Atari 400 Personal Computer, 800 Personal Computer System System Hardware Manual

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or onlsslons.

that this

Computer

update of the

guarantee

publication

manual

accurately

Division.

the

and disclairns

computer

accuracy

TABLE

OF CONTENTS

II.

III.

I.

INTRODUCTIoN.

DESCRTPTTON

B.
c. SERIAL
D.
E,

HARDWARE

A. PAL.....

B.
c.
D.
E.
F.
G.

11.
I. CONTROLLER

POKEY......,.

INTERRUPT
CONTRoLLERS,,

INTERRUPT
Tv L1NE
GMPIIICS
PLAYERS
AlIDfO.
KEYBOARD
SERIAL

, . .

. .

0F HARDWARE. ...

PORT........,.............,..,...II.25

SYSTEM.....,,..............,,.1r.28

RECTSTERS.

....

CONTRO1,..

CONTRoL.....

CoNTROL. . . . .

AND MISSILES,

....

.. .

and

SPEAKXR. .......

PORT. ..

PORTS,......................III.

......

.. ...,...

.. ..

.. ..

.. ,..

,. .. ...

.....,.,.

...........

. ,. .. ...

... ...

..... .....,.,.

.. .. ..

. . . . . . .

... ,.

.. .. .

. , . . . . . .

.. . ,...

.. ..

.. ..

.. ,. .. ...

. ....

.

.. .I.

..r1.I

',...rr.

.........rr.23

. .......

.. .....rr1.1

,.... .. ,11I.3

......II1.9

... ....I1I.15

.rr.30

.. ,IIt.l

.III.1

. . .III.

,.. .IIL

,.Irr.17

4
12

t9

I

t

rv,

vr,

sAltpLE

HAIDIIARE
A. A'DRESS

B. AI,PHABETICAL

DISPLAY

RECISTER

FlcuRES...,.
A.

MEMoRY

B.

NTSC

c.

APPENDIX

APPENDIX B:

APPENDIX

and PAL

SCIIEMATICS.,.

pRoeRAM...,...................IV.

ORDER.

..

,...

MAp........,.....................vr.

A: USE

WITH

MlXlNG

C: PINOUTS

LISTS.

........,.....v.1

ORDER.

DISPLAY..

OF PLAYER/MISSII,E

BASIC

GRAPIIICS MODES

;.........,...,v,5

....,

,. ... ....

... ,. .,.

. .. ...

...v.

,..vr.

... .VI.2

,........vI.3

GRAPHICS

I

t

t
1

1t

I. INTRODUCTION

\:,-

The ATARI

colrtaln a

6502 nlcroprocessor' 4
R-Alt, and several
Thls nernral ls

(R)

800rM and

MsI chlps

prloarlly

detall to a11ow experlenced

such as

vldeo

ganes.

A11

rnlcroprocessor by nrltlng

to exlst

ln Elcroprocessol

can also be interrogated

reglsters are

!,lany

wrltten. In aone

contalned
gtrobes.

address

.

conventlon

ln 4 separate
No data

on the bus

1s to
reglsters. For
STX
could

(Store

be used

x) or STY

115hed by using

PEEK would be used.

a
equate llst'

uslflg the

addresses

It ls rea1ly

functlons are

I/O
does

help ln learnlng

ceses,
blts are deeded

ls \rhat trtggers

use the STA

exanple, STA

(store

(the

data could

eny of the

When lhe

proglaxmer can refer

the

dtreclly.

not rreceasary

perfolrned by lthtch of

these

ATARI 400rM Personal

I/O chtps, operating

for sddress decodlng

lntended to

descrlbe the 4llo

plograd&exs to create
four Inpul/Ortp\rt
dlrectly lnto

nenory space

by the

wllte only and

nlcroprocessor

cannot be

reading fron the

read only reglster.

ln thls case

the requested

(Store

WSYNC

Y) vould

Accufillator)

perforrns the ltait

ltork

be anythlng).

load instrrcllons

hardltare

to the registers

fot the

functlofls.

chips are

thell reglsters
Just

same addless

lust

register

plograffner to kno{

lhe 4 chlps'

conputer systems

systen ROI'I' expandable

and data bu8 bufferlrg.

chtps tn sufficent

assembly tanguage

controlled by the

$hlch are decoded

as RAM

by leadlng

does. These l/o chtps

slrdlar reglsters'

read after they

glves

wrlte

Sone

slnce lhe

actlon.

only reglsters are

presence of

The usual

hstructlon

for Sync

as weL1.

Readlng

(LDA'

LDX etc').

naEes are

In BASIC'

a reglster

deflned 1n

name ralher

by

$hlch

however

are
value

the

for such

functlon'

a P0KE

ls accoDp-

Ifl BASIC

lt

Prograrns'

the

an

than

nanual should

Thls

(oS)

Systen
Baslc Ref erellce

CHIP T{AME

-

ANTIC

Manual,

I'I4tuaI.
fUNCTION
DMA(Dlrect

NUl

(Non-Maskab

Vertical
I-lght

Vertlcal

WSYNC

CTIA

Prlorlty

be used

a 6502

prograoning narNal,

llenory Access)

and Horlzontal

Posltlon

Pen

l1ne counter

(ltatl

for

control

Color-Lumlnance

all oblects

to

?LAYER-MISSIIE

cre^h{ r a raoi.rarc

Slze

control

l{orlzontal

Col11slon

S{ltches

detectlon

and lriggers

ln conluncllon

lnterlupt)

1e

flne

reglsters

hortzonlal

(display

control

lttcludlng

obJects

(colors

DMA

(4

posltlon control

beBteen

(rnlscellaneous 1/0 functions)

control

sync)

of overlapplag

players and 4

rlth
and the

control

scrolllng

objects

all

the Operatlng

brlghtness

alrd

fron ANTIC)

objects

4343!]!qgl.g9g

oblects)

asslgned

ldsstles)

CII1P

NAI,IE

FI]NCTION

POKEY

PIA

Sectlon
varlous graphics
tlne,
groups

display plogtafi.
the
order
addresses,

nation

describing

(lnterruprs,

system.

and

can be

II descrtbes

Sectlons

alphabetical

the OS shadon

found.

Keyboard
Ser1a1
Pot

scan
Audlo generatlon
Tlners

IRQ

Randon

Controller
Peripheral

(naskable)

IRQ

nodes.
whar

Section

scan and

com.lnicatlons

(digitlzes

(na6kable

{runber

(Joysllck)

control

rhe

Sectlon

each bit

graphlcs,

V conlalns

VI

and VII 11s!

order,

registers

inlerrupt)

generator

conlrol

port

posltion

(4

chanllels)

lacks

and

lnterrupt

lnterrupt

hardware

III

lists

ts used

audio,

Sectlon VII

etc.).

various

the hard\rare

and

(bidtrectlonal)

of 8 tndependelt

control

read ot write

control from

in sone

the hardrrare

for.

includes hex
page

the

fron

lines

deratl,

It 1s organtzea
Section
flgures

ftrnbers

pertpherals

perirherats

lncludlng

resisters

IV contatns
and block

regtsters

and decfidal

i,,here nore

pots)

the

orle a!

by

functional

a sanple

dtagrans

ln adilress

infor_

a

of

r,2

II. DESCRI?TION

I{ARDWARE

OF

ANTIC

TV Dlsplay:
dtsplay at
The PAL
on

NTSC vs PAL. Each frame conslsts of 262 horizor.tal TV lines and each
11ne ls nade
Dlcroprocessor
nachine

AND CTIA

generate

the lelevlsi.on

(US)

systein.

rt-3, The 5502

the rate

(European)

of 228

up

The ANTIC and CTIA chips

of 50

frardes

per

second on the NTSC

systen ls dlfferent and ts descrtbed in the sectlon

color clocks, as sho\rn 1n figure

runs at 1.79 MHz. Thle rate was chosen so that one

cycle ls equlvalenr ln length to tno color clocks. One clock

ls approxlnately eqral ln width to two TV 1lnes,

In any
or rectangles
graphlcs

Bample dlsplay llst

The

(VCoIJNT).

l1nes

The 0

pe!

potnt
Verttcal blank
back to the top
Atarl 800 does not do lnterlaclng, so each frar@

plogran

the

(vSYNc)
(VCoUNT

stAits. AJter vsYNc, there are 16 oore

ttnes of \'BLANK. The dleplay 1lst

descrlbed later) causes the

graphtcs

called

Eode has a

current TV

Ttls reglster

frarne so VCOUNT rufls fron 0 to

occurs near the

(TELANK)

node, the dlsplay is dtvided up lnto soafl sqrares

ptxel8

plxel

glven

la

(plcture

elenenle). The highest resolutlon

slze of I/2 color clock by I Tv llne.

1rl sectlon

IV.

ltne nay be deternined by readlng the vertlcal

of

the screen

glves

the llfle count

end of vertical blank

1s the tlne durlng

1n prepaxatlon for lhe flext frane.

dlvided by 2.

(0

130

to

(see

uhlch the electron beaE returns

ls ldentical unless

which ls belng executed

changes the dlsplay.

occurs durlng the fourth rhrough slxth lines
=

hex 7D through 7I).

thls tel1s lhe TV set

11nes of VBLANK fot a Lotal

walt lnstructlofl

Juop

dlsplay llst

and

graphlcs

to start

'I}:'ete

155 on the PAL syste.0).

flgure VI.5),

verllca1 sync
of vertlcdl blank
where each frane

(to

at lhe end

VBLANK.

A

counter

are 262

The

of 22

be

of

Operatlnq Svsten
Systen
it

(OS)

ln ROM. The 0S affects

!d11 be Eentloned fron tltae to tlltre

(0S):

The ATARI 400/800 cones

sone of the

in lhis nanual. Refer
nanual for nore deta11s. The 0S descrlpttons
verslon

The Os supports

was belng dlslrlbuted when

lhat

nost of the hardnare

PLoT, and DRAWTO coEnands). Tte OS always

the erd of vertlcal blank.
for

televlslon

edges of the

ulth

but

a conpuler

sets \lhlch overacant

plcture

are cut off,

1t ls essential
dlsplayed on the screen. It
ctocks at
that

has excesslve overscan

rtght or left

lhe

This conventlon

is fairly cor0mon
edge of the
rnay

have

thls nanual I'as

graphlcs

dtsplays

Most TV's are

Thls ts flne for

for all lnpotlan!

plcture

!o readjusted

dlaDlav.

II.1

wtth a loK Operatlng

hardware registers, so

in thls

na[ua1 apply to the

written.

loodes

(BASICS,

24 background l1nes

1s used at Atarl to

deslgned so lhat

ordlnary broadcasts'

infornatlon to

for four to elght

overscan.

to

to oblaln a

lo the OS

GRAPHICS'

after

compensate

lhe

be

colot

A TV set

satisfactory

The

0S uses 192 TV llnes
24 ltnes to overscanr
clocks,
nended
or other

The hard\rare

lhat the standards

lnfornatlon

of the prograno.

for its display

It uses

will allo\r

the standard dlsplay irldth

displays of any length,

be followed. The

and devotes the remalnlng

exception night be a border

whlch is nerely decota!1ve

of 160 color

but it ts recon-

and not esse[tla1

to use

.q,q_lleggjglqE:

and cannot
Every

TV frarne durlng

be read the 0S has

its shadow registers,
register.
ii

ATRACT

TV

screen
and the
reads
lhe resulls
code

to unpack the data.

The 0S does

(on

0S reglsrer) is negatlve.

phosphors

sante hlgh-luninance

lhe

Joysticks

1n shadow reglsrers,

lhe 0S changes or
the OS

shadow registers instead
the OS shadoirlng
veclors

I'Ilctoprocessor

provides

lolcroprocessor

(see

l{!:Ig:

OS marlual).

In addirion to a Vertical Blank

to s)'nchronlze to the vertical TV display, this

a Walt

to synchronlze

sync takes effect \rhen

WSYNC, \rhenever

address

sets a larch which

Since nany of

vertical blank
and wriles

attracr color shlfting

h'trlch can occur

and other

reads during inlerrupt

can be disabled by

for Horizontal

the

it deslres horizontal synchronizat

called REAIY. Idhen READY
The lalch is
of the next
resunoe

progran

autonatlcally reset

horizontal blank interval, releasing

execution.

hard\,rare

the

a mnber of

"shadow

the OS takes

thero ou! to the correspondlng

reglsters are

write-only
registers'i in RAM.
lhe values ln sone of

hardware

on all of rhe color registers

This is to

1f the brlghtness 1s

dlsplay is lef! on

for a long tlne. The OS also

conrrollets during vertlcal

so rhat user plograns

Ttere are a few interrupt-related

processing.

of accessing

the

changtng the vertical blank

Interrupt,

prevent

do not have to tnclude

Prograr0s

hard\tare

which

da&age Eo rhe

turned up too hlgh

blank and stores

reglsrers $hlch

usually access

directly. Ho\rever,

and lnterrup!

allons rhe

systed also

Sync

(WSYNC)

cornnand rhat al1ows Ehe

ilself to lhe TV horlzontal line rate. Thts

processor
pul1s

goes

to zeto the Elcroprocessor stops and \raits.

r.rrites to an I/O location ca11ed

Wriling

at the beglnnlng

nicroprocessor

to zero a

(returning

lon.

pln

on the lllctoprocessor

REAIY

true)

the

to thls

to

Obiect DMA

(Direct

chip ls to fetch data fron roenoty

display on the TV screen.
Meoory Access" or Dl4A. It
bus

by sending a stgnal called HALT to lhe microprocessor, causlng the

processor

cycle. The

it r,rishes

to becoEe

ANTIC chlp lhen takes over rhe address blrs and reads any data

fron nenory. Another nan€ fo! Lhis rype of

Once lnitlated,

"TRI-STATE"

this DMA is conpletely and autonatically conlrolled

Antlc chip Fithout need for futher microprocessor lnlervention.

There are l\ro types of Dl4A: Playfleld and Player-Missile

1I.2).

The

playfield

Dl4A control clrcult
snall durnb drlcroprocessor.
fetch its ol'n instructions fron uernory

program

(alpha

screen), and the Iolation of the data

counter(d1splay llst poln!e.). Each instructlon defines the

character or nemory nap), and the resolurlon

group

or rlnes.

Menorv Access): The

(independent

It does thls
reqrests

(open

lrlth

lhe use of

circuit) all durlng the next cornputer

on

halting the main nicroprocessor 1t can

By

(lhe

ln menory L'hich is to be dtsplayed

II.2

primary

of the

functlon of the Antlc

nlcroprocessor)

a lechnlqle called

inenory address

the

DMA

1s

the Antlc

dtsplay

chip resernbles a

list) addressed by 1ts

(slze

of bits

"Dlrect

and

"cyc1e

(see

on the

for
dala

stealing".
by

lhe

Figure

type

Ir ordel to begln

dlsplay

l1st of lnstructloos
tdenory, tell
1lst

potnter)

register).

thls DI,IA the natn

ln nenory,

the ANTIC where the dlspfay

and enable the DMA

control

nlcroprocessor lnrsE

store

data to

ltst ls

be dlsplayed ln

(hltlallze

flags on the ANTIC

sEore a

display

the

(D}.IACTL

In addttlon
chlp
addressea
graphlc8

descrlbed

slDrltaneously

PLAYER-MISSILE

dala on to the

(1f

enabled) occurs

prevlously.

idstructions, and

III addltlon
generates

1n

thls systen.

ed by

where

DMA

programer

the
an exact

addresses for the refresh

Thla ia also coDpletely

count of the conputer

Color-lunlnance

for each
loaded
end lunlnance
the serlal

Player-Mlssile

by the nlcroprocessor

of lts

pss8es

data
color and hrninance
to

the TV dlsplay.

background

detectlon

color

(to

be

to the

playfteld

DlttA descrlbed

colttrols another DMA

gr:aphics

CTIA chip

antoDatlcally,

data stored ln neoory and passes
graphlcs

lnterspersed nith the

This ?LAYER-MISSILE

Is therefore rmlch

to the two rypes

slEpler than the PLAYFIELD Dl,lA.

of dlsplay DMA, the ANTIC

of rhe dynanlc nenory

only

lf he ls concerned with

cycles 1s lrnportant.

I A colot-lumlnance register

and Playfleld

correspondlng

lhrough the

values

In areas of

(CoLBK)

1s displayed.

\'lth

contalned ilr lhese registers,

the screen where there

type. Each color-lun reglster

a code representlng

Player-Misslle or Playfleld
CTIA chlp 11 1s

descrtbed later;.

above, the ANTIC

channel. Thls type of DMA

the

reglsters. Thls

DMA has no dtsplay

type of DMA

playfleld

1lst or

DMA

chlp also

RrlM used

autollattc and need be constder-

real-tlue

ls used on the

progrardolng

CTIA chlp

the deslred color

'rtmpressed"

type. As

\rlrh

before being

are no objects

The CTIA also does

collisron

is

the

seflt
lhe

?rlorltv:

overlap
ttlst
\rhlch

them.
serlal
to the TV

on the TV screen

be made

appear to

Prlorlty ls
data fron

screen.

prlority

The

I'rltlng lnto

thls reglster
sectlon III.

Plavers

whlch

poeltlotl

car be moved qutckly

reglsters.

$ere orlglnally

and bullets.

then. The

four

four playfield

It posslble

!o dlsplay

ltren novlng

as to whlch

pa8s

1n

flont of

asslgned

each object

of objecls

the control

glven

are

1n rhe

and }llsslles:

They are

deslgned

Itowever,

there are

player-rulsslle

color reglsters

9 different

oblects, such

(with

oblect shons

each

other or wlth

1n fronr of the othex.

others are satd

aLl

ro

objecrs by

1s conbtned

can be conlrolLed

reglster PRIOR.

table 1n the ?RIoR

players

The

in the hortzontal

called

to be used

players

games

ln

nany other posstble
color
and

registers, ln
the background
colors ar the

playets

as

and Btsslles,

playfleld)

have

to

rhe CTIA chlp befoie

rrtth

the other oblects

by the mtcroprocessor

The functtons

regtsrer descrlption

and nlssiles are

dlrecrlon by
and Eissiles

for objects

appllcations

conjunclton l'lth

color teglster, raake

sane ttr0e,

a dectslon

Objects

prloriry

ower

and sent

of the bits

snall objecLs

changing

because they

such

as ahplanes

for

the

by

in

in

thelr

the

II.3

obj ec!s

MEMORY },IA?

=

background)

MICRO

PROCESSOR

I'IEMORY

con!!o11ed

Displai

ltst

lnstructlons

(DI,IACTL

Playfleld
Dl,lA Erable

by

)

Ftgure 1I.2

OBJECT

DISPI,AY

SOURC'S

There are a
nisstles n0ay
objects

posltloned

are

([PoS (X)).

sor,

allowlng an
TV 1ine.

The

shape of a player-nlsslle

graphics
reglsters.
address).

processor,
tlme.

rhenever

posltion

ta1

graphlc

the

processor

access
graphics

enable

graphlcs

reglster

The
These
although

The data ln

the horizontal

reglsters

player-ntssile

The

(CRAF

(Dl4A)

ln Demory, I1'rlte

player-Eissile

from rneuory

lotal of four

grouped

be

together and used

horlzontally by

These

reglsrers nay

object to be repllcated

(GMF (X)).

lllsslles

four

have 2

reglsters oay also

they ale usually

each

tegister.

giaphics
sync

couflter equaLs

The same data

are reloaded

graphlc

(X)),

(see

or

figure

arlonattcally
II.3). The

the player-miss1le
(DMACTL,

DI'A

to dlsplay

players

and four nlsslles.

as a 5rh

8 horizonral

be reloaded

nany

is deterElned

Players

have independent

blt regtsters

be reloaded

changed during horlzontal

reglster is

\1111 be displayed

vrith Ire

registers rnay

fron nenory with

prograr0ner

GRACTL).

ls then fully

The

fout

player,

posltlon

at any rlne by

These

regtslers

proces-

rhe

tiioes across a horizontal

by

at afly ttne by

data

lhe

8 blt

(located

tn lts

graphtcs

wlthln

the

bLank

placed

the corresponding

on the display

horlzon-

every line

data.

be reloaded

by the mlclo-

dlrect meDory

lrusr place
base address
The transfer

rhe objecr

(PMBASE),

of object

autornaric.

olre

unless

and

PMBASE

player-nissile

the
oblect is
bytes
Antic,

betrseen

so they

Only

strgle-line
wlth

two-line
1n nenory
tion

neans

DI.{ACTL,

blt

resolutlon

Each byte

are

to be displayed

I indlcates

graphics

The

II.3.
they may
al1
trro
and

The

be only

0's.

pixels

is deternined

speciftes

graphics.

deternined

by addtng

the base

are available

the five nost

resolutlon

resolutior.

1s restllcted

that each

4). 540

and

l28O byres

byte of data

(decinal)

tn rhe player graphics

on

that

the

player's

nay be anyrhtng,

player

graphlcs

a couple

Each byte

for

1n rhe rolssile

each missile.

by the

the nost

slgnificanr

The locatlon

an offset

address

aod the ntsslle

to rhe progranner.

stgnificant

and the

bits oI

slx nost stgnlftcant

This !0eans

!o

certaln

page

ls repealed

bytes

(5x256)

tor

the correspondtng

color-lun
not

may f111

of lines

Just

the
high if
dlsplay

Each ptxel

SIZE registers.

byte
of rhe graphics

to PMBASE

PMBASE are

thar the

boundartes.

for

(5X128)

are requlred

one-tine
area

represenls

llne(s)

ts

to be dtsplayed

rectangles

enttre hetght

the rest of

also represenrs

nay be 1, 2,

(MSB)

dara are

of the address

*256

(decimal).

not used by

used lrirh

blts are useil

location of

Two-llne reso-Lu-

lqlo Ilnes.

resoiur'ion,

elght

of rhe

TV screen.

like the ones

of rhe

the

or 4

of

for

each

The

graphlcs

the

(see

for rwo-ltne

ptxels

whtch

A

in

that

ptxel.

in ftgure

screen or
dlsplay dara ts
etgi.rt plxels,
color clocks,

Plavfleld:

piayfields,

detection.
neloory
menory,

Playfleld

nap

and character.

independent

each

Playfle1d

ldenrtfled

of

ts

generated

ls

Both methods provtde
player-r0issile

the

always

by

its own

generaled

by DMA.

color-1um reglster

by

lwo dlfferen!

generatlon.

llsts

There axe

and colllstott

DMA

technioues:

of insE;ctlons

four

1n

player-Mlsslle
Resolutlon ls

Sase Address

controlled by bit 4 of DI4ACTL,

(PMBASE)

=

),ISB of address.

A.DDRESS
Tvo-l1ne
resolutlon resolutlon

(hex)

+180

+200

+280

f300

+380

+400

OFFSET

One-line

(hex)

+300

+400

+400

+600

+700

+800

PMBASE*100

2I

M

PO

PI

P2

P3

I

I

I

I

(hex)

Mlss lle
Nunber

.21

rP3t

i-T--

rl

tl

tl

| |

lt

tl

ll

TV SCREEN

I

P0l

ii

r42

;i

tl
I

lt

MO

i

P2

I'

M3 I

Horlzonral

ior each objec!
lndependently

horlzontal positlon

regasrers.

rl

­Pl

I

|.'i

MI

Dosirlon

by 8

1s

set

Player-Mtssile
Ver!1ca1

Figure

II.2

Each sectlon
onlo

screen

PLAYER-MISSILE

II.6

Object
only by
of

total height of

vertical posltion

lts Iocatlon

deDory.

I or 2

television lines

of memory

one byre of

DMA

naps dlrectly

TV screen.

is

deternined

In lts

section
oenory
vertlcally,

equals

Unl1ke

playfleld.

for
Playfteld,
1t can fll1

players

on

lhe othet hand, nay requlre

the entire wldth of the screen.

and Elssiles,

Each player

there are oo horlzontal posltlon

can only have one byte of

display

up to 48 bytes

per

per

line

regtsrers

llne.

because

T'here are
clocks), standard
The ddth 1s
nldlh

DMA. The

stored
bytes 1ong. The dlsplay

Dlsplav Llst

a dlsplay progran

DIISTL.

thls counler value ls

!ton,
lncrenent
and so
DIISTII). DLISTI
or when DMA 1s disabled

the resolutlon
to be dlsplayed for a
ca11ed a dlsplay b1ock.

A JUMP INSTRUCTION IS USED.

ls that less R.A.lil ls reql.rlred

0S

g!9If3I-!19!:

rnemory.

fir

The dlsplay 1lst

(or

dlsplay

the

on

&.ltonatlcally irlthout Elcroprocessor control

Each lnstructlon deftnes the

TITE DISPI-AY I-IST CANNOT CROSS A lK BYTE MEMORY BOIINDARY UNLESS

three dlfferent

(160

color clocks), and wide

selected by stortng
graphlcs

Counter that fetches

OS shadow registers

one

Dlsplay l,1st

(s1ze

modes

The dlsplay list is a

These lnstructlons

llst can be considered a dlsplay

counler.

counter can be inirlalized by wrirtng ro

used to address the dlsplay llst, fetch the lnstruc-

(l)

to slxteen

DLISTH should

and

(see

of blts on screen) and the

group

playfield

lnto DMACTL. The advantage of

and fener nachine cycles are

use the standald screen wldth.

lhese lnstluctlors can

(10

bit counter

SDLSTE ard SDLSTL). once

(16)

CounLei, fetch the next dlsplay lnstruction,

be aLtered

DI,IACTL).

type

(I

to 16) of l1nes. Each

lrldths:

sequence

are eithe! one

lines of data on lhe TV

(alpha

narrow

(192

of display

plus

6 bit base reglster.)

only during vertlcal

character or nemory map) and

locatlon of data

(128

color

coLor clocks),

a rarrolrer
stolen for

instructlons

(1)

byte or

progran,

be

thought of as

DLISTIT and

tnltlaltzed

screen,

(see

DLISTI and

group

of lines ts

rhree

and the

blank

ln nerory

(3)

Flxed

(6

btrs) counter

DISPLAY LIST COUNTER

tr.7

(10

DI,ISTI,

blts)

Dlsplav Inslructlon Fornat: Each lnstruction conslsts

opcode only, or of

an

opcode

followed by tiro

(2)

bytes of operadd.

of either an

lopcodel

l6'..d.-l \

-.t

loperand |

------Slngle

)----Trlple

-_-t

lOperand

The opcode ls al{ays

Reelster. This opcode

and wll1 cause t\ro
these
or ln the

opcode of
dlrectly
inslruc!1ons: blank,

Blank

(

next

Dlsplay

t-byte)

I.,

'Iore

(2)

rwo

Dlsplay I-1st

Instructton Reglster

the

by

the

bytes rrill be

current dtsplay 1lst lnstructlon. It cannot be accessed

prograomer.

6lD5lD4

This lnslnrctlon is used to create I to 8 blank
dlsplay

Byte Display Instructlon

EyLe

DIspIdy Instructlon

fetched flrst and placed

deflnes

bytes to be fetched if needed. If fetched,

Counter

ju!0p,

(blackground

the type

placed

(if

(IR)r

There

and dlsplay.

of

lnslructlon

ln

lhe

the instructlon ts

This register is loaded wlth the

axe three bastc lypes oi display lts!

color).

ln the

l4gggTI-.gSeg-9993!CI,

leqlggllgg

(1

o! 3 bytes)

a Jump).

llnes on the

(3-bytes

Dlsplay

(1

or 3 bytes)

D7 I
t5 - D4 0-7 = r-8 blank lines
D3-D0 0

)

D7lD6l Xl Xl 0l 0l 0

Thls lnslructlon is used to
The next two bytes

D7
D6

D5-D4
D3_D0 I

Thls lnstructlon

display block.
D7 I = dlsplay

n6 n=l hvts.i^cfr,r.rlon

D5 I
D4

D3-D0 2-F = dlsplay

-

display llsr

=

blank

speclfy lhe address to

I = dtsplay .I.Lsc

=

junp (creates

0
X = don't care

=

junp

D2IDl IDO

specifles the

I - 3 byLe

uslng address

=

verttcal scroll enable

I - horlzontal

see

"_i' _:t.I

list inEtructlon

Inscrucclon

node

following

InsLrucclon inEerrupt

reload the Dlsplay List Counter.

be loaded

lnscructlon interrupt

one blank ltne on dlsplay)

end of nexl

type of dlsplay

(reload

ln next lwo bytes,

scroll enable

(memory

pages).

character

or

inteErupt

vertlcal blank

Memory scan Counter

for the next

(LsB

LSB ftrst).

-

map

first).

II.8

.rr

x

FH

r&ts]t4 l&ht4 I'r E ts trhErEl

ts.o6<raoatsl

F@6<lq(JAln

Fco6<fq{JA[r]

r@6<14()aFr

N.o6<FqL)crrIr

ro6<i0<JApl

Fco6<rcrJoFt

(co6<F(JAd

Nco6<Fq(j,a

Fco6<laL)FIIr

F@6<rC(JAtst

ts@6<lqc)A14

F@6<rO(,)OEl

tsco6<roooFl

;

ts@6<laOAF.l

6ts@o<FOOtsl

--!

-----1

ttl

| |
II

I

,

Btt 7 of
list
can

The lype of
NMIST, The

lhe user's dlsplay

.olng

tnterrupt

change the

detatls.

a dtsplay

1f btt

colors or
lnterrlpt
current

1lst tnstructlon

7 of NMIEN 1s

graphics

ls derernlned

0S will vecror

1lst

lnterrupt

can

be set to

set. The

durtng

by checklng

through VDSLST

rourine.

dlsplay 11s!

the nlddle

See the OS nanual

create a dlsplay

lnternrpt

of the

NMIST. NMIRES

(Itex

TV dlsptay.

200

and 2Ol)

for proarau-

coile

clears

to

Blts 5
to enable
depends
later).

Meoorv Scan

progtaEner.

(non-Junp)

Thls

directly
rane

a
the
reglster
4K

byte Load Meinory

strlngs

A single

contimratlon

previous

bvte rnenorv

l,lSB

and 4 of

vertlcal

on

the values

1s loaded

It

1Tlstruction.

counter

displayed

to be tndtrectly

byEe lnstructlon

In rremory of data

instructlon.

and

12 of actual counter,

boulldarles.

thlrd byte of 3 byte

hwrc lnorh!.r l^n

a dlsplsy

and horlzoflta1

ln the VSCRoI

Counter! Thls

wlth the value

pohts

(Eemory

Scan

to the locarlon

nap dtsplay)

displayed

Stnce thls

unless the

Counter instrucllon.

type of dtsplay

scro111[g.

and I{SCRO],

counter is not

or ro

(chalacter

does not reload

to be dlsplayed

counter really conslsts

a conttnuous menory

counter ls reposltloned

The amount

in rhe last 2

(address)

llst inshuctlons

of scro1llng

reglsters

dlrecrly

ln mernory

locatlon

the

dlsplay).

thts counter.

frorn that displayed by

LSB Second byte of

byte

(to

be descrtbed

accesslble by

bytes of a 3 byre

of data ro be

of characrei

Thls lnp11es
of 4 btts of

block cannot cross

wlth a 3

lltstrucllon

are used

the

3

tttlttttl

15l 14l 13l r2

Flxed

Menorv
Memory
nap
a shlft reglster
required

Scan Counter) is dlsplayed dtrectly $hen executlng

dlspfay lnstruction.

(4

Map

bY the lnslructlon.

tttl

110

btts)

Dlsplav

so that it can

Instructlons: Data 1n nenory

data is betng displayed

As

3'2t1

Counter ( l2 bits)

(addressed

1t ls also

be

redlsplayed for as nany TV

2

by the

a nenory

stored

1lnes

(btt)

1n

as

1r. l0

Menory
Addresses each byte

Scan Counter

Mernory

one l1ne worth

loaded tnto the

Shlft reglster data 1s dlsplayed for four Tv scan 11nes ln thls exarnple.

In Instructlon Regtster

blts of nemory are

of

the screen.

by 8

(BASIC

OS. Ttese nodes have rectanguLat plxels,
wide as they are hlgh,

ltnes.

TV

GRAPITICS comand). Tvo nodes,

rdenory

of

shlft reglster

used to
Plxel
The 0S and BASIC support nost of these

1s

(IR)

dtsplay nodes 8 through tr', one or two

spectfy lrhal

slzes range froE l/2 clock by I TV llne to 4 cLocks

1s to

C and

be dlsplayed on

E, are not supporled by

lrhlch are approxlmately tlrlce as

grephlcs

each

nodes

plxel

the

In IR Eode F, only one
luElnances
correspoodlng
lunlnance ts deterntned by

In

lR
zero lndlcales background color and
dlfference

In IR modes
of each
l{olrever, only

aB

SHIFT RECISTER

ptxel,

in the

avatlable.

are

plxel

modes
between the varlous modes

four

prevlous

cones fron COLPI'2. If

9,8, and C, two different colors can be displayed. A

8,A,D, and E, two btts are used to speclfy

This al1ows four dlfferent colors ro be dlsplayed.

plxels
Ecdes. The bi!

7

6t5

color

If a blt 1s a zero. then the lunlnance of the

the contents of CoLPFI

can be

413 2tt 0 | 7 6t5 4 2 tt 0

(CoIPI2)

packed

can be dlsplayed. T\ro dlfferent

btt 1s a one, them

the

(abbrevlated

a one hdlcates ?f0 color. T1le

1s ln the slze of the

each byte,

llrto

asslgnnents are

lnstead of elght

shoqrn

belor.

to Pf'l).

plxels.

the

2 blts

one

color

plxel

the

foro

II.

I1

l4eoorv

}lap Dlsplay ltlodes

oS

I

and

l1nst. I

BASICIRes.

odeslHEx

| | I | | I

s

lAl

ltl

lcolors

per

uode

I
|

4

Plxels

per I per
srd.

Line I ritre

|

lBytes
lstd. I

40

l80

160

I

I

Iscen lColor I
lLlnes I

per I per

lPtxel

l0 814

clocks

lPlxel lPlxellPixel

I

ro | 4

I

Blt

I

Btts

I
lper

| 100

lvalueslcotor

tn

I

OI
10

101 l?30
lr0 lPrl

0

I

00

2 I 0l

r0

I

I

Rec.

I
lselect

BAK

|

PFO
PT'I

BAK

?r0

BAK
PTO

?r1

160

I

I

40320

ttttl

0l
10

Prl

I

IGIIM)

rt.

t2

Character Dlsplav

map

dode 1s

character set

bytes of

data depends on
also depending
address
Only the most
descrlptlon
addless
acceptable

to cxeate a character

at hex E000 nay

!g!g

of the character

are assuued to

for the

slgntftcant

ln sectlo[

page

Instructlonst

graphlcs

the hode.

on the oode.

set ls stored

III). The
be zero, so

boundary.

The flrst step 1n

set ln neEory

be used). The

for each character.

The charecter set

The USB

s1x or seven blts

(l,losr

ln CHBASE

other one or two

lhe character set fitst

ushg the character

(or

the bu1lt-tn OS

character set contalns

The neantng of

can contaln 64 or 128

Slgntftcant

(or

of CHBAS are

!yte) of rhe

the OS Shadon CHBAS).

used

blts and the LSB of

start aE an

(see

elgh!
the
characters,

CIIBASE

the

Tte dext

Then the

lgggg

nene selects
froE 0 through
0 through

used

placed

are
reglster
as shol'n

counter v111

na.oe

CIBASE are
byte
glvlng

of

CEBASE,forclng

The

1024

actual dtsplay

or codes. Each

127

to speclfy the

Character nanes

ln a shtf!
rotates,
belon.

After

for lhat
In 20

Eenory

The

aet

bytes for

a full 1lne of

character

used. Th{s

boundary.

a

rotal of 512
40 character per

rrust

step ls to set

1s set up.

nane takes

a character.

(decloal).

63

(declnal).

color or orher

(codes)

reglster.

changing only

lncrenent.

ftne rnrmber.

the

have

128 charactels

the set.

The next

f'er

requlres
The set Inlst

bytes for

character set

up the dtsplay 11st

Thls constsrs of a

one byte. The last

For a 64

The

are

character data

ltne modes

ltne

charactet set,
For a
upper one or rwo blts

aodes

128 characrer ser,

speclal tnfornatlon,

fetched by the neroory

On any

the nane

l1ne agaln

the seven

that
the

the charactet

conratn

use the slx most

to start on

of

8 bytes

glven

portlon

has been

ltne

addresses all

nost slgrlflcant

64 charcters,

each.

for the destred node.

strlflg of chatacter

6 or 7 bits of

the naEe would range

rhe range \rould be

of rhe nane byle are

dependtng on the

scan counter,

of dlsplay

of the character

dlsplayed the

set !o

slgnlficant

a lK byte rnemory

gives

Thls

the shifr

address,

line

characrers

birs

statt upon

8 bytes each,

blts

boundary.

a total of

the

and

by

of

a 512

ltex

I
lCode

Graphlcs

Mode

f4l

chars.

I

L tne

Nunber

of

II.I3

laytes

lNunbe.

I28

lnytes
lln

Char Set

(20

Character

Characrer

Dlsplay

per

llne mode

Internal
codes for

exarnple)

shlft

Resls!er

Codes
Stored ln
Shlft Register

(naines)

Character

Color

Reglster

Select

Data

Addr:ess portlon

Character nane

Address

of

Llne

Char:acter

1n llemory

Set

Addresses

and displays

TV

Color assigned

by color

sefected

data in

reglsEer

on

the

0

I
2
3
4
5
6
7

TV

S can

Lines

r1.14

There

and

7 are supported by

are slx charcter inap modes,

IR rnodes 2

the OS and BASIC

through 7. Modes 2,6

(GRAPHICS

0,f and 2).

.-

In IR dodes 6
one of four playfleld
selected
background
color

playfleld

color ts dtsplayed.

glves

a total of
elght lines htgh and
data byte ls dlsplayed

In IR nodes 4 and 5, each

of elght

(as

ln the olher nodes).

select one of

used

to select lhe character. If the most

the[ data of 10

blts of l0 select PF2.
wlth dlfferert

roodes

lc

This

In IR

makes
standard \ddth 11ne. These nodes are
lur0inances
In IR mode

can be dlsplayed, but only one color 1s available a! a tllle.
3,

and 7, the upper two

colors,

For each

color is dlsplayed.

The four characler colors

flve dlfferent colors.

dode

the

7 characters are slxteen lines htgh

bits of each character Iraoe

3e!g

bit that contains

For each zero data btr,

loode 6 characters

the

plus

a one, tfre

the

the background

for two ltnes).

plxels

i{de lnstead

of data are used

eqEg

nane blt ls

three

(binary)

p1ayf1eld

selects P]I.

Thls

character ls only four

Two btts

per pixel

colors, or background. Seven

signlftcant

If the nane blt 7 1s one, rhen data

nakes

possible

it

to dlsplay l\no chalaclers

colors, uslng the same data but differenr nane bytes.

2 and 3, each

posslble

to have forty etght-pixe1-wtde characters in a

each character ls

plxel

half of a color clock tn width.

is
slnllar

to r0enory loode

l0 Unes high. This nakes lt

F h

posslble to

(each

bits are

that two

deflne loner case characters w_ith descender€. Tlle las! fourlh of the
characte! set
takes the flrs! !!r0
displaylng

(naEe

blts 5 and 6 equal

dala

bytes and noves then to the botron of the characte!,

one) is lowered. The hardware

to

two blank l1nes at the rop of the character

(see

next

page).

selec!

are

to

a zero

\-

In IR oodes 2 and 3. blt 7 of the characler

vldeo or blanklng. This is controlled by CHACTL
blt 2 of

CHACTL

upslde dolrn, reeardless of node, If

character \.rhich has blt 7 of 1ts nane set

vtdeo

(the

luBlnances will be reversed). If CHACTI­each character whlch has blt 7 set w'l1l
dlsplayed). Characters

I and loggltng CEACTI- bit 0. Inverse vldeo and

modes 2

ard 3.

w111 appear as an lnverse

Ilardware collislon

provlded

to

playfleld.
addresses D000 thlough

ls a one then all of the characlers will be dlsplayed

CEACTL

bil I is set, lhen each

l{lll be displayed in inverse

be btanked

can be blinked on and off by settlng

blank

If both inverse vldeo and blank are set then

vldeo

blank character

(solid

Delectlonr 60 bils of colllslon
delect and store overlap
These collislons can be read by the

(hits)

belreen

Dicroprocessol fton

D00I. There are no btts for nisslle to

co11islons.

16 bits for

ulssile to Playfield
16 btts for Player to Playfield
16 blts for }Ilssile
12 bits for Player to

to PlaYer

Player

(P0

io PO allr'ays leads

narne

ls uaed for

(character

co$tro1).

blt 0 is set, then

(on1y

background

nane bil 7 to

apply

only to IR

the character

sqrare).

register are

players, misslles and

nlssile

as zelo,

inverse

If

wil be

e!c.)

The l/2 clock lleDory

node

(IR

codes 0011

be slored in btl 2 of the

nap node

(1R

and 0010) are both

playfietd colltsion registers.

T1.15

code llll) and lhe l/2 clock
playfleld

2 coLltsions and

type

chalacter

w111

Data

Upper Case

IR l,lode

3-Upper and l,ower

Case

Act\ra1
Dlsplay

E

II.I6

Chalacter

Map Displav Modes

os

I
I
lBAsrclRes.

lModeslttEx

I I lchars.lscan lcolor lData lcolor

and

lrnst.loolors I

lper Ista. lper lper

Mode

I

per

lllneslclockslBtrs

lper latts

lLine lchar.l?txel lPlxell

lselect lvalueslcolor

Naroe

Bit

I

rnl 1Il

lDara

I
lRec.

lselect

rrrrttttll

ot2 40l8l:ll

I4

-

7

lB{t

l'o
I
I

7

lBlt

7

lBtt

l=0

I
I

7

lBit

o

|

lr lPrl

0

I

01
l0
1I

00
01

l0
ll

II

I

I

PF2

PFT

?FO
PTI
PF2

PF311

BAK
PFO
PFI
PF2

PF3

| | | | | | |

00
OI

IO

00
0I

10
1l

I

0

I

I
I

!
o

I

L

BAK
PFO
PT'I
PF2
PF3

BAK

Pr'0

?FI

PE2
Pr'3

rr.17

Vertlcal and
to Eove srnoothly.
of nenory.
of

the screen rfils!
6oved easlly
Ilorever,

llowever,

ln a

thls

results

to another, not

(VSCRoL
or vertlcal
character

done by

the nenory

another

and HSCROI,)

notlon,

helgh! vertlcally.

lrrcreaslng

scan counter

characrer

llorlzontal

Me.oory

thls 1s

be noved

jerky

Flne Scrolllna:

playfield

nap

extreEely

snoothly. Character playfleld

fashlon by

1n a large

a smooth Dotlon.

and counters

up to one

character wldth horlzonrally
After this ouch

the value in

ts nodlfled

distance,

?layfleld

can be rnoved

tlne-consunlng

chaoglng the nenory

posltlon

For

provtded

are

junp

fro.n

thls teason hardnare

ro a1low snooth horlzonlal
snooth xnotion has

these reglsters,

and sDooth .0otlon

objects are dlfflcult

by rewrttlog

secrlons

if large secrlons

oblects

can be

scan counter.

one character

posttion

reglsters
and

up to

one

been

nenory 1s reErltten or

1s resuned for

Vertlcal
upward by
dtsplay

blocks at

varlable

zone trlist
ehortened

verElcal

ScrolllnA:

uslng VSCRoL

the upper and lower
slze. In

be shortened

fron

the botton

A zone of

and bir 5 of

froid the top, and

(t.e.

be dlsplayed).

The vertlcal
counter
vertlcal
standard
for

wlthtn

scro1l1ng,

va1ue,

upper and

character

If btt 5 of the
display

blocks, then
If blt 5 of
display

blocks, the second block
r'llf coun!
shortens

that

dlsplays, it 1s

the

up until delta=VSCROL, lnstesd of

dinenston

the ANTIC, called

lt starts

detelnlned by

lolrer case text

7 or 15,)

lnstructlon renalns
lhe second block 1s displayed

lnstructlon goes

dtsplay

block fron the botton.

To deftne a vertlcally
sel blt
consecutlve blocks but
reFrlttren
conslan!
the standard

5 to I ln the first dtsplay instnrctlon

the lasr one. If rhe VSCROL regisrer is no!

on the f1y, thls results ln a rotal

IujDber of 11nes

(provtded

lndlvidual block stze). If N
rop block will be N-VSCROL
VSCROL +

I 11nes:

followtng page

1s an exanple of a scrolled zone, top block, for 8 VSCROI-

(N-VSCROL) + (VSCROL

valuesforN=8.

playfleld

on the screen can be

rhe dtsplay llst lnslructlon,

boundarles of rhe

particular,

the flrst dlsplay

the last dtsplay block

not

all of the top and botton

of each dtsplay block 1s

the

'De1ta

Counter'
at 0 on the firsr line, and counts
the current dlsplay lnsrruction.

display, the end value is

zo[e Eu6t have a

block rrithln

ftrst be

blocks dll

controlled by a 4 btt

(DCTR),

Wlrhour

up to a

(Ex:

Ior 5

9.

unchanged between consecutlve

1n the normal fashlon.

fror0 I

to 0 between two consecutlve

\'111 start tu{th Delta = 0, as usual, but

lhe standard

value.

scrolled zone, the most dlrect melhod ls

for that zone, and 1n all

scrolled

zone that has a

that the VSCROT value does not exceed

standard block size,

and the lasr block wtll be

),

=

111.

Shown on the

l1nes

(N

>

VSCROI

1s lhe

+ 1)

scrolled

The

lhat

color

Ihls

to

che

Horlzonlal scrolllns is descrlbed

II.

under

T8

HSCROL ln sectton IIt,

o

I

2

T1

2

li

5

1

-l

I

2

I

2

5

-t

I

z

-2

I

z

l

5
7

I

fz

I13

I

3

t:

5

7

7

z

5

5

5

7

2

3

T

5

7

J

I

l

2

z

5

3

5
T

I

I

2
3

z

3

5

7

I

2
3

5

F

'7

I

2
J

5

7

I

2

J
4
5

7

-,

S+np19

. _ .

whlch

slandard

R-Al1

nlth
nachtne,
are

hex 70's
4 teUs
address
te1ls
next
code

The

960

The
atattlng

MSB

scan
nodes
10

23

for
address
bytes
oS lErst

of

Thls
counter

on

the

Dlsplav

dlsplays

screen
room
the

the hardware

(7C40).

the hardware

bytes

Junplng

are

address

the

ls a

dtfferent

example

40 characters

ntdth.

for
dlsplay
!o create

Thts

specify

and walttng

to

Junp

the

set

up the

of

address

slEple

1s only

tn

Llst

.The

the

character

l1st
to

ls

to

dlsplay
23

to ts

11st

of characlers
dlsplay

the

of

rhe

exardple

loaded

ltnes,

Sectlon

Exanpte:

OS sets

would

24

blank

reload

rhe

nore

7C20,

dlsplay

character

at one
change
IV.

BASIC

across

the

aildress

one

ltnes

until

1lsr pornter

because

by 24

up the allsplay

nanes
start
1i[e6.

Bernory

of

line

of rooile

the

rhe

start

to

11st

ser

point.

chiracrer

starls

ro\rs,

at the
at hex

The next
ih. d.t.

of IR
end

be dlsplayed,

(7C20).

(EO).

orlly

top
7CiO.

scan

noale 2

2

of the

of the

(oirsiu

It

one

It

ls

eets

out

in os

Thls
of UU.
byte

cou;ter

to

characters.

alisplay

also

node

posslble
and

1s IR

lts!

The

1s

wlth
be dlsptayed.
characters.

nex!

verllcat

40 bytes per

;nd DLISTL)

sets CIBASE

ls used

colors,

graphlcs

node

near

flext

the

On

a
three

a hex

the follor,lng

Eex

llst.

and

to have

etc.,

node

2

nlth a

top

of

32 K_byte

bytes

42,

The

The 2

The

4t

is rhe
btank,
The

flext

l1ne.

to the

to the

the roenory

different

as shor,rn

O

II.19

Mode 0 Dtsplav Ltst

0S

(40

chars x 24 1lnes)

Ad.i raee ahav\

7C20

7C40

Data

70'\
70

70)

42)
40

7C)

i)

;l

'.(

2l

i)

-)

4l

20

1C)

l

)

(hex)

24 blatrk

1

reload

roode 2

IR

I

t

23 nore IR

Junp back to 7C20

walt for end

1

960 bytes

(character

l1nes

meroory

mode 2 tnstructions

of dtsplay data

naoes)

acan counter r.Ith 7C40,

and

of vertlcal b1ank.

cvcle countlns: As explatned

cessor runs at a rate of 114 machine cycles

ate 262 Ilnes
(The

PAL

Each nachlne cycle
are 228 color clocks on a TV 1lne. The
have a

40
screen 1!

(WSYNC)

uachlne cycles betore the beglnnlng of the

thus change
the next 1ine,

xefresh
ls that each byte fetched
dlsplay Ilst BeEory nap inslruction

ls

every l1ne,

refresh

and one cycle every'other 11ne ln the tlro 1lne

DMA can be enabled rlthou!

enabled lhen olsslle DMA n111 also be done
Player DMA iequlres 4 cycles every one or tlro
resolution

ptxel

nachlne cycles. Thls 1s !,'hen the bean returns to the left edge of the

lnstructlon stops the 6502. The

The ANTIC chlp steaLs cycles fron the 6502 tr order to

and fetch

only

conllnuea

l,rsstle Dl4A takes one cycle

per

TV frane and 60 frames

(Europeor)

slze of Il2 color clock by I TV Une. Ilorlzontal blank takes

preparatlon

graphlcs

fetched

unless

used.

systen ls dtfferent. See

ls

equlvalert

for dtsplaytng the next TV 1lne. A walt for Sync

or colors durlng horlzontal blallk lfl

graphtcs

on

the

pre-enpted

durtng vertlcal b1ank.

data ehen needed. The

fron nernory re$lres one Dachine cyc1e. If a

flrst 1lne. MeEory refresh takes 9 cycles

dolng

prevtously,

per

1n length to 2 color clocks. There

highest resolutlon

processor

extends over several llnes then the

by a htgh-resolutlon

per

l1ne ln the one-1lne

playex

DMA. l{owever, lf

the ATARI 800

per

second

the sectlon on

next

resolution node. l,Ilsslle

(see

llnes, dependlng on the

Tv ltne

on

the NTSC

ts restarled exactly 7
11ne.

Tv

general

graphlcs mode. Menory

Dl4AcTL, GMCTL blls).

5502 ndcropro-

(1.79

MHZ). There

(tls)

NTSC

graphtcs

prograo

lhe
preparatlon for

do memory

rule to

resolutlon Bode
player

Bysren.

vs. ?AL.)

nodes

can

r:emenber

data

out of

DMA ts

II.20

Each

fetch of

are required

for

a dtsplay

a three

ltst byte

byte tnstructlon.

takes one

cycle, so

three cycles

Player/mlsslle

during horlzontal

the

first l1ne

In nemory

nap modes,

of the display

use ln succeedlng

fetched
graphics

dala iB

the
fetch the
refresh
screen

tn

the hlgh resolutlon

occurs

durlng

the first

data needed

fetched,

In

lhe 40 x 24

cycles durlng

character codes

cycle

wldth

lnstead of

so two Denory

The menory

every four

refresh

A11 lntelrupts
Wlth
horlzontal

depends
scrolling 1s

standard o!

b1ank.

The time

on

at which ANIIC

the

enabled.

graphics

see I{SCRoL.

and display

b1ank, tf

they are

the

l1nes,

In

ltne of

for that

slnce ANTIC

character rdode,

the

top ltne of

and

the usual

refresh

ls done

rnodes.

cyclea

reach

narrow

unless

the 6502

screen lrldths,

node,

Horizontal

list

lnstructton fetch
required for

graphlcs

dara

hst instruc!1on,

character

each ron

llne.

renembers

nodes, the character

of characters,

Or the next ltnes,

the character

&{th

a standard

each row of

data, so rhere ls

[1ne. ]-ess DltA
cycles I'ould

fast enough

Once rnenory

pre-enpted

refresh

by Dl4A,

near rhe end

refresh DMA

does cycle

screen

stealing

{1dth and

scrolling

take
llne.

place

the next

ls fetched

lhen saved

DMA

as needed rhroughout

by ANTIC

codes

along rrtth

only ihe

codes.

screen wtdth. nost

chalacrers

only rlne
occur in

!o nake

ts requlred

up

slarts or

ale requrleal

for one oenory

wlth a narro,

thls case.

for

the lost cycLes

a 1lne, lt

of horizontal btank.

starts after

the end of

ls deterndnlstlc,

nhether or not horlzontal

reqrtres extra

graphtcs

for

are

the

graphlcs

of

to

but

data:

ANTIC
delaylng
clocks
inlernal

does horlzontal

the

tlne at which

(which

lnvolves half

delay.

Theoretlcally,
or

colors

I'lth

all
ard ls

There
These

which adds

rron

the DMA

beyond

are a mlnber of

occur in

in

the flyi, t.e.

going

the scope of

the ANTIC

lhe color infornatlon.

the fly is dlfferenr

scrolllng

1t DMA'S the

of a nachtne

it

possible

ls
on, rhe cycle

thls roanual.

delays assoclated

and the

fron

that for changtng graphlcs

of an

data. To do

cycle), ANTIC

to write a program

during

the nlddle

counting

CTIA, The

Thus

II.2I

even rllnber of

color clocks

an odd nunber

has a one

vhlch changes

of a TV llne.

gets

with

to be

the display of

qulte

ANTIC sends data to

the rlnlng

for changing

on the f1y.

by

of color

color clock

graphlcs

Iiowever,

conpltcateal,

graphtcs.

the CITA

colors

on

Itortzontal

When DMA ts enabled, cycles are slolen at the tiEes shown belol'.

End of

Lprevrous+l
ll,lne | |

I,ISYNC

Blank

Horlzontal BIank_____J

20 nachtne cycles

DUA

Tlntne

(40

-_

. ^t -

r-v rerresn cycres.
char, and
dara DMA

orr.hl. m-,{ c )

Interrupt
Address

Player
Dlsplay 1ls t
Mlsslle Dl,{A

color clocks)

graphlcs

(depends

(3-byte

DMA

lnstrucrion)
lnstruction

on

dlsplay

fetch DMA

llst

Cycle Countlnq Exanple:
dlsplay l1st
dlsplay list DI,IA takes 32 nachlne cycles. It takes 960 cycles to Dl'lA rhe
characters and 8*960 to DMA

cycles for each of 262 1ines, except for the 24 tines wnere the characters

are read, where only I refresh cycle occurs.

Thus tbe total DMA
1s 262 llr\8 with 114 machlne cycles
cycles
node 0.

(Untted

The PAL systeu has been destgned so that mosl
belng modlfled.
hardtrare

system

per

NTSC vs. ?Al, Svstens: There axe tr^ro verslons

lt Is runnins on

given

DMA descrlptlon

dtsptay llst

chalac!ers
character data
refresh

!ota1

fraDe. Thus 362 of each

States T,V. slandard)

Ilowever, sone dlfferences nay be notlceable.

reglscer

page

on

(PAL)

per

vhich a

and adjult;ccordlngly.

fhis exar0ple

II.24. This dlsplay lisr 1s 32 byres long so

characrer da!a. The refresh DMA

the

uses the 40 char:acter

Machine cvcles

40x24 = 960
950x8

262xe-24x8

=7680
=!!!!

1083 8

frane ls

and

progran

10838 nachine cycles. one fraroe

per

ltne for a total of 29868 nachtne

frarne is required for DMA tn 0S

of the ATARI 800: the NTSC

(one

PAI-

of

the European T.V. standards).
programs

can read

deternlne

to

wlll lun

by

24 l1ne

takes 9

32

graphlcs

wlthout
There 1s a
which type of

..__

-

The PAL T.V.

gaues
1lnes

fot thts
llsts
be
nodlflcetlon.

lflll be slot'er

per

by adding

do not have

shorter.

frax0e

PAL ATARI

has

a slo\rer frame

irnless

(312

lnstead of

extra 11nes

to be altered.

800 colors

rate

an adlustneflt

262r.

at

the beglnnlng
llor,rever,
are simtlar

(50

Hz.

instead of

is oade.

T\e Arart 800 harilr,rare

thelr

to NTSC because

pAL

has roore

of vertlcal blank.

actual vertlcal

60 t{2.)

cordpensates

of a hardware

so

T.V.

Display

heisht

\1111

B.

frequency,
frequency
port
\rhlch

ously
can
and
blts
resolutlon,
channels

and
reduced

MEZ.

audlo chamels
Thus eech
clocked at lts
by blts
senpled
change faster
the dlvlders
the low freqrency

POIGY

Audlol

block dlagran.)

selects

Irequetcy

fron 54
alternately
4 can alternately

4 and 3). Thls

Poly

4 blt)

Thel!

by the

Ttere are

nolse,

dlvider,

the tlolse

Dlvlders:

KHZ or 15

2 chanrels

of 8 blt.

Nolse Cou[ters:

used !o

to 9 bils

outputs,

at

channel

olrn frequency.

5,6 and

'rdlvtde

than

are therefore

4 seni-tndependent

arld volune

controlled

Each

KHZ.

be clocked

be

a11on6

of 16

generate

(AUDCTL

however,
a rate detelnlned
appears ro

7 of each

by

the saopllng

noise

to

control.

channel also

(poly

A11

from

clocked \di!h

rhe followlng

btt resolutlon,

There

random

blr

contatn

A1IDCX regtster.
N[ frequeocy

acting
pass.

audlo channels,

Each has an 8

by an
counler)

4 frequency dlvlders

(AUDCTL

7), These counlers
can be sampled

Thls poly

8 blt regtster

has an 8 btt

conrent, and

btt O).

1.79 MHZ

ale

nolse. The

by

!ate. IIr

asirlow pass,'filrer

(AUDCTL

the output of

oprlons:

or I

polynoEial

3

tndependently

each channel,s

separate

dtvldet,

poly

counter noise

Because

these nodes

Ire$ency

17 btt

lhe output obvlously

each lrith its

"dlvtde

b1t

(AUDFX).

conrrol regtster

the volune.

can

be clocked

dividers

bits

6 and 5).

dividers

4 channels

channel of

counters

poly

are ;11

counters
the

clocked by 1.79

frequency dlvlder.

saopllng is controlled

poly

(poly

clocks,

by Ni,

(See

andlo-serlal

(AUDCX)

slmrltane-

I and

Dlvlders 2

I and

of 8 bits

16 btt and 2

(17

b1t, 5 btt

counter can be
by the

(3

types)
counters are
noise outputted)

allo\rlng

3

four

cannot

(AUDCTL

o\rn

3

only

The output

pure
frequency
can be routed

tones

set by

of the

(sqrare

through

rrave

the

ridtvide

a high pass

notse control

type),

by Nri countet

polynonlal

or

ftller

circult

rr.23

descrtbed above
counter noise

(1o\r

pass

1f desired

at a rnaxlurE

clock).

(ALIDCTL

conststs

This output

blts 1 and

of

Audio Nolse tr1lters:

trreqrelrcy

Notse

Frequency

Any chanflel nolse output

voL

chennel

-byN

channel

(or3&

-bvN

,)

Chendef I output

;\

,J

(vtthout

(wLth

fctaonet

lL-

I

v

high

htgh

o' "

pass

pass

t

f11ter)

fllter)

f!equency

Chamel 2 output

(!?-lth

Clock

blgh

pass

Freqtrency

filter)

"D'r

a

tha[ the clock ra!e,

the two

nolse whose

channels

by the

the

to

hlgh

ftlter,

Thls

pass

filter conststs of

"Aigh

excluslve-oR

foUow

pas8

filter

Pass" c1ock. The input and output

lf
the

(ll

or 00)

pass

fllter,

clock

hlgh

The

1s lncluded ooly if bit I or 2 of

Gate. If the fllp flop lnput

lt

loput and

pass

Lower

is

gtvtng
rate. Only

pass

clock for channel 2

very 11!t1e drtput.

passhg

clock fo! chatlnel I

Elah Pass Fllters: The htgh
attd an elcluslve-OR Gate. Ihe noise control clrcult outpu! ls
thls fltp flop dt a rate set
of the lllp Flop
ls changing mrch
through the excluslve-OR Gate. l{owever,
the f11p flop outpul w111 tend
Gate lnputs lll1l nostly be tdenttcal
Thls
olnftolid

AIIDCTL ls true.

glves

I

and 2 have such a htgh
cones
froo the channel 4 dlvider.

fro.n the chanfle] 3 dlvlder. The hlgh

the effect of a

frequency 1s set by the htgh

pass
faster than the clock rate, the stgnal !1111

through

crude

pass

fllp flop

sanpled

pas8

easlly

excluslve-oR

by

cones

J9Jtg9_994!gf:

each chennel. Thls ts a

allons selectlon of one of 16
true audlo lnFrt. A loglc zero
glves
codtrolled by bits 0 thru 3 of AUDCX.
lnvoked by forcing thls
thla
nected fron

AUDCX) determlne

zero to the volude control blts of AUDCX. A11 ones slves

an open clrcult

mode

The ardlo output of any chennel can be conpletely turned off by

dlvldels,

the

lhe chaIlnel outpu!. Olrly the volune control blts

A volune control clrcult ls

crude 4 blt dlgltal to analog coDverter that

possible

audlo ltlput !o thls volune clrcul! al\rays

(zero

the channel output current.

current) outputt The volulle selecllon 16

clrcult's arrdlo
nolse counters, aod fllter clrcults are all dlscoo-

oltput current 1evels

"voluxoe

input

placed

control on1y" node can be

l.lth

true

at the output of

for a loglc

blt 4

of ALTDCX. In

(0

to 8 of

rnaxfid]n volur0e.

wrltlng

c. SERIA]- PORT

The serlal

1lne, a ser1a1 data lnput

bl-directlonal serlal data

descrlbed ln the operatlng Systen Manual. Data ls transDltted and recelved
as 8 btts of serlal data

by a logtc true

(blt)

oulput

ra!e, not 16

clock

port

stop

goea

coflslsts of a serlal data output

(recetver)

clock 1lne, arld

preceded

btt.

tines baud rate. Transnltted data changes

true. Recelved data ls sanpled rhen the

Irput and

1tne, a serial output clock 1lne, a

other rolscellaneous control lines

by a logic zero

outpu!

clocks are

(transolsslon)

start

bit, and succeeded

g$g! to lhe baud

lnpu!

qrhe[

clock

the

goes

Sg4e1_9.g!!g9:

\alrltes 8 blts of
audto and sertal
nisston 1s flnlshed

(SERoUT)

an empty
data), and auto!0attcally serlally
start-stop b1!s attached. If the

reloads SERoUT before the shlft reglster 1s conpletely transnltted, the
serlal

to the oltput shlft reglster, lnterrupt the

(SERoUT)

transnlssion

Ttre transElsslon sequence beglns lrtlen the
peralle1
port

block diagran). vhen any

the

reglster

w111

dara into rhe serial output register

previous

hardware a'111 artonatically

(ready

be soooth and contlnuous.

to be reloaded wtlh the
transnl!
processor

lhe shlft reglster contenls

responds to lhe interrupt,

transfer

processor

r1.25

processor

(sERoUT) (see

data byte trens-

new data from

lndicate

to

next byte of

ltrlth
and