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- -----------------------------
- -╚OW TO ADD 8K ╥┴═ TO A 1541-
- -----------------------------
-
- ╞ILENAME: "EXPAND1541/8K"
-
- ┬Y ┴NDREW ┼. ═ILESKI
- "╥ECURSION" ON ╤-╠INK
- 210-180 ╠EES ┴VENUE
- ╧TTAWA, ╧NTARIO
- ├ANADA ╦1╙ 5╩6
-
- ├OPYRIGHT
- ═ARCH 24, 1990
-
-
- ╬OTE: ╘HIS IS FOR EXPERIENCED HARDWARE
- ----- HACKERS ONLY! ╨ROCEED ENTIRELY AT
- YOUR OWN RISK, AND YOU CAN KISS
- THE WARRANTY GOODBYE!
-
- ╘HIS IS BASED ON A 1984 ╥EVISION ┴
- CIRCUIT BOARD, BUT THERE SHOULD BE
- ENOUGH INFO HERE TO DO THE EXPANSION ON
- ANY 1541 DRIVE WITH VERY LITTLE WORK,
- AND ONLY A LITTLE THOUGHT.
-
- ╚INTS FOR OTHER VERSIONS OF CONTROLLER
- BOARDS: ╞IGURE OUT WHICH ╥╧═ IS ╥╧═0
- ($├000-$─╞╞╞) AND ╥╧═1 ($┼000-$╞╞╞╞).
- ┘OU ═┴┘ HAVE TO BEND PIN 20 OF EACH
- ╥╧═ 180 DEGREES TO THE VERTICAL; THIS
- IS THE *╥╧═X PIN. ╔GNORE STEPS 13, 14,
- 15, AND 16.
-
- ╘HIS MAY NOT BE THE EASIEST OR BEST WAY
- TO ADD ╥┴═, BUT IT DOES WORK. ╙ERIOUSLY
- CONSIDER BUYING ONE OF THE ╥┴═ BOARDS
- ON THE MARKET TODAY. ╘HEY ARE EASY TO
- INSTALL.
-
- !!!!!!!!!!!!!!!╫┴╥╬╔╬╟!!!!!!!!!!!!!!!!!
- ┘OU'LL BE HANDLING VERY ┼╙─ SESITIVE
- DEVICES! ═AKE SURE YOU AND YOUR TOOLS
- ARE PROPERLY GROUNDED AT ALL TIMES!
- (╔F YOU DON'T KNOW WHAT ┼╙─ STANDS FOR,
- DON'T EVEN THINK ABOUT TRYING THIS!!)
- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
- ┴N ASTERISK * BEFORE A SIGNAL MEANS IT
- IS ACTIVE LOW.
-
- ╞EEL FREE TO CONTACT ME IF YOU NEED
- SOME HELP, OR HAVE A PROJECT IDEA.
- (╔F IT WAS NOT FOR ╥AYMOND─2 ON ╤-LINK
- ASKING HOW TO ADD 8K TO HIS 1541, ╔
- NEVER WOULD HAVE WRITTEN THIS FILE!
- ╘HANKS ╥AYMOND!)
-
- ╬OTE: ╔ DID THIS MODIFICATION ON MY
- OWN DRIVE. ╔T DOES WORK. ╔ MODIFIED IT
- SLIGHTLY; ╔ NOW HAVE 32K ╥┴═ INSTALLED!
-
- ***************************************
- 1) ─ECIDE TO ADD 8K OR 32K. ═OST OF
- TODAYS SOFTWARE USES ONLY 8K, BUT
- WHO KNOWS WHAT MAY BE IN STORE FOR
- THE FUTURE! ╞OR 32K, IGNORE THIS
- ARTICLE, AND READ THE FILE
- "EXPAND1541/32K".
- 2) ╧BTAIN THE PARTS:
- ╘WO 74╠╙138 (3 TO 8 LINE DECODER)
- ╧NE 6264 (8K STATIC ╥┴═, 120NS)
- (NOTE THAT A 62╠╨64 IS LOW-POWER)
- ┴ SMALL PIECE OF PRE-DRILLED BOARD.
- ╘WO 16 PIN WIRE-WRAP SOCKETS IF YOU
- ARE GOING TO WIRE-WRAP THE CIRCUIT.
- 3) ╧PEN THE DISK DRIVE CASE AND REMOVE
- THE ╥╞ SHEILD.
- 4) ═ARK ONE END OF ┴╠╠ CONNECTORS WITH
- A MARKER, SO THAT YOU WILL BE ABLE
- TO REPLACE THEM LATER.
- 5) ╒NPLUG ┴╠╠ CONNECTORS.
- 6) ╒NSCREW THE CIRCUIT BOARD. ─ON'T
- FORGET THE SCREWS THAT ATTACH THE
- HEATSINK TO THE FRAME.
- 7) ╠IFT THE CIRCUIT BOARD OUT OF THE
- DISK DRIVE AND PLACE IT ON YOUR
- ANTI-STATIC CONDUCTIVE MAT (OR IF
- YOUR DESPERATE, A FOLDED TOWEL
- WILL DO!) COMPONENT SIDE UP, AND
- IN THE SAME ORIENTATION (TOP OF
- BOARD IS TOWARDS BACK OF DRIVE).
- 8) ╞IND THE 6116 (2K BY 8 BIT ╥┴═) ON
- THE CIRCUIT BOARD (24 PINS AND NOT
- SOCKETED, LEFT SIDE AT THE BACK).
- 9) ╧N THE NEW ╥┴═ CHIP TO BE ADDED
- CAREFULLY BEND THE FOLLOWING PINS
- 180 DEGREES, SO THAT THEY ARE
- POINTING IN THE OPPOSITE DIRECTION:
- PIN 2, 20, 22, 23, 27, AND 28.
- ╘HESE ARE THE SIGNALS ┴12, *├╙,*╧┼,
- ┴11, *╫┼ AND +5 VOLTS.
- ┬REAK OFF PIN 1; WE DON'T NEED IT.
- 10) ╙IT THE NEW ╥┴═ CHIP ON TOP OF THE
- 6116 CHIP. ╘HE BOTTOM PINS SHOULD
- BE ALIGNED. ═AKE SURE THAT BOTH OF
- THE CHIPS HAVE THEIR TOP-OF-CHIP
- REFERENCE MARKS POINTING IN THE
- SAME DIRECTION.
- 11) ├AREFULLY SOLDER THE TWO CHIPS PINS
- TOGETHER SO THEY ARE PIGGY-BACKED.
- ┬E CAREFULL TO AVOID SOLDER BRIDGES
- BETWEEN PINS.
- 12) ╠OCATE THE TWO 8K ╥╧═ CHIPS ON THE
- CIRCUIT BOARD (24 PINS AND SOCKETED
- ON RIGHT OF 6116).
- 13) ╘O THE RIGHT OF THE ╥╧═S, BETWEEN
- THE CHIPS AND THE HEATSINK, YOU
- WILL SEE 3 SILVER DOTS ON THE ╨├┬.
- ╘HESE ARE PASS-THROUGHS TO THE
- OTHER SIDE OF THE BOARD.
- 14) ╞LIP THE BOARD OVER, AND AGAIN FIND
- THE SAME 3 PASS-THROUGHS.
- 15) ├UT THE TRACE LEADING TO THE FRONT
- 2 PASS-THROUGHS (THE ONES TOWARDS
- THE FRONT OF THE DRIVE). ╘HE *╥╧═0
- AND *╥╧═1 SIGNALS REPLACE THE
- ORIGINAL ╥╧═ CHIP SELECTS THAT GO
- TO PIN 20 ON THE ╥╧═S, THAT IS WHY
- YOU MUST CUT THE TRACES!
- 16) ╙OLDER A WIRE INTO THE FRONT PASS-
- THROUGH; THIS ISαTHE *╥╧═0 SIGNAL
- ╙OLDER A WIRE INTO THE MIDDLE PASS-
- THROUGH; THIS IS THE *╥╧═1 SIGNAL
- ╘HE WIRES SHOULD BE LONG ENOUGH TO
- REACH THE FRONT OF THE BOARD PLUS
- ABOUT FOUR INCHES.
- 17) ╞IND THE 6502 ├╨╒ CHIP (40 PINS, ON
- THE RIGHT OF THE BOARD). ╙OLDER
- WIRES TO PINS 8, 20, 21, 22, 23,
- 24, 25, 34 AND 39. ╘HESE ARE THE
- SIGNALS +5 VOLTS, ┴11, GROUND, ┴12,
- ┴13, ┴14, ┴15, ╥/*╫, AND THETA2.
- ╙OLDER TWO WIRES TO PIN 34 SO YOU
- CAN CONNECT THE ╥┴═ CHIP.
- 18) ╧N A SMALL (1.25X1.75 INCH) PIECE
- OF CIRCUIT BOARD, WIRE-WRAP THE ╔├S
- OR USE POINT-TO-POINT SOLDERING.
-
- ╔├1, A 74╠╙138
- PIN
- 1 ┴14 16 +5 VOLTS
- 2 ┴15 15
- 3 ╟ROUND 14
- 4 ╟ROUND 13 6264 PIN 20
- 5 ╟ROUND 12 ╔├2 PIN 4
- 6 ╘HETA2 11
- 7 10
- 8 ╟ROUND 9
-
- ╔├2, A 74╠╙138
- PIN
- 1 ┴13 16 +5 VOLTS
- 2 ╟ROUND 15 *╥╧═0
- 3 ╟ROUND 14 *╥╧═1
- 4 ╔├1 PIN 12 13
- 5 ╟ROUND 12
- 6 ╥/*╫ 11
- 7 10
- 8 ╟ROUND 9
-
- 19) ├ONNECT THE 6502, ╥╧═S, AND ╥┴═
- CHIP SIGNALS TO THE 74╠╙138S.
- ╥UN THE WIRES TO THE FRONT, RIGHT
- OF THE BOARD (SEE BELOW FOR ╥┴═).
-
- ├ONNECT ╥┴═ PIN 2 (┴12) TO THE 6502
- PIN 22 (┴12) WIRE.
- ├ONNECT ╥┴═ PIN 20 (*├╙) TO ╔├1 PIN
- 13 (*├╙).
- ├ONNECT ╥┴═ PIN 22 (*╧┼) TO PIN 14
- (╟ROUND) OF THE CHIP WITH A SMALL
- WIRE.
- ├ONNECT ╥┴═ PIN 23 (┴11) TO THE
- 6502 PIN 20 (┴11) WIRE.
- ├ONNECT ╥┴═ PIN 27 (*╫┼) TO THE
- 6502 PIN 34 (╥/*╫) WIRE.
- ├ONNECT ╥┴═ PIN 28 (+5 ╓OLTS) TO
- 6116 PIN 24 WITH A SMALL WIRE.
-
- ╥UN THESE WIRES TO THE LEFT OF THE
- BOARD, AND AROUND TO THE SOLDER
- SIDE.
-
- 20) ╥EPLACE THE DRIVE CONTROLLER BOARD
- IN THE DRIVE, AND MOUNT THE NEW
- SMALL CIRCUIT BOARD TO THE FRAME
- WITH A SMALL MACHINE SCREW.
- 21) ┬┼╞╧╥┼ YOU SCREW THE DRIVE BOARD IN
- PLACE, MAKE SURE THE WIRES ARE NOT
- NEAR THE DRIVE OR TRANSFORMER, AND
- TAPE THEM IN PLACE TO THE BOTTOM OF
- THE BOARD.
- 22) ╙CREW THE DRIVE CONTROLLER BOARD TO
- THE FRAME AGAIN.
- 23) ╨LUG IN ALL THE CONNECTORS AGAIN.
- ├HECK YOUR REFERENCE MARKS.
- 24) ╨LUG THE DRIVE IN, AND TEST TO MAKE
- SURE THE DRIVE STILL WORKS NORMALLY
- 25) ╔F OKAY, THEN REPLACE ╥╞ SHIELD AND
- CASE COVER. ╔F NOT, POWER-DOWN AND
- CHECK ALL YOUR CONNECTIONS!
- 26) ╨AT YOUSELF ON THE BACK, YOUR DONE!
- ┘OU KNOW HAVE 8K ╥┴═ EXTRA!
-
- ╘HE 8K YOU INSTALLED IS AVAILABLE
- AT $8000-$┬╞╞╞ (A 16K SEGMENT)
- ╞OR EXAMPLE:
- $8000-$9╞╞╞,$9000-$┴╞╞╞,$A000-$┬╞╞╞
- ╫ILL ALL GIVE YOU ACCESS TO THE
- SAME 8K OF ╥┴═.
-
- ╥╧═0 AVAILABLE AT: $├000-$─╞╞╞
- ╥╧═1 AVAILABLE AT: $┼000-$╞╞╞╞
- ╘HE ╥╧═S ARE READ ONLY, AS THEY
- SHOULD BE.
- ***************************************
- ╫HAT DOES WHAT
- --------------
-
- ╔├1 DECODES THE 64K ADDRESS SPACE OF
- THE 6502 INTO FOUR 16K SEGMENTS, AND
- ALSO SYNCHRONIZES TO THE SYSTEM CLOCK
- THETA2. ╘HIS ╔├ SELECTS THE ╥┴═ CHIP
- DIRECTLY.
-
- ╔├2 DECODES ONE OF THE ABOVE MENTIONED
- 16K MEMORY SEGMENT TO TWO 8K SEGMENTS,
- AND ONLY ALLOWS READ CYCLES TO OCCUR.
- ╘HIS ╔├ SELECTS EACH ╥╧═ CHIP.
-
- ╫HY THIS WAY?
- -------------
-
- ╔ DID THINGS THIS WAY SO THAT THE 8K
- OF EXTRA ╥┴═ WOULD BE AVAILABLE IN
- THE LARGEST SEGMENT OF MEMORY POSSIBLE.
- ╘HIS IS TO ALLOW COMPATIBLITY WITH AS
- MUCH SOFTWARE AS POSSIBLE.
-
- ╬OTE THAT ╔ DIDN'T HAVE ANY SCHEMATICS
- FOR THE 1541, SO THIS METHOD IS MOST
- LIKELY NOT THE BEST. ╔ ALSO DIDN'T HAVE
- A VERY WIDE SELECTION OF ╔├S ON HAND AT
- THE TIME, SO ╔ USED WHAT ╔ HAD!
-
- ╔N OTHER WORDS, IF YOU KNOW OF A BETTER
- METHOD SHARE IT WITH THE REST OF US!
- ***************************************