ËEVIN ÄOWHOWER
   Ã-128 ÕSER
   ËÄ. ÇENIE

ÒÅ: ÁDDING AN EXTRA ÓÉÄ 6581 CHIP
ÌIBRARY # 13091

 ÆIRST, É WOULD LIKE TO SAY TO ÍARK Á. ÄICKENSON AND ÃHARLIE ÙOUNG, GOOD JOB!
ÔHIS IDEA FREES UP THE EXPANSION SLOT, REDUCES ÒÆ SHIELDING REQUIREMENTS, SHORTENS THE ADDRESS LINES WHICH REDUCES ERRORS, AND THOSE TWO ÒCA PHONO PLUGS LOOK 
SO SLICK STICKING OUT OF THE BACK OF MY Ã-128!
 ÄOWN TO BUSINESS. É HAVE ALWAYS USED MY ÒAMÌINK WITH MOST ALL OF MY MUSIC FILESBECAUSE IT MAKES FOR ALMOST INSTANTANEOUS LOADING OF FILES( É HAVE 193 FILES IN MY ÎATIVE PARTITION OF 4096 BLOCKS AND STILL HAVE ROOM FOR MORE!). É THEN BUILT MY OWN EXTERNAL ÓÉÄ BOARD TO GET STEREO SOUND BUT NOTICED THAT THERE WAS QUITE A BIT OF ÒÆ INTERFERENCE THAT É COULDN'T SEEM TO GET RID OF WITH NORMAL ÒÆ 
REDUCTION PRACTICES. É ALSO HAD TO COMPENSATE FOR THE LACK OF A +12 VOLT LINE
ON THE EXPANSION BUS. ÔO CIRCUMVENT THIS, É BUILT ONTO THE BOARD AN AMPLIFIER TOBOOST THE LEVEL TO MATCH THAT OF THE EXISTING ÓÉÄ CHIP. ÎEW PROBLEM CREATED BY 
THE AMPLIFIER; ÌOUDER ÒÆ NOISE! É COULD HEAR THE ÃÐÕ AND SERIAL BUS ACCESSES!
ÔHIS IS PRETTY NEAT FOR A WHILE BUT IF YOU APPRECIATE A LITTLE FIDELITY, DON'T
USE AN EXTERNAL BOARD OF ANY KIND. ÔHE FOLLING WILL DESCRIBE THE STEPS NECESSARYFOR USING THIS INTERNAL SECOND ÓÉÄ 6581 CHIP WITH THE BENEFITS OF ÒA.
 ÆIRST, INSTALL THE SECOND ÓID CHIP AS DESCRIBED IN FILE # 13091 WITH THE 
FOLLOWING EXCEPTIONS; 
                     1. ÄO NOT USE PIN 7 OR PIN 10 OF THE CARTRIDGE EXPANSIO
                       SLOT. ÉNSTEAD, YOU WILL USE THE ÒAMÌINK EXPANSION SLOT'S
                       PINOUTS 7 OR 10( É USE PIN 7). 
                     2. ÔHIS INSTALLATION WILL ONLY WORK WITH THE Ã-1 SINCE
                       IT DOESN'T REQUIRE THE TIMING CONNECTOR (ÓMALL, TWO 
                       TERMINAL PLUG ON THE ÒAMÌINK BOARD ABOVE THE EXPANSION
                       EDGE CARD). ÌOCATE THE COPPER TRACE LEADING TO THIS
                       PLUG AND USING A SHARP KNIFE, CUT THE TRACE UNTIL YOU
                       BREAK THE CONNECTION. ÂOTH TERMINALS ARE FED BY THE 
                       SAME TRACE (ÁÔ ÌÅÁÓÔ ÏÎ ÍÙ ÒAMÌINK) SO ONCE THIS IS
                       COMPLETED, US AN OHMMETER TO ASSURE AN ÏÐÅÎ CONDITION
                       EXISTS. ÔHIS ACT WILL PROBABLY VOID YOUR WARRANTY SO É
                       WOULD WAIT UNTIL IT EXPIRES BEFORE DOING IT! 
                        ÌOCATE PIN # 7 OR 10 ON THE ÒAMÌINK PASS-THRU POR WITH                       YOU FACING THE COMPUTER AND ÒAMÌINK IN THE INSTALLED 
                       POSITIPIN # 1 IS LOCATED ON THE ÌÅÆÔ-ÈÁÎÄ ÆÏ×ÁÒÄ
                       ÒÏ× OF PINS. ÔHIS IS TRUE OF BOTH Ã-64 AND Ã-128'S. ÃOUNT                       FROM PIN # 1 TO PIN # 7 OR 10 AND USING A 25 WATT OR LESS                       SOLDERING IRON, SOLDER A PIECE OF WIRE FROM THIS PIN TO                         THE TERMINAL CONNECTOR THAT YOU ISOLATED FROM ÒAMÌINK.
                       ÔHIS COMPLETES THE ÒAMÌINK MODIFICATIONS.
                     3. ÓOLDER THE LENGTH OF WIRE AND THE CONNECTOR GIVEN TO YOU                       WITH YOUR ÒAMÌINK TTHE ÄÐÓÔ SWITCH TERMINAL YOU WOULD                         HAVE INSTALLED TO THE COMPUTER'S CARTRIDGE EXPANSION 
                       SLOT.
                     4. ÕPON PLUGGING THE ÒAMÌINK INTO YOUR COMPUTER, PLUG THE
                       CONNECTOR INTO THE TWO TERMINAL PLUG FIRST AND THEN 
                       ÃÁÒÅÆÕÌÌÙ PLUG ÒAMÌINK INTO THE EXPANSION BUS SO AS NOT                         TO PINCH THE WIRE BETWEEN THE CASES.
                     5. ÂEFORE ASSEMBLY OF YOUR COMPUTER, YOU MAY CONSIDER 
                       BUILDING A SIMPLE ÌÅÄ DRIVER TO INDICATE TO YOU WHEN 
                       THE SECOND ÓÉÄ IS BEING ACCESSED. ËNOWING THAT THE CHIP
                       SELECT PIN (Ã/Ó) # 8 IS ÌÏ× WHEN ÔHE ÓÉÄ IS BEING 
                       ACCESSED, YOU SHOULD USE A ÐÎÐ TRANSITOR TO INVERT THE 
                       SIGNAL FOR THE ÌÅÄ. ÙÏÕ ÍÕÓÔ ÕÓÅ ÓÏÍÅ ÓÏÒÔ ÏÆ ÌÅÄ ÄÒÉÖÅÒ
                       ÔÏ ÁÖÏÉÄ ÏÖÅÒÌÏÁÄÉÎÇ ÔÈÅ Ã/Ó ÌÉÎÅ! ÍOUNT THE ÌÅÄ NEXT TO
                       THE SWITCH. ×ITH THIS SWITCH, YOU CAN VISUALLY SEE THE 
                       ÃÐÕ ACCESSING THE ÓÉÄ CHIP DURING AN ADDRESS. ÎÏÔÅ: ÔHE REASON FOR MODIFYING ÒAMÌINK WAS THAT WHEN TRYING TO BOOT THE COMPUTERWITH THE SECOND ÓÉÄ ENABLED, THE SYSTEM WOULD LOCK UP. ÉT SEEMS ÒAMÌINK USES 
BOTH É/Ï LINES PIN #'S 7 AND 10 FOR ITS OWN PURPOSES. ÉN FACT, DURING ANY TIME  WHILE USING MY COMPUTER, É COULD NOT US THE INTERNALLY INSTALLED SECOND ÓÉÄ CHIPAS INSTALLED BY THE ORIGINAL FILE #13091 UNTIL É REALIZED THAT THE EXTERNAL     BOARD É MADE WAS ACCESSED THROUGH THE PASS-THRU PORT ON ÒAMÌINK. ÔHE LIGHT CAME ON IN MY HEAD SO É USED A JUMPER TO THE PASS-THRU PORT Ã/Ó PIN # 7 AND E 
SWITCH TERMINAL. ÉT BOOTED UP NICELY AND EVERYTHING WORKED FINE. 
 ÏNE THING É DID NOTICED IS THAT É CANNOT USE ÓNAPÓHOT Ö5 WHILE THE SECOND ÓÉÄ  IS ENABLED BUT ONE THROW OF THE ENABLE/DISABLE SWITCH AND IT WORKS FINE. É 
SUSPECT THAT OTHER CARTRIDGES WILL HAVE SIMILAR TROUBLE SO THIS IS WHY É 
RECOMMEND THE ENABLE/DISABLE SWITCH. ÈAVE FUN!!!