ÿðáãëþ› CORRECTING GTIA-MODES & VIDEO OUTPUT› $=› (By Jiri Bernasek - BEWESOFT)››  After many years of using an 800XL, I decided to buy a second Atari 8-bit compu~M(for a kind~Nsoftware-testing). I got the last version~N00XE, but unfortunately,~1display~¡on TV wasn't fully OK. There w~two problems~?at I already came across at some~	Ä-mee~¬s~ˆnow I had a chance~D
examine it a ~Ddeeper. Fina~ŽI've foun~8way~5correct both~Ñ~ . If you~4~s~Ÿ~ - keep ~ºing~F~ó documentat~DBis~Ãing!~DÜT~%irst~H~ bad~ME~D¡ called "~„Q modes" (GRAPHICS 9, 10, and 11 in Basic)~GRoccurs~cably~D—all~¢s~GàXE's made~<China~G¦'s~D:ug insid~ø~ƒchip, mix~£bright dots or~„.tical lines into 16-sh~agraphics (mostly new demos~„w~Ea do~„1k~DÕhow~r~Š½~G~¿~E, just type (~þ~D9course):››10 ~J.:FOR X=0 TO 15:COL~:PLOT X,0:DRAWTO X,64:NEXT X›20 GOTO 20›RUN~D¼You'll see~Änquare, black~„­~Å;eft ~D7, grey~D\~middle~F®white~0~EF~E~~FUness~„~áincrea~Åüfrom~ato~9 (step-by-~~Eüen~O<is OK~z~Dhneed~Dj~Cead~†´ollow~cpart~DEthis text. But w~Wt~ÅÃa~ÄÇ~Â~Oó~HÜ~ò~¨~
Oe~G/~¤~…V~†þ~…| bes~Äôlu~Æ8~J~Ä=ase would b~Åäreplace~Ewith~ÉÆon~D–u~Dai~EI~šmpossible (unl~Df~Dhave ano~à broken XL/XE under table).~È¼upgr~„Õdescribe~•low will help~ou~ù~ª~DZ~§-~q~„B~D† only five cheap~Å`s (avail~t~„$every electronics' sho~Dë~DÑa few~$n~C~®hings like some wires etc~Fc~ÇK~“~²NOT~DV100% perf~DA(still)~HE~Ärst awful ef~#s~Happear, so~ˆÎfir~DÁ~…›~Eôcreen~ibe OK~„~I;~IMoes~IÀ~Ï
of pixels (~ÊÏ~ÿ10~¤no~6color~'10~(1) - that's~,so simple.›  I~†±~† hand, it a~è~PMG graphics a little - on mov~DKobj~.(ove~‡“modes)~Æ6's al~EE~„g~1strang~‡¨s~…c PM~	Hmay look a bit "flat" (~E-pair~Dânked toge~d). W~É¦~p fine high density~ÅÑ~È ~Ô(it h~DÆn~
 ~„q~–~D·i~D4~È8)~Em~Eàbe unread~¼~I_why~`~HÚallow~Æito install a~…@~9switch. G~H`~E8~GŽthan~Iì are~E¾~F›ed~Æ“o make~texpansion~orself,~Íq~Æ/components from an~Ò`~Ç_l~„)~ÄE~ELtools, a good solder~DÌiron~~Dªof~†erienc~Ä|th precise~e work~dquite~
=pat~;. So, if~À~ø~
Yd~Z~Åc~‡~S~álicated Prin~Circuit Boards, better as~„cf~Vd for help~Æ¥author~”this~‡<~Æ?respon~…~5any damage caused by in~ÈÐ~Gõat~Dš~P~‰, or improp~Ç}l~ÅOf~Fm~	Ï~F°!~Dñ~Dwhat~LÚ:  74HCT00,~
74~	
5~
86~
138,  Resistor~„\kOhm,  Capaci~0 nF,  a sm~„³~†© (op~Èal),  piece~®an universal b~Dd (70x28mm~(1-2 metr~„Ùf~Dul~Ežthin wire~h~„q~†¡enti~
/non-~3ck~4 (diame~EÇbout 1-1.5 mm)~ÅI~…< can't get~Ew~þ... chips~Å may~†êus~ÆGclassic 74LS~,(These~3 only "eat" more current,~:func~Eæ~„1~„ame. A~]74A~N~ÄÆpos~…>~Æeven~š~might~Ç bu~¶at'~†wsure. Old 74~Jn~
~Utypes~…s~ÇRtoo much~¡.) B~O~K~‹robably~best~Çû~Çt~ä~Äynsiv~Dan~*others (around here)~Å8re~< special requirem~„Â~Gª~Br~ˆ~~…ä~‰x- almost~ÅU~…z-size~Ë should be OK.› ~Å®~†t~
a kind~„?laboratory-~D&: with holes in~„ßqu~²ras~„Kof 2.5x2.5mm, each~1an~‹¸solder~Äªpoint ~F. Y~Ê“ a~Ê28x11~+s. (I~DÑ~…r~ˆ to mak~†upgrade~w~D-~Ä_~à~ˆis w~é~Eä~E¦difficul~GÂs~expansions~E–~ueasier~sdamage)~HD~Ñâ~MP~EŒ~…i (one way ON-OFF~„îenough), suita~Ófor montage into back panel~Ó~Åiomputer~Å°~‚first step~Tprepa~Ef~0~H~Gwhich~)shown at figure 1. C~‡funiversal~‡"to correct ~„W~F+inser~0~Šg, a~Z(~~Äÿ,~‰·,~Š´~Ethree~Fôs~±~Š.thin wi~Å"S~…:~klead~*~…e~	y (a~‹~Åc side)~bc~…~Gnn~isary~ÄÃtrud~D)~fs~Åˆn,~†R~Eµ~DÝ~Êco~8~Dßs on~‡È~d~…½ may us~Dï~	µ (non-~	Î,~5~Øo~Z~EY)~†œi~•Ûlink~+~Æ only~ÆV~š~P. Leav~Ænumb~b~0f~DZ- y~Æ^~µthem ~“r. All~û~E(~F9metal parts~„±~OÞ~FX must~„ßhidden un~Jv~†¨~D÷ co~„E. A~Fšend~G^~two "legs"~…ôfix~DŠ~I in its place. T~E•b~ÄÙa centimetre~†ãick~È, be~„˜t~D>right angl~‡¯p~Ei o~ÄU~JA~Ò~È*~Ç"s~!a~+e half~Eàb~2ed~Da few~~»~I¦~G~†ße second~J~Å ~‰x~Ñ5mm~
v~çhen check twice,~‰every~„[g~AOK~ÅúNot~DJ~‡÷74HCT...~Æq are electrostatic sensitive device~Æªwell~~É«~Ä~Dyour~Eùu~…+~„æshould~I~…Ža goo~~¤ron - NOT~F imp~„Òransformator-based~‹ (~‰×tip~DŽb~ÄÓ~JÚ). I~Ä$bes~EÝ~Ç‘~2grou~Dß~D~;a~‡A~„øre work~•~„Ìoge~…å~n~°~D®~õh~
~Ù~†V~Dívoid an~OUdischarg~Ähor at lea~£uc~Ð~ž~ç~a~~‚)~Fç ~„Û~½go~Å~ñtinu~Æ;~Ó after a pause. Don't wear cl~ÄËs~Ertifical m~Äóial~D÷nd d~/move too m~¯~D PVC floor~Ä~Eroom~…š~‡!m~ÅYbe also damaged by heat -~Ä>bet~~e~‡0~Äå~klo~Ò~ä~D’~„am~[ (w~„ÿ~…‹ase become hot,~Š~‰€top~„f~E%ll ignor~Ese ad~‡Ý~ŠÒ~Ç¾~ª(i~„Jpossib~„—~ÄB~J~Ääuccessfull 99~©s, but still~Wre'~Æ1dang~Å
at 100~„Â~H¼ll destroy a friend's~ÉP)~ÇÁw, ope~GhXE. Re~E“4 screws~„Q~ibottom, lif~top cover~FÎcare~²y r~A~$key~Å	. (~Ë¾~„²~Ç=it from a~ÈOor -~D~O!~Dõse~„Óds~D®flex~E4plas~„ÿare easy~„¢~F_~F+almost im~Jfo repair.)~ø~¨an~„«r 7~	ñ~Æ/~Àedge~„Ä~Å~è~E ~·~J~F. O~DL~metal~H!bend~ÅFhe 7 fixations~“~Dðtra~„Ñ.›  Look~Dsfigure 2~ut~Ä”o fi~˜ne~„!ary~ÆÕ~E~XE-~HpHop~Git~„match~%picture.) Cut~K¸~Å	hown 3 ways besid~FÉ4050~Æ!clos~ELGTIA (on~E!~†ù~6i~	Ž~FX~D!). C~”!lo~N~F,pi~Ö away~L^~Ï~†ª p~DÀre 18~©rt~3of insulated wire~F6~Çöthem~±~E9umbered~H81-18~¯upgrad~s~„y length~`~Vs~ˆÁb~Ääap~n~X~‡¾ion with~K—~H“, a~@wn~…Ç~Gß. (It's all~Gstt~³o ha~G#~	zrt.) If~Äª want~&install a~ÄUable-switch,~ý~ˆÞ~F~­~ 19 - this~~
Ûlong enough~Æ4a~‡9fu~„8 posi~ê~Fø ~r (somewhere ab~Hàmoni~ÄÔ~ÉÞ)~DÌF~ˆÈ~G'"+"~E±"-"~J&(~is~;~FlANTIC pin 21~Få~4to~1 -~HAcheck it)~Í@put~Mêin~DCts place. Be~˜"legs" a little, until~Ä÷perfectly~ËQ~Fk~Äà~ØŽC~~he~Äê~Ez~	gmus~DÍu~Ocorrespond~
S, b~¼~Z (~top~DŒ~	‡) may not~DÎmo~Dùhan 1mm~Kš~FJ(tha~„€~ÅŒarge~Æåbelow)~Æ~
Þon~~~g~
¸~R'~EMstic cover~¹~âbe far~ˆZ~Åâ~D|leads~kn~Ë²~Hto~KG(Good quality~ó~„)requi~ÄÜ~„„, becaus~í~wo~Hžwill hol~Fëwhol~PVin~‹)›  Now~ˆˆ~Ä«~Ë˜~ÇS~T´~,~ŠÜon fig~ÄM2~Fe~Åt~Åˆ(19) fo~F~Ç[~²b~f~Èlat~D\now b~„µit away~FV~:~F2›› ~‡|everyth~žtwice,~&n~
Õ~Éª(TV)~Å4power supply (don't~	/key~F*- i~„?eas~Åadamage~Îutur~Fcompu~Ä(~<) on. It~Duld work~9you'll see "READY". If~Fcre~„(tay black~E+a~E@~„9im~‡ínormally -~HEoff~_search~9mistake~Ä_a~ŠY~‰V, ~]short circuit.›  W~D;~Ó~½s,~ó~JVdisk drive~|insert an auto-start~D”(boot)~/with a titl~	ñin a 16-sh~„¦mode (GRAPHICS 9)~©bet~‹HIP (contains both ~
*~†10~ÄÜ~D˜on~c~…%~Ópict~„™~DÚ~H›be~šplayed~†ëctly,~ªout~ÄŠ~Æfwhite dots~Vvertical lines (some~y faint grey res~/re ~~DÂs possibl~†w~Dla~Ö~›uses mor~–fferen~„šlors~×~Gƒarefu~„touch~Ûground (~ÅØs~…fix~Åhe metal cover)~F„~~Ê™~/disable-~‡S(if present)~M1re~‰öfunctio~DÃ~Ähe original~„Æte, s~at~Œ÷~'~OL~FCagain~Å×~…„~Ä÷ll~ˆ~~Œédis~‰†ll~†­~»~C~‰Žt~you~Ü~’re go~E$o do so). Drill a~†spond~!hole~Åñhe b~Ä›panel~„(empty)~„tom~Fd~‚fix~ÆØ~uin ~E~Åðyou want~zal~E)~…þifica~EVof video output (described later),~<it now (~ÄÏt~¡egin)~ÄÍTak~Fq~‹, ~Lit~Èo~Hºboard~Î1at e~„Òth~Dis OK. T~D¿~—4~‡"lead~´~Ç<~w~Åwher~ sid~˜odulator (~E+m~D³~­box~†«TV~G)~GÚt must~Äºfre~ÄHnot~…¬sed under~
w. Look~Æroug~†úventil~Ff~DÛs, examin~–posi~H‚upgrad~f~Êbe ab~á1-2mm below~
s~¦~…¼ir~„•nd~Óparts~
½ar en~”(otherwise t~Æä~D¤a piece~†ins~D(~”tape~J·~ÆÔ. Bend~7 points~E~ˆ‚~Fi~ÄTs~ˆ…(It's~¦ways bett~D7o~Ìßshiel~…ÿ~Ato~ÆPcompu~1- w~Ä¬possibl~D&~î~D~ row~D7out, as many authors~Ödifferent expansions are advising. It seem~Ïbe senseless, but~}~ÄÊll~H9listen~…ž~DÓple a radi~Ûcei~Éclo~Dj~Í(un~êed)~Út~]~…Vst~Ýwha~E:~Uinter~Æce...)›  Now~EÀ~ÉW~F:~ttom~D„stic~GX(~…ç~new ~ÆL~‡ì~DÂit~Æ~!original 7 screws. Sol~ˆò~Æ˜rom~~IT~†.one ~„%~Ç•~g~Çñonnec~±~…Š~)to ground~Æœlarge~‡Éareas ~„~ã,~Ee~9~Ž?~5~í~DQve j~Äinstalled). Ad~†Àkey~F4carefully~Çönsert~…Âleads~JT~yor. (T~©~~Åfp~D›ctly matc~FCcontacts. While~Y~§it, hol~ˆflat ca~„Õ~‰/~	j~“don't us~ëarp tools or nails.) F~D«ly a~Ütop~F~VÝ4~IÔCheck if everyth~žworks~9..~Ä's finished!›~†v~~mitio~„%informa~~Åmo~Æ\anced guys is follow~Ån~D?basic idea behi~„	his upgrade~1tha~‡Ýad GTIA chip~Æºdisplay~±~…5eft half~„weach pixe~„rr~E™~F
only~0righ~1is~`(low~„ßwo b~DýORe~ÇPhig~„«~)~Ä,~B~¨~…atake~ˆ~p~Äžit ~…‘~
s.› ~Esche~D6c diagram~Œshow~ÄJ figure 3~F.lumin~DP goes out~Æ~Ei~Æ!~D…~D 4 digi~Äsignals (4~¿The~„H~~DJgo~FEroug~† 74HCT75, which~•a D-type regist~„Ygiv~8a di~Db input-to-out~÷~‡Ä~„dur~H¨whole time~©a~„óck pulse~œ~„&eat~øa~„-s easy~Díabl~Dof~R}by keep~c~S~s active. Not~D¡at~†3~M~«ed~Ä|~_-~FÔowe~git (LUM0) need~Ä“to b~?~…ded (remember -~D”GRAPHICS 9 i~ÄG~)~†~ 10~!allways zero)~ˆ&~K#s (~Eèirst 1/4~FD~…ê)~Êmbined~†OSC~kPhi1. Becaus~†§~z~?~F	mov~F~…¬~†è~=~FN m~Ene inver~ðdepend~E˜~†‚~Fo mode. (I~corner~¬~ˆÓ, you can examin~ÄÏfferent~ï~IŸvailabl~u~Mmputer.~™2 may no~–used here, b~ëdelay between~Î~G2~„Ú~=st~ben~Å- some~„£s~Ä¼m~Å·g~×fals~N.) Whe~šhigh~„(two~Åm~ñPRIOR ($D01B~F¢~*same~DÊa~Dô~J‹1, or no~ÆÔ~DD)~w~b~Æe-swit~Æ˜"ON"~F§~L7~Å²~‡K~F’, s~„Úat~Ìà does~„Çchang~›~Fx~ˆ|~*4~Q 2-~Äregister, mak~Dûa copy~Åšwo~I~E~G´~E~Äße circuit around~`138~ÆÉdetects~4mom~„of writ~hdata~È¡address ~EY.››  Unfortunately~Golor~H~‹)~Ê°in such a simple way~Š>it goes out~ÆP~E˜~Ôform~†Ó~^PAL~i.›› -~•~òsecond~Ehe~E#problems ~âio~Ä¯~G™begin was TV synchroniza~&. As far as I know~æis~O occurs~ÄŠall XE's. D~Ð¡type~ŒTV/monitor~Ä‹'r~Ä?ing,~…òay happ~…v~šscr~Ä?~„sflying" a~Dä~…¡even~F+into~Æ?h~ulik~„¶ago~D%lines - mostly~×played picture~gbr~Äx. On~0~±~Å–~ˆ»~¨, but~se~DX~¶my~DEis extremely sensi~Ä~D¾~M=..~ˆòreaso~éinsid~ÆXE -~	output~Ëg~„Sfully~ˆV~†çworst ca~„Fs with~?video-~>~G’DIN~W~Æal~Å«e "antenna"~v~Ä…ff~†º~E}~lmono~„)m~È¾ (~Davailable~ˆ³~jconnector)~OOK,~„Owell~~„8~ls~†ñan XL-~…4computer~ÅmTo~ï~MF,~„L need on~DKsis~„b220 Ohm, a~Ä	ne PNP tran~ . (I used BC556~Ì's easily~Î~Echeap around here~H<~…,any univers~Äœ~m~Ãshould~Dœk.)›  O~†â~
Ü (as described~H7previous~ÄÊ~Ä‰)~Èlook~È¸corner~ÄXXE-board,~„ß~†Ê~!TV modula~ïAs~Œwn~„fig~„ò4~F<~£cut~E(way~csolder ~„“~€t~Ä?ad~	~Jk~~KZThes~áonent~y~bb~R~E¬t~†rterminals~Ê~	°~o~‡9ed~†Îa wire ~9other e~DÞf~~¹you've~Ì-~„^~	ó~!~÷. Not~Äe~IJ~	ªmay~Å_protrude abov~Ælevel~¥'s top~E -~‰A~Žshielding cove~Df~Dîtest~~un~EÝ, clos~f~ˆ~Å$~Š~‡. (You~¤~Åm~H²~r~	˜ legs instea~Mon PCB~F\~«~GÆ~F~‰E~8at long~Ey. But sinc~Hgs are qui~EOick~[h~…Œ~D‹ll~Æša very good tool~ž~ÆÆcase~ÅIt~Ì,~Eño~àf~Èés~HC~¡all~FFis simple upgra~„©~…utp~­gnal from~r XE~Äcorrect f~„½ll TV's~Åmight meet~Äfriends or~Ê®parties, just lik~F~p~ian XL.››  Mo~ÄŽnforma~Dé:~Ä~Ð~Ûorig~„ý~˜~C~Å½~È€iz~EÞsynchroniz~G pulses~+reduced~Åt mono~(m~	(~ê)~öpied~¤~^XL~FÒ~À~‰~ÈÕs~Emix~†Âlo~Dx~Çz~Å0s~Dôvideo~mwer~„Oplac~Ê²different typ~ÍTV~‹ª~…e XE. It's a bit bet~Dlsolu~ð(~v~…~FÒ~†x~Ä©go~¡back ~ž~Q), b~çre~cno~ tran~ì~„R~ÄÄ~ÎE(se~figure), s~a~G›whol~D¡~…`is moved m~Dñthan 0.5V down~Éùhat~†œ~WÎ~‡þrun~Fjnegative voltag~„t~Ç~È€i~… i~DŠsibl~øtays~ÄÖzero -~Å–~†+~‚.› ~…@added~Ms~†çmov~Æn~	òup~F•men~Bed >~ò) bef~F~KK~N:~Šè~‡.›› -››P.S. If~ÄŒ've go~3~Äext~Ïdisk,~ll find~K¡s~„Mseparat~les -~ˆa~Äƒ~„}GRAPHICS 8 pict~7.››