CP/M/CPM_CDROM.iso/cpm/c64/tvbios.asm

Assembly Source File | 1984-10-03 | 8.5 KB | 561 lines

;TVBIOS v1.0--add terminal emulation to C64 CP/M
;
;  28 September 1984
;
;  Author:  Ross A.Alford
;           ...{decvax, akgua, ihnp4}!mcnc!ecsvax!alford
;           Compuserve 75475,1404
;
;           Department of Zoology
;           Duke University
;           Durham, NC 27706
;
;  This program is copyrighted 1984 by
;  Ross A. Alford.  Permission is
;  hereby granted for unlimited nonprofit
;  distribution, provided this notice is
;  included.  Permission for any
;  commercial use must be obtained from
;  the author.
;
;  Adds to the C64 BIOS an emulation of
;  the Televideo 920 terminal (in
;  40 columns).
;
;  Takes up the space reserved for 6502
;  BIOS functions 7,8, and 9 at Z80
;  addresses 0fe00h through 0ffffh.
;
;  Also adds auto key repeat after
;  a short delay.
;
;  Using the insert and delete line
;  functions sometimes makes a few
;  characters turn odd colors after they
;  move.  This appears to be due to
;  some sort of a timing problem with
;  the 2114 used for color RAM, and I
;  haven't been able to get around it.
;  I'd like to hear of any solution
;  anyone comes up with.
;
;  This program works with the version
;  of C64 CP/M that I own.  There may
;  be other versions in existance.  If
;  it doesn't work on your system,
;  look up the BIOS locations in your
;  manual and see if they match.
;
;  I make no warranty of this program's
;  usefulness, and assume no liability
;  for any damages it may cause
;  directly or indirectly.
;
;
;  Supports the following commands:
;
;  decimal sequence    function
;
;  26            home and clear
;  27,82        delete line
;  27,69        insert line
;  27,84        erase to end of line
;  27,85        erase to end of screen
;  27,41        inverse video on
;  27,40        inverse video off
;  27,61,row+32,col+32    position cursor
;                         at row, col
;
;
;define true and false
;
true    equ    0ffh
false    equ    00h
;
;
;assemble for 44k or 48k?
;
forty8    equ    true
forty4    equ    false
;
;conditional equates
;
    if    forty8
lastky    equ    0ba63h
j9    equ    0bbd5h
const1    equ    0bbd7h
const2    equ    0bbdch
conout    equ    0bc76h
j20    equ    0bc7ch
cout1    equ    0bc89h
cout5    equ    0bcaah
    endif
;
    if    forty4
lastky    equ    0aa63h
j9    equ    0abd5h
const1    equ    0abd7h
const2    equ    0abdch
conout    equ    0ac76h
j20    equ    0ac7ch
cout1    equ    0ac89h
cout5    equ    0acaah
    endif
;
;global equates
;
cr    equ    00dh
lf    equ    00ah
offset    equ    0fb00h
iotype    equ    0fcffh
chrst    equ    0f400h
colst    equ    0c800h
chrend    equ    0f7bfh
colend    equ    0cbbfh
color    equ    0f286h
row6502    equ    0f0d6h
col6502    equ    0f0d3h
bdos    equ    0005h
prtstr    equ    009h
data6502 equ    0f901h
rvs6502    equ    0f0c7h;
jrnz    equ    020h
;
;routine that relocates the
;  tvbios routines into the
;  extra 512 bytes at 0fe00h
;  and patches conout in the
;  bios to jump to tvbios
;
    org    0100h
    lxi    d,msg1
    mvi    c,prtstr
    call    bdos
    lxi    b,tvbios
    lxi    h,scend-tvbios
    lxi    d,0fe00h
    call    movup
    lxi    b,bpatch
    lxi    d,conout
    lxi    h,0003h
    call    movup
    lxi    b,bpatch2
    lxi    d,j9-1
    lxi    h,0003h
    call    movup
    lxi    b,bpatch3
    lxi    d,cout5
    lxi    h,0003h
    call    movup
    ret
movup:    ldax    b
    stax    d
    inx    b
    inx    d
    dcx    h
    xra    a
    cmp    h
    jnz    movup
    cmp    l
    jnz    movup
    ret
;
;
;jump to tvbios to patch into
;  bios80 at conout start
;
;
bpatch    jmp    0fe00h
;
;
;patch to jump for keyboard
;  auto repeat.  inserted into
;  BIOS80 at j9-1, which should
;  be CMP M
;
;
bpatch2: jmp    rptpat+offset
;
;
;jump to routine to check and
;  correct inverse/normal video
;  status.   inserted into the
;  BIOS at location cout5
;
;
bpatch3: jmp    invpat+offset
;
;
;startup messages
;
msg1    db    cr,lf,'TVBIOS v1.0 for C64 CP/M',cr,lf
    db    'Emulates the TVI 920 in 40 columns',cr,lf,cr,lf
    db    'Copyright 1984 by Ross A. Alford',cr,lf
    db    'All commercial rights reserved',cr,lf,cr,lf,'$'
;
;
;main TVBIOS interpreter
;
;
    org    0300h
tvbios    lda    flag+offset
    db    0cbh,07fh
;    bit    7,a
     jnz    esced+offset
    db    0cbh,047h
;    bit    0,a
    jnz    curdo+offset
    mov    a,c
    cpi    01bh    ;esc?
    jnz    ccz+offset
    mvi    a,true
    sta    flag+offset
    ret
ccz:    cpi    01ah
    jnz    endscop+offset
    mvi    a,0ch
    mov    c,a
endscop: lda    iotype
    ani    010h
    mov    a,c
    jnz    cout5
    jmp    j20+02h
esced:    xra    a
    sta    flag+offset
    mov    a,c
    cpi    052h
    jz    delrow+offset
    cpi    045h
    jz    insrow+offset
    cpi    054h
    jz    clreol+offset
    cpi    055h
    jz    clreos+offset
    cpi    029h
    jz    invon+offset
    cpi    028h
    jz    invoff+offset
    cpi    03dh
    rnz
    mvi    a,01h
    sta    flag+offset
    ret
curdo:    db    0cbh,04fh
;    bit    1,a
    jnz    curcol+offset
    mov    a,c
    sui    020h
    sta    row+offset
    mvi    a,03h
    sta    flag+offset
    ret
curcol:    xra    a
    sta    flag+offset
    mov    a,c
    sui    020h
    sta    col+offset
    jmp    curpos+offset
;
;subroutine insrow: insert a blank
;  line at the row given by row
;
insrow: call    stindl+offset
    push    h
    lxi    b,chrend
    lxi     d,chrend+028h
    call    lddr+offset
    pop    h
    lxi    b,colend
    lxi    d,colend+028h
    call    lddr+offset
    mvi    a,028h
    sta    ntoblk+offset
;
;subroutine blank: change 'ntoblk'
;  positions to blank starting at
;  current chradr, coladr
;
blank:    mvi    b,020h
    lda    ntoblk+offset
    lhld    chradr+offset
blank1:    mov    m,b
    inx    h
    dcr    a
    ora    a
    jnz    blank1+offset
    mvi    b,0f6h
    lda    ntoblk+offset
    lhld    coladr+offset
blank2:    mov    m,b
    inx    h
    dcr    a
    ora    a
    jnz    blank2+offset
    ret
;
;
;subroutine saverc: moves row
;  and col numbers from 6502
;  locs to tvbios locs
;
;
saverc:    lda    col6502
    sta    col+offset
    lda    row6502
    sta    row+offset
    ret
;
;subroutine calcstnd:  calculate
;  addresses for start of color
;  and char memory given a row #
;  row passed in 'row', addresses
;  returned in coladr, chradr
;
calcstnd: lda    row+offset
    ani    07fh
    lxi    h,0000h
    lxi    b,0000h
    ora    a
    jz    caend+offset
    lxi    b,0028h
calclp:    ora    a
    jz    caend+offset
    dad    b
    dcr    a
    jmp    calclp+offset
caend:    push    h
    lxi    b,chrst
    dad    b
    shld    chradr+offset
    pop    h
    lxi    b,colst
    dad    b
    shld    coladr+offset
    ret
;
;
;subroutine lddr: simulate the
;  lddr instruction, sort of
;  pass from in bc, to in de,
;  number in hl
;  this is used rather than the
;  real thing because lddr is
;  apparently too fast for
;  the color memory
;
;
lddr:    ldax    b
    push    h    ;delay
    pop    h    ;delay
    stax    d
    dcx    b
    dcx    d
    dcx    h
    xra    a
    cmp    h
lddr1:    db    jrnz,(lddr-lddr1-2) and 0ffh
    cmp    l
lddr2:    db    jrnz,(lddr-lddr2-2) and 0ffh
    ret
;
;subroutine ldir: move byte
;  pointed to by bc to loc
;  pointed to by de, inc bc, de
;  repeat hl times
;
ldir    ldax    b
    push    h    ;delay
    pop    h    ;delay
    stax    d
    inx    b
    inx    d
    dcx    h
    xra    a
    cmp    h
ldir1:    db    jrnz,(ldir-ldir1-2) and 0ffh
    cmp    l
ldir2:    db    jrnz,(ldir-ldir2-2) and 0ffh
    ret
;
;
;subroutine clreol:clear to end
;  of current screen line
;
;
clreol:    call    saverc+offset
ceol2:    call    calcstnd+offset
    lxi    h,col+offset
    mvi    a,028h
    sub    m
    sta    ntoblk+offset
    mvi    b,0
    lda    col+offset
    mov    c,a
    lhld    chradr+offset
    dad    b
    shld    chradr+offset
    lhld    coladr+offset
    dad    b
    shld    coladr+offset
    call    blank+offset
    ret
;
;
;subroutine clreos:clear from
;  cursor to end of page
;
;
clreos:    call    clreol+offset
    xra    a
    sta    col+offset
ceop2:    lxi    h,row+offset
    inr    m
    mvi    a,018h
    cmp    m
    jc    ceopnd+offset
    call    ceol2+offset
    jmp    ceop2+offset
ceopnd:    ret
;
;
;subroutine curpos: position
;  cursor on coords passed in
;  locations row and col
;
;
curpos:    lda    row+offset
    ani    07fh
    cpi    019h
    rnc
    dcr    a
    sta    row6502
    mvi    a,0dh
    call    cout5
    lda    col+offset
    ani    07fh
    cpi    028h
    rnc
    sta    col6502
    ret
;
;
;subroutine invon:start inverse
;
;
invon:    mvi    a,01h
    sta    invflg+offset
    ret
;
;
;subroutine invoff: end inverse
;
;
invoff:    xra    a
    sta    invflg+offset
    ret
;
;subroutine delrow: delete the
;  row pointed to by row
;
delrow: call    stindl+offset
    push    h
    push    h
    lxi    h,0028h
    dad    d
    mov    b,h
    mov    c,l
    pop    h
    call    ldir+offset
    lhld    coladr+offset
    mov    d,h
    mov    e,l
    lxi    h,0028h
    dad    d
    mov    b,h
    mov    c,l
    pop    h
    call    ldir+offset
lastrw:    xra    a
    sta    col+offset
    mvi    a,018h
    sta    row+offset
    call    ceol2+offset
    ret
;
;subroutine stindl: startup
;  for insert/delete a row
;  routines.  exit with chradr
;  in d,e and chrend-chradr in
;  hl
;
stindl:    call    saverc+offset
    ani    07fh
    cpi    018h
    jc    stin2+offset
    pop    h    ;last return address
    jmp    lastrw+offset
stin2:        call    calcstnd+offset
    xra    a
    lhld    chradr+offset
    mov    d,h
    mov    e,l
    lxi    h,chrend
    db    0edh,052h
;    sbc    hl,de
    inx    h
    ret
;
;
;rptpat routine: a jump to this
;  is inserted at j9-1 in the
;  BIOS.   This repeats any
;  keypress after a delay
;
;
rptpat:    mov    b,a
    cpi    040h
    jnz    rpp1+offset
    sta    lastky
    jmp    const1
rpp1:    cmp    m
    jz    rpp2+offset
    mvi    a,080h
    sta    delay+offset
    mov    a,b
    jmp    const2
rpp2:    lxi    h,delay+offset
    dcr    m
    jnz    const1
    mvi    a,018h
    mov    m,a
    mov    a,b
    jmp    const2
;
;
;routine invpat is jumped to
;  by the modified BIOS from
;  location COUT5.  it fixes
;  the inverse/normal status,
;  then continues as normal
;
;
invpat: mov    b,a
    lda    invflg+offset
    sta    rvs6502
    mov    a,b
    sta    data6502
    jmp    cout5+3
;
;storage locations
;
row    db    0
col    db    0
chradr    db    0,0
coladr    db    0,0
ntoblk    db    0
flag    db    0
delay    db    080h
invflg    db    0
;
scend    end