K


    PAGE
;
;
;
setup:
    @STA    DSKCMD+1    ;?K
    @LDA    2,#        ;?K  RETRY COUNT
    @STA    vic$data    ;?K  writes to RAM under ROM

    @JSR    CKOTCM        ;?K  returns X=0
    @LDY    dskcmd$lng,#    ;+K
setup2:
    @LDA    DSKCMD,X    ;+K
    @JSR    K$chrout    ;+K
    @INX            ;+K
    @DEY            ;+K
    @BNE    setup2        ;+K

    @JSR    K$clrchn    ;+K
    @JSR    CKINCM        ;+K
    @BEQ    setup3        ;+K

    @sty    io$0        ;+K  2/24
    @DEC    vic$data    ;-K
    @BEQ    setup5        ;-K

    @jmp    disk$changed    ;-k
;
;
setup5:
    @LDA    0dh,#        ;?K  normal read/write error flag
    @skip2            ;?K  ALWAYS
;
;
;
setup3:
    @lda    0,#        ;?K  get data good flag
setup4:
    @STA    vic$data    ;?K  writes to RAM under ROM
    @jsr    en$kernal    ;?K
    @JMP    K$clrchn    ;+K

    page
;
;
;
send$fast$cmd:
    @jsr    set$cmd        ;?K  unit # must have been set already
send$fast:
    @ldx    0,#        ;?K
    @stx    force$map    ;?K  enable the kernal
    @ldx    cmdchn        ;+K
    @jsr    K$chkout    ;+K
    @bcs    chan$error    ;+K
    @ldx    0,#        ;+K
sendf:
    @lda    f$cmd$buf,x    ;+K
    @jsr    K$chrout    ;+K
    @inx            ;+K
    @dey            ;+K
    @bne    sendf        ;+K
    @jsr    K$clrchn    ;+K
    @bit    serial        ;+K
    @bvc    not$fast    ;+K
    @bit    d1icr        ;+K  clear interrupts from chip
    @rts            ;+K

chan$error:
    @lda    0dh,#        ;+K  get error code
    @skip2            ;+K
not$fast:
    @lda    0ch,#        ;+K  get error code
    @sta    vic$data    ;+K
    @jsr    clk$hi        ;+K
    @jmp    bios$exit    ;+K
;
;
;
set$cmd:
    @lda    dskcmd+5    ;?K check lsb of unit #
    @ror    a        ;?K get lsb to carry bit
    @bcc    unit$0        ;?K
    @inx            ;?K  make command for unit 1
unit$0:
    @stx    F$cmd        ;?K
    @rts

    page
;
;    ........not tested........
;
;rd$buff:
;    @sei            ; disable interrupts
;    @lda    vic$data
;    @sta    adr$1+1        ; save hi part of address
;    @lda    0,#
;    @sta    adr$1        ; save low part of address
;    @tax            ; get a zero for both indexes
;    @tay
;
;rd$buf$1:
;    @lda    (adr$1),y
;    @sta    @buffer,x
;    @inx
;    @iny
;    @bne    rd$buf$1
;    @rts

    PAGE
;
;
;
set$drv:
    @lda    vic$trk        ;-K
    @jsr    binasc        ;-K
    @stx    dskcmd+7    ;-K
    @sta    dskcmd+8    ;-K

    @lda    vic$sect    ;-K
    @bmi    no$side$1    ;-K
    @jsr    binasc        ;-K
    @stx    dskcmd+10    ;-K
    @sta    dskcmd+11    ;-K
    @jmp    set$drv$num    ;-K

no$side$1:
    @lda    04h,#        ;-K
    @sta    vic$data    ;-K
    @jmp    bios$exit    ;-K

;
;
;
set$drv$f:
    @lda    vic$count    ;-K
    @sta    f$rd$count    ;-K

    @lda    vic$trk        ;-K
    @sta    f$rd$trk

    @lda    vic$sect    ;-K
    @bpl    side$0        ;-K
    @tax            ;-K
    @lda    f$cmd        ;-K
    @ora    10h,#        ;-K
    @sta    f$cmd        ;-K
    @txa            ;-K
    @and    7fh,#        ;-K
side$0:
    @sta    f$rd$sect    ;-K

    page
;
;         VIC$DRV               dev,dat,cmd
;        00000001    device  #8-0     8,11,15
;        00000010    device  #9-0     9,12,16
;        00000100    device #10-0    10,13,17
;        00001000    device #11-0    11,14,18
;        10000001    device  #8-1     8,11,15
;        10000010    device    #9-1     9,12,16
;        10000100    device #10-1    10,13,17
;        10001000    device #11-1    11,14,18
;
set$drv$num:
    @ldy    8-1,#        ;-K start as drive 8
    @ldx    '0',#        ;-K ..unit 0
    @lda    vic$drv        ;-K get requested drv#
    @bpl    unit$nu$0
    @inx            ;-K make unit 1
unit$nu$0:
    @iny            ;-K add one to the drive #
    @lsr    a        ;-K is drive number correct?
    @bcc    unit$nu$0    ;-K no, loop back

    @stx    dskcmd+5    ;-K save unit# to disk cmd string
    @stx    fmtcmd+1    ;-K save unit# to format cmd string
    @txa
    @ror    a        ;-K get lsb to carry bit
    @lda    F$cmd
    @and    0feh,#
    @adc    0,#        ; set the lsb if carry set (carry cleared)
    @sta    F$cmd
    @tya             ;-K get device # to A
    @sta    devno        ;-K save device #
    @adc    3,#        ;-K make the data chan# (carry cleared above)
    @sta    datchn        ;-K save data chan#
    @adc    4,#        ;-K make the cmd chan#
    @sta    cmdchn        ;-K save cmd chan#
    @lda    serial        ;-K
    @and    0bfh,#        ;-K
    @sta    serial        ;-K  clear the fast serial indicator
    @rts            ;-K

    page

;
; **** CONVERT BINARY TO ASCII ****
;
BINASC:
    @CLD            ;?K
    @LDX    '0',#        ;?K
    @SEC            ;?K

BA0:
    @SBC    10,#        ;?K
    @BCC    BA1        ;?K

    @INX            ;?K
    @BCS    BA0        ;?K

BA1:
    @ADC    3Ah,#        ;?K
    @RTS            ;?K

    PAGE
;
; **** OPEN DISK COMMAND CHANNEL ****
;
set$and$open:
    @jsr    set$drv$num    ;-K
en$K$open:
    @jsr    en$kernal    ;-K
opencm:
    @LDA    CMDCHN        ;+K
    @clc            ;+K  clear the carry to force true closing
    @JSR    K$close        ;+K

    @LDA    CMDCHN        ;+K
    @LDX    DEVNO        ;+K
    @LDY    15,#        ;+K
    @JSR    K$setlfs    ;+K

    @lda    0,#        ;+K  bank (C128 type) for load and store
    @sta    F$stat        ;+K  write status byte value = 0
    @tax            ;+K  file name bank (C128 type bank#)
    @jsr    K$setbnk    ;+K

    @ldx    write$stat,#    ;+K
    @jsr    set$cmd        ;+K

    @lda    4,#        ;+K write status command lenght
    @ldx    low(f$cmd$buf),#    ;+K
    @ldy    high(f$cmd$buf),#    ;+K
    @JSR    K$setnam        ;+K

    @JSR    K$open        ;+K
    @bcs    misdsk

    @JSR    K$readst
    @ROL    A        ;+K  GET MSB TO CARRY
    @BCS    MISDSK        ;+K  DEVICE MISSING IF CARRY SET

    @bit    serial        ;+K  test for fast device
    @bvs    no$dt$open    ;+K  do not open data channel if fast
;
; **** OPEN DISK DATA CHANNEL ****
;
OPENDT:
    @LDA    DATCHN        ;+K
    @clc            ;+K  forces true closing of channel
    @JSR    K$close        ;+K
    @LDA    DATCHN        ;+K
    @LDX    DEVNO        ;+K
    @LDY    8,#        ;+K
    @JSR    K$setlfs    ;+K
    @lda    0,#        ;+K  bank (C128 type) for load and store
    @tax            ;+K  file name bank (C128 type bank#)
    @jsr    K$setbnk    ;+K
    @LDA    1,#        ;+K
    @LDX    low(POUND),#    ;+K
    @LDY    high(POUND),#    ;+K
    @JSR    K$setnam    ;+K
    @jsr    K$open        ;+K
    @bcs    misdsk
no$dt$open:
    @rts

    page
;
;
;  * DEVICE MISSING, CLEAN UP ERROR *
;
MISDSK:
    @LDA    0fh,#        ;+K  SET ERROR CODE for missing drive
    @STA    vic$data    ;+K  writes to RAM under ROM
    @LDA    CMDCHN        ;+K  K$close CHANNEL
    @clc            ;+K  force true closing of channel
    @JSR    K$close        ;+K
    @JMP    bios$exit    ;+K

    PAGE
;
; **** SELF CORRECTING CHECK IO ROUTINES ****
;
CKICM:
    @JSR    OPENCM        ;+K

CKINCM:
    @LDX    CMDCHN        ;+K
    @JSR    K$chkin        ;+K
    @BCS    CKICM        ;+K

    @JSR    K$chrin        ;+K
    @CMP    '0',#        ;+K
    @RTS            ;+K
;
;
;
CKIDT:
    @JSR    OPENDT        ;+K
CKINDT:
    @LDX    DATCHN        ;+K
    @JSR    K$chkin        ;+K
    @BCS    CKIDT        ;+K

    @RTS            ;+K
;
;
;
CKODT:
    @JSR    OPENDT        ;+K
CKOTDT:
    @LDX    DATCHN        ;+K
    @JSR    K$chkout    ;+K
    @BCS    CKODT        ;+K

    @RTS            ;+K
;
;
;
CKOCM:
    @jsr    OPENCM        ;+K
CKOTCM:
    @jsr    en$kernal    ;?K
    @LDX    CMDCHN        ;+K
    @JSR    K$chkout    ;+K
    @BCS    CKOCM        ;+K

    @LDX    0,#        ;+K
    @RTS            ;+K

    PAGE
;
; **** OPEN PRINTER CHANNEL ****
;
opnprt:
    @jsr    en$kernal    ;-K
    @lda    prtno        ;+K
    @clc            ;+K
    @JSR    K$close        ;+K

    @lda    prtno        ;+K
    @TAX            ;+K  LDX #4 (or #5)
    @ldy    second$adr    ;+K secondary adr passed in vic$trk (normaly=7)
    @JSR    K$setlfs    ;+K
    @LDA    0,#        ;+K
    @JSR    K$setnam    ;+K
    @lda    0,#        ;+K  bank (C128 type) for load and store
    @tax            ;+K  file name bank (C128 type bank#)
    @jsr    K$setbnk    ;+K
    @JMP    K$open        ;+K

    page
;
;    handle all interrupts in BIOS 8502 (throw them away)
;
irqs:
    @lda    CIA$1+int$ctrl
    @lda    CIA$2+int$ctrl
    @lda    0fh,#
    @sta    VIC+25

    @pla
    @sta    force$map
    @pla
    @tay
    @pla
    @tax
    @pla
    @rti

;
;
;
en$kernal:
    @ldy    0,#        ;?K
    @sty    force$map    ;?K
    @rts            ;+K

    page
;
;
;
DSKCMD:        db    'U1:8 0 tt ss',CR
dskcmd$lng    equ    $-dskcmd

POUND:        db    '#'

FMTCMD:        db    'N0:CP/M DISK,65',CR
fmtcmd$lng    equ     $-FMTCMD

SETPNT:        db    'B-P 8 0',CR
setpnt$lng    equ    $-setpnt
;
;    fast command buffer
;
f$cmd$buf:    db    'U0'    ; not set
f$cmd:        db    0    ; byte 3
F$stat:
f$rd$trk:    db    1    ; byte 4
f$rd$sect:    db    0    ; byte 5
f$rd$count:    db    1    ; byte 6
        db    0    ; byte 7
        db    0    ; byte 8
        db    0    ; byte 9
        db    0    ; byte 10
        db    0    ; byte 11

f$cmd$lng    equ    6        ; U0+cmd+track+sector+#sectors

write$stat    equ    01001100b
write$stat$lng    equ    4        ; U0+cmd+(status to write)

inq$cmd:    equ    00000100b
inq$cmd$lng    equ    3        ; U0+cmd

query$cmd:    equ    10001010b
query$cmd$lng    equ    4        ; U0+cmd+(track offset)