ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/cpm/walnut-creek-CDROM/ENTERPRS/CPM/UTILS/A/28MAY87R.ARK/CXROM02.ASM

Assembly Source File | 1989-09-27 | 7KB | 427 lines

    page
;    *************************************************
;    -                        -
;    -    BIOS8502 code (for read only)        -
;    -                        -
;    *************************************************
;
;    10 May 85
;
;      COMMON EQUATES
;
pointer    equ    20h

datchn    equ    11        ; use data channel #11
cmdchn    equ    15        ; use comand channel #15
;
;    KERNAL EQUATES
;
serial        equ    00A1Ch
D2PRA        equ    0DD00h
D1SDR        equ    0DC0Ch
D1ICR        equ    0DC0Dh
clk$bit        equ    10h


K$set$bnk    equ    0FF68h

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 & SETNAM)
                ;O A = error # (1,2,4,5,6,240)

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

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

K$clall        equ    0FFE7h    ; close all open files

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

K$readst    equ    0FFB7h    ; read status byte
                ;O A = status
    PAGE
;
;
; **** THIS IS THE COMMAND LOOP ****
;
boot$02$code:
    @lda    0,#        ; turn on the kernal
    @sta    force$map    ;
    @jmp    (0fffch)    ; jmp to its start

boot$size    equ    $-boot$02$code

BB    equ    bios$02-$    ; BIOS BIAS

;
bios$65$code:
    @lda    0,#        ;-K
    @sta    vic$data    ;-K
    @JSR    VICIO+BB    ;-K  go find and do requested operation
CMDLP:
    @sei
    @lda    3eh,#        ;?K  set up Z80 memory map as required
    @sta    force$map    ;-K
    @jmp    enable$z80    ;-K

    PAGE
;
;
;
;
; **** IO COMMAND DISPATCH ROUTINE ****
;
VICIO:
    @CLD            ;-K  clear to binary mode
    @LDA    vic$cmd        ;-K  get the command
    @bne    read        ;-K   0=initialize
                ;     1=read
    page
;
;
;
initilize:            ;   initialize the 8502
    @ldx    0,#        ;-K
    @stx    force$map    ;-K  enable the kernal
    @stx    VIC+26        ;+K  turn off VIC interrupts

    @ldx    low(irqs+BB),#
    @ldy    high(irqs+BB),#
    @stx    314h        ;+K  IRQ vector
    @sty    315h
    @stx    316h        ;+K  BRK vector
    @sty    317h
    @stx    318h        ;+K  NMI vector
    @sty    319h
    @jmp    opencm+BB    ;+K  go open channel to disk drive

    PAGE
;
; **** DISK SECTOR READ ****
;
READ:
    @lda    @dma        ;-K
    @sta    pointer        ;-K
    @lda    @dma+1        ;-K
    @sta    pointer+1    ;-K

setdrv:
    @lda    vic$trk        ;-K
    @sta    F$rd$trk+BB    ;-K
    @JSR    BINASC+BB    ;-K
    @STX    dskcmd$T$h+BB    ;-K
    @STA    dskcmd$T$l+BB    ;-K

    @lda    vic$sect    ;-K
    @sta    F$rd$sect+BB    ;-K
    @JSR    BINASC+BB    ;-K
    @STX    dskcmd$S$h+BB    ;-K
    @STA    dskcmd$S$l+BB    ;-K

    @lda    fast        ;-K
    @bne    read$F        ;-K
    @sta    force$map    ;-K A=0 if we did not branch
    @ldx    datchn,#    ;+K
    @jsr    K$chkin        ;+K
    @bcs    disk$changed    ;+K
    @jsr    K$clrchn    ;+K  clear the input channel for now

    @JSR    SETUP+BB    ;+K
    @JSR    CKINDT+BB    ;+K

    @ldy    0,#        ;+K
READ1:
    @JSR    K$chrin        ;+K  get a byte from the KERNAL
    @STA    (pointer),y    ;-K  save it to the DMA pointer
    @iny            ;+K  advance the buffer pointer
    @BNE    READ1        ;+K  loop back if not past buf end
    @jmp    K$clrchn    ;+K  CLEAR CHANNEL


DISK$CHANGED:
    @lda    0FFh,#        ;?K
    @skip2

fst$error:
    @lda    0dh,#
    @sta    vic$data    ;?K
    @jmp    CMDLP+BB

;
;
;
read$F:
    @lda    0,#        ;-K
    @sta    force$map    ;-K
    @ldx    cmdchn,#    ;+K
    @jsr    K$chkout    ;+K
    @bcs    fst$error    ;+K
;    @ldx    0,#        ;+K
    @ldy    Fcmd$lng,#    ;+K
sendf:
    @lda    Fcmd$buf+BB-1,y    ;+K
    @jsr    K$chrout    ;+K
;    @inx
    @dey
    @bne    sendf

    @jsr    K$clrchn    ;+K
    @bit    D1ICR        ;+K
    @ldx    F$rd$count+BB    ;+K
rd$sector:
    @jsr    read$byte+BB    ;+K
    @and    0eh,#        ;+K  mask off error bits
    @bne    fst$error

    @ldy    0,#
rd$buffer:
    @jsr    read$byte+BB    ;+K
    @sta    (pointer),y    ;+K
    @iny            ;+K
    @bne    rd$buffer    ;+K

    @inc    pointer+1    ;+K
    @dex            ;+K
    @bne    rd$sector    ;+K

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

;
;  * DEVICE MISSING, CLEAN UP ERROR *
;
MISDSK:
    @LDA    00fh,#        ;+K  SET ERROR CODE
    @STA    vic$data    ;+K  writes to RAM under ROM
    @JMP    CMDLP+BB    ;+K

    PAGE
;
; **** OPEN DISK COMMAND CHANNEL ****
;
opencm:
    @LDA    cmdchn,#    ;+K
    @CLC            ;+K
    @JSR    K$close        ;+K
    @LDA    cmdchn,#    ;+K
    @sta    fast        ;+K set fast flag
    @LDX    8,#        ;+K
    @TAY            ;+K
    @JSR    K$setlfs    ;+K

    @LDA    0,#        ;+K
    @sta    serial        ;+K clear fast serial indicator
    @TAX            ;+K
    @JSR    K$set$bnk    ;+K

    @LDA    4,#            ;+K
    @LDX    low(U0POINT+BB),#    ;+K
    @LDY    high(U0POINT+BB),#    ;+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

    page
;
; **** OPEN DISK DATA CHANNEL ****
;
OPENDT:
    @LDA    datchn,#    ;+K
    @CLC            ;+K
    @JSR    K$close        ;+K
    @LDA    datchn,#    ;+K
    @LDX    8,#        ;+K
    @LDY    8,#        ;+K
    @JSR    K$setlfs    ;+K

    @LDA    0,#        ;+K
    @sta    fast        ;+K  clear fast flag
    @TAX            ;+K
    @JSR    K$set$bnk    ;+K

    @LDA    1,#            ;+K
    @LDX    low(POUND+BB),#        ;+K
    @LDY    high(POUND+BB),#    ;+K
    @JSR    K$setnam        ;+K
    @JSR    K$open            ;+K
    @bcs    misdsk
no$dt$open:
    @rts

    PAGE
;
;
SETUP:
    @JSR    CKOTCM+BB    ;+K
    @LDY    dskcmd$lng,#    ;+K
SETUP2:
    @LDA    DSKCMD+BB-1,y    ;+K
    @JSR    K$chrout    ;+K
    @DEY            ;+K
    @BNE    SETUP2        ;+K

    @JSR    K$clrchn    ;+K
    @JSR    CKINCM+BB    ;+K
    @BEQ    SETUP3        ;+K

SETUP5:
    @LDA    0dh,#        ;+K  get error flag
    @STA    vic$data    ;+K  writes to RAM under ROM
setup3:
    @JMP    K$clrchn    ;+K


    page
;
;
;
read$byte:
    @sei
    @lda    d2pra
    @eor    clk$bit,#
    @sta    d2pra
    @lda    8,#
in$1:
    @bit    d1icr
    @beq    in$1
    @lda    d1sdr
    @rts


    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

;
;    system saved memory config, Y, X and A before getting here
;
    @pla
    @sta    force$map
    @pla
    @tay
    @pla
    @tax
    @pla
    @rti

;
;
    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
;
; **** SELF CORRECTING CHECK IO ROUTINES ****
;
CKICM:
    @JSR    OPENCM+BB    ;+K
CKINCM:
    @LDX    cmdchn,#    ;+K
    @JSR    K$chkin        ;+K
    @BCS    CKICM        ;+K

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

;
;
;
CKOCM:
    @jsr    OPENCM+BB    ;+K
CKOTCM:
    @LDX    cmdchn,#    ;+K
    @JSR    K$chkout    ;+K
    @BCS    CKOCM        ;+K

    @RTS            ;+K

    PAGE


dskcmd:        db    CR        ;
dskcmd$S$l:    db    's'        ;
dskcmd$S$h:    db    's '        ;
dskcmd$T$l:    db    't'        ;
dskcmd$T$h:    db    't 0 8:1'

U0POINT:    db    'U'    ;
dskcmd$lng    equ    $-DSKCMD
        db    '0',4Ch,0    ; reset disk change status (open)

POUND:        db    '#'

F$cmd$buf:
F$rd$count:    db    1        ; 5 1st read always one sector
F$rd$sect:    db    0        ; 4 filled in
F$rd$trk:    db    0        ; 3 filled in
F$cmd:        db    0        ; 2 read=0
        db    '0U'        ; 1
Fcmd$lng    equ    $-F$cmd$buf

bios$size    equ    $-bios$65$code