Oakland CPM Archive/oakcpm.iso/sigm/vol167/vgr.asm

Assembly Source File | 1984-04-29 | 15.0 KB | 1,469 lines

msk:    equ    00CC9H
wy:    equ    00CCAH    ;wy,ex form a double byte in this order
ex:    equ    00CCBH
wye:    equ    00CCCH
eks:    equ    00CCDH
ssiz:    equ    02000H
rsiz:    equ    040H
sorg:    equ    04000H

    org    0100H
    jmp gdem


;    point mode: move cursor right

pxpl:    lxi h,msk
    mov a,m
    ani 0AAH
    jz  pxp1
    rrc
    mov m,a
    ret
pxp1:    mov a,m
    rrc
    rrc
    rrc
    mov m,a
    ani 0A0H
    rz
    lda ex
    adi 004H
    sta ex
    ret

;    point mode: move cursor left

pxmi:    lxi h,msk
    mov a,m
    ani 055H
    jz  pxm1
    rlc
    mov m,a
    ret
pxm1:    mov a,m
    rlc
    rlc
    rlc
    mov m,a
    ani 005H
    rz
    lda ex
    sui 004H
    sta ex
    ret

;    point mode: move cursor up

pypl:    lxi h,msk
    mov a,m
    ani 033H
    jz  pyp1
    rlc
    rlc
    mov m,a
    ret
pyp1:    mov a,m
    rrc
    rrc
    mov m,a
    lda wy
    sui 002H
    sta wy
    ret

;    point mode: move cursor down

pymi:    lxi h,msk
    mov a,m
    ani 0CCH
    jz  pym1
    rrc
    rrc
    mov m,a
    ret
pym1    mov a,m
    rlc
    rlc
    mov m,a
    lda wy
    adi 002H
    sta wy
    ret

;    load acc with mask, HL with byte address from
;    (msk,wy,ex)

dot:    lhld wy
    mov a,h
    mvi h,sorg/02000H
    dad h
    dad h
    dad h
    dad h
    dad h
    rrc
    rrc
    ora l
    mov l,a
    lda msk
    ret

;    point mode: home cursor

phom:    lxi h,08080H
    shld wy
    mvi a,040H
    sta msk
    ret

;    point mode: make white dot at cursor

pwhit:    call dot
    ora m
    mov m,a
    ret

;    point mode: make black dot at cursor

pblak:    call dot
    cma
    ana m
    mov m,a
    ret

;    point mode: reverse dot under cursor

prev:    call dot
    xra m
    mov m,a
    ret

;    point mode: test dot under cursor

ptest:    call dot
    ana m
    ret

;    both modes: clear screen to white

whit:    lxi d,ssiz
    lxi h,sorg
whi1:    mvi m,0FFH
    inx h
    dcr e
    jnz whi1
    dcr d
    jnz whi1
    ret

;    both modes: clear screen to black

blak:    lxi d,ssiz
    lxi h,sorg
bla1:    mvi m,000H
    inx h
    dcr e
    jnz bla1
    dcr d
    jnz bla1
    ret

;    both modes: reverse entire screen

reve:    lxi d,ssiz
    lxi h,sorg
rev1:    mov a,m
    xri 0FFH
    mov m,a
    inx h
    dcr e
    jnz rev1
    dcr d
    jnz rev1
    ret

;    point mode:    given a cartesian address, form a bit
;    mask and byte address for the cursor

pcar:    lhld wye
    mvi b,001H
    mov a,h
    rrc
    jnc pca1
    mov h,a
    mov a,b
    rlc
    mov b,a
    mov a,h
pca1:    rrc
    jnc pca2
    mov a,b
    rlc
    rlc
    rlc
    rlc
    mov b,a
pca2:    mov a,l
    rrc
    mov b,a
    jnc pca3
    rlc
    rlc
pca3:    sta msk
    lda wye
    ani 0FCH
    sta wy
    lda eks
    ani 0FEH
    sta wy
    ret

;    point mode:  draw a line between two points
;    given the increments (B,C)=(dx,dy)

plin:    lxi h,pxpl
    mov a,b
    ora a
    jp  pli1
    cma
    inr a
    mov b,a
    lxi h,pxmi
pli1:    lxi d,pypl
    mov a,c
    ora a
    jp  pli2
    cma
    inr a
    mov c,a
    lxi d,pymi
pli2:    cmp b
    jnc pli3
    xchg
    mov c,b
    mov b,a
pli3:    mov a,c
    sta eks
    mov a,b
    add a
    mov b,a
    sub c
    push psw
    sub c
    mov c,a
pli4:    pop psw
    push h
    lxi h,prev
    xthl
    cpi 001H
    jm  pli5
    push h
    add c
    jmp pli6
pli5:    add b
pli6:    push d
    push psw
    lda eks
    dcr a
    sta eks
    jnz pli4
    pop psw
    ret

;    point mode: shift within one byte to scroll the
;    screen right one pixel

pexpl:    mov a,m
    rrc
    mov b,a
    ani 055H
    ora c
    mov c,a
    mov a,b
    rrc
    rrc
    mov b,a
    ani 00AH
    ora c
    mov c,a
    mov a,b
    ani 0A0H
    mov b,c
    mov c,a
    ret

;    point mode: intra-byte shift to scroll left one pixel

pexmi:    mov a,m
    rlc
    mov b,a
    ani 0AAH
    ora c
    mov c,a
    mov a,b
    rlc
    rlc
    mov b,a
    ani 050H
    ora c
    mov c,a
    mov a,b
    ani 005H
    mov b,c
    mov c,a
    ret

;    point mode: intrabyte shift to scroll up one pixel

pwypl:    mov a,m
    mov b,a
    rlc
    rlc
    ani 0CCH
    ora c
    mov c,a
    mov a,b
    ani 0CCH
    rrc
    rrc
    mov b,c
    mov c,a
    ret

;    point mode: intrabyte shift to scroll down one pixel

pwymi:    mov a,m
    mov b,a
    rrc
    rrc
    ani 033H
    ora c
    mov c,a
    mov a,b
    ani 033H
    rlc
    rlc
    mov b,c
    mov c,a
    ret

;    point mode: move entire screen right one pixel

pekspl:    lxi h,sorg
    lxi d,rsiz-1
peksp1:    push h
    dad d
    call pexpl
    pop h
peksp2:    call pexpl
    mov m,b
    inx h
    mov a,l
    ani 03FH
    jnz peksp2
    mov a,h
    cpi (sorg+ssiz)/0100H
    jnz peksp1
    ret

;    point mode: shift entire screen left one pixel

peksmi:    lxi h,sorg+ssiz-1
    lxi d,-rsiz+1
peksm1:    push h
    dad d
    call pexmi
    pop h
peksm2:    call pexmi
    mov m,b
    mov a,l
    ani 03FH
    dcx h
    jnz peksm2
    mov a,h
    cpi sorg/0100H-1
    jnz peksm1
    ret

;    point mode: shift entire screen up one pixel

pwyepl:    lxi h,sorg+ssiz-1
pwyep1:    lxi d,-ssiz+rsiz
    push h
    dad d
    call pwypl
    pop h
    push h
    lxi d,-rsiz
pwyep2:    call pwypl
    mov m,b
    dad d
    mov a,h
    cpi sorg/0100H-1
    jnz pwyep2
    pop h
    mov a,l
    ani 03FH
    dcx h
    jnz pwyep1
    ret

;    point mode: move entire screen down one pixel

pwyemi:    lxi h,sorg
pwyem1:    lxi d,ssiz-rsiz
    push h
    dad d
    call pwymi
    pop h
    push h
    lxi d,rsiz
pwyem2:    call pwymi
    mov m,b
    dad d
    mov a,h
    cpi (sorg+ssiz)/0100H
    jnz pwyem2
    pop h
    inx h
    mov a,l
    ani 03FH
    jnz pwyem1
    ret

;    fast right shift of 4 pixels= 1 byte

fxpl:    lxi h,sorg
    lxi d,rsiz-1
fxp1:    push h
    dad d
    mov b,m
    pop h
fxp2:    mov a,m
    mov m,b
    mov b,a
    inx h
    mov a,l
    ani 03FH
    jnz fxp2
    mov a,h
    cpi (sorg+ssiz)/0100H
    jnz fxp1
    ret

;    fast left shift of 4 pixels which is one byte

fxmi:    lxi h,sorg+ssiz-1
    lxi d,-rsiz+1
fxm1:    push h
    dad d
    mov b,m
    pop h
fxm2:    mov a,m
    mov m,b
    mov b,a
    mov a,l
    ani 03FH
    dcx h
    jnz fxm2
    mov a,h
    cpi sorg/0100H-1
    jnz fxm1
    ret

;    fast shift up by 2 pixels = 1 byte

fypl:    lxi h,sorg+ssiz-1
fyp1:    lxi d,-ssiz+rsiz
    push h
    dad d
    mov b,m
    pop h
    push h
    lxi d,-rsiz
fyp2:    mov a,m
    mov m,b
    mov b,a
    dad d
    mov a,h
    cpi sorg/0100H-1
    jnz fyp2
    pop h
    mov a,l
    ani 03FH
    dcx h
    jnz fyp1
    ret

;    fast down shift of entire screen by 2 pixels = 1 byte

fymi:    lxi h,sorg
fym1:    lxi d,ssiz-rsiz
    push h
    dad d
    mov b,m
    pop h
    push h
    lxi d,rsiz
fym2:    mov a,m
    mov m,b
    mov b,a
    dad d
    mov a,h
    cpi (sorg+ssiz)/0100H
    jnz fym2
    pop h
    inx h
    mov a,l
    ani 03FH
    jnz fym1
    ret

;    gray mode: in-byte right shift

gexpl:    mov a,m
    rrc
    rrc
    rrc
    rrc
    mov b,a
    ani 00FH
    ora c
    mov c,a
    mov a,b
    ani 0F0H
    mov b,c
    mov c,a
    ret

;    gray mode: intrabyte left shift of one pixel

gexmi:    mov a,m
    rlc
    rlc
    rlc
    rlc
    mov b,a
    ani 0E0H
    ora c
    mov c,a
    mov a,b
    ani 00FH
    mov b,c
    mov c,a
    ret

;    gray mode: shift whole screen 1 pixel right

gekspl:    lxi h,sorg
    lxi d,rsiz-1
geksp1:    push h
    dad d
    call gexpl
    pop h
geksp2:    call gexpl
    mov m,b
    inx h
    mov a,l
    ani 03FH
    jnz geksp2
    mov a,h
    cpi (sorg+ssiz)/0100H
    jnz geksp1
    ret

;    gray mode: shift entire screen left one pixel

geksmi:    lxi h,sorg+ssiz-1
    lxi d,-rsiz+1
geksm1:    push h
    dad d
    call gexmi
    pop h
geksm2:    call gexmi
    mov m,b
    mov a,l
    ani 03FH
    dcx h
    jnz geksm2
    mov a,h
    cpi sorg/0100H-1
    jnz geksm1
    ret

;    gray mode: move cursor right one pixel

gxpl:    lxi h,msk
    mov a,m
    ani 0F0H
    jz  gxp1
    mvi m,00FH
    ret
gxp1:    mvi m,0F0H
    lda ex
    adi 004H
    sta ex
    ret

;    gray mode: shift cursor left one pixel

gxmi:    lxi h,msk
    mov a,m
    ani 00FH
    jz  gxm1
    mvi m,0F0H
    ret
gxm1:    mvi m,00FH
    lda ex
    sui 004H
    sta ex
    ret

;    gray mode: move cursor up one pixel

gypl:    lda wy
    sui 002H
    sta wy
    ret

;    gray mode: move cursor down one pixel

gymi:    lda wy
    adi 002H
    sta wy
    ret

;    gray mode: home cursor

ghom:    lxi h,08080H
    shld wy
    mvi a,00FH
    sta msk
    ret

;    gray mode: make cursor pixel white

gwhi:    call dot
    ora m
    mov m,a
    ret

;    gray mode: make cursor pixel black

gbla:    call dot
    cma
    ana m
    mov m,a
    ret

;    gray mode: reverse cursor pixel

grev:    call dot
    xra m
    mov m,a
    ret

;    gray mode: sense cursor pixel

gsen:    call dot
    ana m
    rz
    push psw
    ani 0F0H
    pop psw
    rz
    rrc
    rrc
    rrc
    rrc
    ret

;    gray mode: raise gray level of cursor pixel

gzpl:    call dot
    mov b,a
    cma
    ana m
    mov c,a
    mov a,b
    ana m
    adi 011H
    ana b
    ora c
    mov m,a
    ret

;    gray mode: lower pixel under cursor one gray level

gzmi:    call dot
    mov b,a
    cma
    ana m
    mov c,a
    mov a,b
    ana m
    adi 0FFH
    ana b
    ora c
    mov m,a
    ret

;    gray mode: cartesian coordinates to mask, byte address

gcart:    lhld wye
    mov a,l
    ani 03FH
    rlc
    sta wy
    mov a,h
    ani 03FH
    rrc
    push psw
    rlc
    rlc
    rlc
    sta ex
    pop psw
    mvi a,00FH
    jc  gcar1
    xri 0FFH
gcar1:    sta msk
    ret

;    form decimal number from digit string

nure:    mvi b,000H
nur1:    call read
    cpi '-'
    jz  numi
    cpi '0'
    rc
    cpi ':'
    rnc
    sui '0'
    mov c,a
    mov a,b
    rlc
    rlc
    add b
    rlc
    add c
    mov b,a
    jmp nur1
numi:    lxi h,minu
    push h
    jmp nur1
minu:    push psw
    mov a,b
    cma
    inr a
    mov b,a
    pop psw
    ret

;    get (B,C)=(count, operation)

coop:    call nure
    mov c,a
    mov a,b
    ora a
    rnz
    mvi b,001H
    ret

;    get (B,C)=(x,y)

coor:    call nure
    push b
    call nure
    pop psw
    mov c,b
    mov b,a
    ret

;    repeat the subroutine in (HL) (B) times

iter:    push b
    mov a,c
    push h
    lxi d,ite1
    push d
    pchl
ite1:    pop h
    pop b
    dcr b
    rz
    jmp iter

    nop
    nop

;    block of combined cursor movements and cursor
;    inversions in the point mode - for demonstration

pn:    call prev
    call pypl
    jmp  prev

ps:    call prev
    call pymi
    jmp  prev

pe:    call prev
    call pxpl
    jmp  prev

pw:    call prev
    call pxmi
    jmp  prev

;    place the individual negatives of the bytes B,C in H,L

negl:    mov a,c
    cma
    inr a
    mov l,a
    mov a,b
    cma
    inr a
    mov h,a
    ret

;    add D,E to H,L as two separate bytes, sum in H,L

addl:    mov a,e
    add l
    mov l,a
    mov a,d
    add h
    mov h,a
    ret

;    command i reads increment pair, plots line

pii:    call coor
    jmp  plin

;    command t reads two adjacent edges, plots triangle

tt:    call coor
    call negl
    push h
    push b
    call coor
    call negl
    pop d
    call addl
    push h
    call plin
    pop b
    call plin
    pop b
    jmp  plin

;    command p reads cartesian coordinates, plots point

pp:    call coor
    mov a,b
    adi 080H
    sta eks
    mov a,c
    cma
    adi 081H
    sta wye
    call pcar
    jmp  prev

;    block of combined screen-cursor shifts

pea:    call pekspl
    jmp  pxpl

pwe:    call peksmi
    jmp  pxmi

pno:    call pwyepl
    jmp  pypl

pso:    call pwyemi
    jmp  pymi

;    similar block for grey mode

gea:    call gekspl
    jmp  gxpl

gwe:    call geksmi
    jmp  gxmi

gno:    call fypl
    jmp  gypl

gso:    call fymi
    jmp  gymi

;    combined cursor movement and 8-level gray shift

ge:    call gzeh
    call gxpl
    jmp  gzeh

gw:    call gzeh
    call gxmi
    jmp  gzeh

gn:    call gzeh
    call gypl
    jmp  gzeh

gs:    call gzeh
    call gymi
    jmp  gzeh

;    move whole screen through 8 gray points

gzeeh:    lxi d,ssiz
    lxi h,sorg
gzee1:    mov b,m
    mov a,b
    ani 0F0H
    mov c,a
    mov a,b
    adi 008H
    ani 00FH
    ora c
    adi 080H
    mov m,a
    inx h
    dcr e
    jnz gzee1
    dcr d
    jnz gzee1
    ret

;    lighten the whole screen by one grey point

gzeepl:    lxi d,ssiz
    lxi h,sorg
gzeep1:    mov b,m
    mov a,b
    ani 0F0H
    mov c,a
    mov a,b
    adi 001H
    ani 00FH
    ora c
    adi 010H
    mov m,a
    inx h
    dcr e
    jnz gzeep1
    dcr d
    jnz gzeep1
    ret

;    darken whole screen by one gray point

gzeemi:    lxi d,ssiz
    lxi h,sorg
gzeem1:    mov b,m
    mov a,b
    ani 0F0H
    mov c,a
    mov a,b
    adi 00FH
    ani 00FH
    ora c
    adi 0F0H
    mov m,a
    inx h
    dcr e
    jnz gzeem1
    dcr d
    jnz gzeem1
    ret

;    lighten the pixel under the cursor by 8 points

gzeh:    call dot
gzed:    mov c,a
    cma
    ana m
    mov b,a
    mov a,m
    ana c
    adi 088H
    ana c
    ora b
    mov m,a
    ret

;    lighten all pixels from here to left margin 8 points

edge:    call dot
    ora a
    jp edg1
    call gzed
edg1:    mov a,l
    ani 03FH
    rz
    dcx h
    mov b,m
    mov a,b
    ani 0F0H
    mov c,a
    mov a,b
    sui 008H
    ani 00FH
    ora c
    sui 080H
    mov m,a
    jmp edg1

;    block of combined cursor movements and pixel reverses

gee:    call gxpl
    jmp  gzeh

gww:    call gxmi
    jmp  gzeh

gnn:    call gypl
    jmp  gzeh

gss:    call gymi
    jmp  gzeh

;    draw a line with given increments in grey mode

glin:    lxi h,gxpl
    mov a,b
    ora a
    jp gli1
    cma
    inr a
    mov b,a
    lxi h,gxmi
gli1:    lxi d,gypl
    mov a,c
    ora a
    jp gli2
    cma
    inr a
    mov c,a
    lxi d,gymi
gli2:    cmp b
    jnc gli3
    xchg
    mov c,b
    mov b,a
gli3:    mov a,c
    sta eks
    mov a,b
    add a
    mov b,a
    sub c
    push psw
    sub c
    mov c,a
gli4:    pop psw
    push h
    lxi h,gzeh
    xthl
    cpi 001H
    jm gli5
    push h
    add c
    jmp gli6
gli5:    add b
gli6:    push d
    push psw
    lda eks
    dcr a
    sta eks
    jnz gli4
    pop psw
    ret

;    draw a shaded triangle

shat:    call coor
    call negl
    push h
    push b
    call coor
    call negl
    pop d
    call addl
    push h
    call glin
    call edge
    pop b
    call glin
    call edge
    pop b
    jmp  glin

;    - - -  LIFE in the gray mode - - -



;    ordinary cycle for neighbors of left pixel

olep:    push h
    push h
    dad d
    mov a,m
    adi 011H
    mov m,a
    dcx h
    inr m
    pop h
    dcx h
    inr m
    dad b
    inr m
    inx h
    mov a,m
    adi 011H
    mov m,a
    pop h
    ret

;    ordinary cycle for neighbors of right pixel

orip:    push h
    push h
    dad d
    mov a,m
    adi 011H
    mov m,a
    inx h
    mov a,m
    adi 010H
    mov m,a
    pop h
    inx h
    mov a,m
    adi 010H
    mov m,a
    dad b
    mov a,m
    adi 010H
    mov m,a
    dcx h
    mov a,m
    adi 011H
    mov m,a
    pop h
    ret

;    count neighbors of ordinary cells

onec:    lxi b,rsiz
    lxi d,-rsiz
    lxi h,sorg+rsiz
one1:    mov a,m
    ani 080H
    cnz rnom
    mov a,m
    ani 008H
    cnz lnom
    inx h
    mov a,l
    cpi 0C0H
    jnz one1
    mov a,h
    cpi (sorg+ssiz)/0100H-1
    jnz one1
    ret

;    update to next generation once neighbor count done

next:    lxi d,ssiz
    lxi h,sorg
nex1:    mov a,m
    ora a
    jz nex8
    mov c,a
    ani 077H
    mov b,a
    mov a,c
    ani 088H
    mov c,a
    rlc
    add b
    mov b,a
    push h
    lxi h,nex4
    xthl
    mov a,b
    ani 0F0H
    cpi 020H
    jz nex2
    cpi 030H
    jz nex3
    xra a
    ret
nex2:    mov a,c
    ani 080H
    ret
nex3:    mvi a,080H
    ret
nex4:    push psw
    push h
    lxi h,nex7
    xthl
    mov a,b
    ani 00FH
    cpi 002H
    jz nex5
    cpi 003H
    jz nex6
    xra a
    ret
nex5:    mov a,c
    ani 008H
    ret
nex6:    mvi a,008H
    ret
nex7:    pop b
    ora b
    mov m,a
nex8:    inx h
    dcr e
    jnz nex1
    dcr d
    jnz nex1
    ret

;    cycle for left pixel on left margin

llep:    push h
    push h
    push h
    dad d
    mov a,m
    adi 011H
    mov m,a
    mov a,l
    ori 03FH
    mov l,a
    inr m
    pop h
    mov a,l
    ori 03FH
    mov l,a
    inr m
    dad b
    inr m
    pop h
    dad b
    mov a,m
    adi 011H
    mov m,a
    pop h
    ret

;    cycle for right pixel on right margin

rrip:    push h
    push h
    push h
    dad d
    mov a,m
    adi 011H
    mov m,a
    mov a,l
    ani 0C0H
    mov l,a
    mov a,m
    adi 010H
    mov m,a
    pop h
    mov a,l
    ani 0C0H
    mov l,a
    mov a,m
    adi 010H
    mov m,a
    dad b
    mov a,m
    adi 010H
    mov m,a
    pop h
    dad b
    mov a,m
    adi 011H
    mov m,a
    pop h
    ret

;    left pixel: choose between normal or margin cycle

rnom:    mov a,l
    ani 03FH
    jz  llep
    jmp olep

;    right pixel: chose normal or margin cycle

lnom:    mov a,l
    ani 03FH
    cpi 03FH
    jz  rrip
    jmp orip

;    count neighbors along top margin

ncto:    lxi b,rsiz
    lxi d,ssiz-rsiz
    lxi h,sorg
ncti:    mov a,m
    ani 080H
    cnz rnom
    mov a,m
    ani 008H
    cnz lnom
    inx h
    mov a,l
    ani 03FH
    jnz ncti
    ret

;    count neighbors along bottom margin

ncbo:    lxi b,-ssiz+rsiz
    lxi d,-rsiz
    lxi h,sorg+ssiz-rsiz
    jmp ncti

;    execute one cycle of LIFE

life:    call onec
    call ncto
    call ncbo
    jmp next

;    demonstration for point mode graphics

pdem:    call phom
pden:    call coop
    lxi h,pvec
    call iter
    jmp pden

;    menu for point mode graphics

pvec:    cpi 06EH
    jz  pn
    cpi 073H
    jz  ps
    cpi 065H
    jz  pe
    cpi 077H
    jz  pw
    cpi 'N'
    jz  pno
    cpi 'S'
    jz pso
    cpi 'E'
    jz  pea
    cpi 'W'
    jz  pwe
    cpi 'C'
    jz  blak
    cpi 'R'
    jz  reve
    cpi '.'
    jz prev
    cpi 069H
    jz  pii
    cpi 074H
    jz  tt
    cpi 070H
    jz  pp
    cpi ';'
    jz  0000H
    cpi 'G'
    jz  gdem
    ret

;    demonstration for gray mode graphics

gdem:    call ghom
gden:    call coop
    lxi h,gvec
    call iter
    jmp gden


;    vector for gray mode graphic demonstration

gvec:    cpi 06EH
    jz  gn
    cpi 073H
    jz  gs
    cpi 065H
    jz  ge
    cpi 077H
    jz gw
    cpi 'N'
    jz  gno
    cpi 'S'
    jz  gso
    cpi 'E'
    jz  gea
    cpi 'W'
    jz  gwe
    cpi 'B'
    jz  whit
    cpi 07FH
    jz blak
    cpi 'C'
    jz  blak
    cpi 072H
    jz  grev
    cpi 068H
    jz  gzeh
    cpi 06BH
    jz  gzmi
    cpi 06CH
    jz  gzpl
    cpi 'R'
    jz reve
    cpi 'H'
    jz  gzeeh
    cpi 'K'
    jz  gzeemi
    cpi 'L'
    jz  gzeepl
    cpi 069H
    jz gii
    cpi 067H
    jz  life
    cpi '.'
    jz  gzeh
    cpi ';'
    jz  0000H
    cpi 'P'
    jz  pdem
    ret

;    i (= line) in gray mode

gii:    call coor
    jmp  glin

;    - - - read routine - - -

read:    in  0EDH
    ani 040H
    jz  read
    in  0EFH
    ani 07FH
    ret
    end