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Text File | 1993-12-25 | 31.5 KB | 780 lines

three-key rollover FOR THE c-128 AND c-64. BY cRAIG bRUCE <CSBRUCE@NEUMANN.UWATERLOO.CA> 1. introduction tHIS ARTICLE EXAMINES A THREE-KEY ROLLOVER MECHANISM FOR THE KEYBOARDS OF THE c-128 AND c-64 AND PRESENTS kERNAL-WEDGE IMPLEMENTATIONS FOR BOTH MACHINES. wEBSTER'S DOESN'T SEEM TO KNOW, SO i'LL TELL YOU THAT THIS MEANS THAT THE MACHINE WILL ACT SENSIBLY IF YOU ARE HOLDING DOWN ONE KEY AND THEN PRESS ANOTHER WITHOUT RELEASING THE FIRST (OR EVEN PRESS A THIRD KEY WHILE HOLDING DOWN TWO OTHERS). tHIS IS USEFUL TO FAST TOUCH TYPERS. iN FACT, FAST TYPING WITHOUT ROLLOVER CAN BE QUITE ANNOYING; YOU GET A LOT OF MISSING LETTERS. aNOTHER ANNOYING PROPERTY OF THE KERNEL KEYSCANNING IS JOYSTICK INTERFERENCE. iF YOU MOVE THE JOYSTICK PLUGGED INTO PORT #1, YOU WILL NOTICE THAT SOME JUNK KEYSTROKES RESULT. tHE KEYSCANNERS HERE ELIMINATE THIS PROBLEM BY SIMPLY CHECKING IF THE JOYSTICK IS PRESSED AND IGNORING THE KEYBOARD IF IT IS. tHE REASON THAT A 3-KEY ROLLOVER IS IMPLEMENTED INSTEAD OF THE MORE GENERAL n-KEY ROLLOVER IS THAT SCANNING THE KEYBOARD BECOMES MORE AND MORE UNRELIABLE AS MORE KEYS ARE HELD DOWN. kEY "SHADDOWS" BEGIN TO APPEAR TO MAKE IT LOOK LIKE YOU ARE HOLDING DOWN A CERTAIN KEY WHEN YOU REALLY ARE NOT. sO, BY LIMITING THE NUMBER OF KEYS SCANNED TO 3, SOME OF THIS CAN BE AVOIDED. yOU WILL GET STRANGE RESULTS IF YOU HOLD DOWN MORE THAN THREE KEYS AT A TIME, AND EVEN SOMETIMES WHEN HOLDING DOWN 3 OR LESS. tHE "SHIFT" KEYS (sHIFT, cOMMODORE, cONTROL, aLTERNATE, AND cAPSlOCK) DON'T COUNT IN THE 3 KEYS OF ROLLOVER, BUT THEY DO MAKE THE KEYBOARD HARDER TO READ CORRECTLY. fORTUNATELY, THREE KEYS WILL ALLOW YOU TO TYPE WORDS LIKE "and" AND "the" WITHOUT RELEASING ANY KEYS. 2. user guide uSING THESE UTILITIES IS REALLY EASY - YOU JUST TYPE AWAY LIKE NORMAL. tO INSTALL THE c-128 VERSION, ENTER: boot "keyscan128" AND YOU'RE IN BUSINESS. tHE PROGRAM WILL DISPLAY "kEYSCAN128 INSTALLED" AND GO TO WORK. tHE PROGRAM LOADS INTO MEMORY AT ADDRESSES $1500-$17ba (5376-6074 DECIMAL), SO YOU'LL WANT TO WATCH OUT FOR CONFLICTS WITH OTHER UTILITIES. tHIS PROGRAM ALSO TAKES OVER THE irq VECTOR AND THE basic RESTART VECTOR ($a00). tHE PROGRAM WILL SURVIVE A run/stop+restore. tO UNINSTALL THIS PROGRAM, YOU MUST RESET THE MACHINE (OR POKE THE KERNEL VALUES BACK INTO THE VECTORS); IT DOES NOT UNINSTALL ITSELF. lOADING THE c-64 VERSION IS A BIT TRICKIER, SO A SMALL basic LOADER PROGRAM IS PROVIDED. load AND run THE "keyscan64.boot" PROGRAM. iT WILL LOAD THE "keyscan64" PROGRAM INTO MEMORY AT ADDRESSES $c500-$c77e (50432-51070 DECIMAL) AND EXECUTE IT (WITH A sys 50432). tO UNINSTALL THE PROGRAM, ENTER sys 50435. tHE PROGRAM TAKES OVER THE irq AND nmi VECTORS AND ONLY GIVES THEM BACK TO THE KERNEL UPON UNINSTALLATION. tHE PROGRAM WILL SURVIVE A run/stop+restore. sOMETHING THAT YOU MAY OR MAY NOT KNOW ABOUT THE c-64 IS THAT ITS KEYS CAN BE MADE TO REPEAT BY POKING TO ADDRESS 650 DECIMAL. poke650,128 WILL ENABLE THE REPEATING OF ALL KEYS. poke650,0 WILL ENABLE ONLY THE REPEATING OF THE space, delete, AND cursor KEYS. poke650,64 WILL DISABLE THE REPEATING OF ALL KEYS. aN UNUSUAL SIDE EFFECT OF CHANGING THIS TO EITHER FULL REPEAT OR NO REPEAT IS THAT HOLDING DOWN shift+commodore (CHARACTER SET SHIFT) WILL REPEAT RAPIDLY. tO SEE THE ROLLOVER IN ACTION, HOLD DOWN THE "j" KEY FOR A WHILE, AND THEN PRESS "k" WITHOUT RELEASING "j". "k" WILL COME OUT AS EXPECTED, AS IT WOULD WITH THE KERNAL. nOW, RELEASE THE "j" KEY. iF YOU ARE ON A c-128, YOU WILL NOTICE THAT THE "k" KEY WILL NOW STOP REPEATING (THIS IS ACTUALLY AN IMPORTANT FEATURE - IT AVOIDS PROBLEMS IF YOU DON'T RELEASE ALL OF THE KEYS YOU ARE HOLDING DOWN, AT ONCE). nOW, PRESS AND HOLD THE "j" KEY AGAIN WITHOUT RELEASING THE "k". "j" WILL NOW APPEAR. iT WOULDN'T USING THE kERNAL KEY SCANNER. yOU CAN ALSO TRY THIS WITH 3-KEY COMBINATIONS. tHERE WILL BE SOME COMBINATIONS THAT CAUSE PROBLEMS; MORE ON THIS BELOW. aLSO, TAKE A SPAZ ON THE JOYSTICK PLUGGED INTO PORT #1 AND OBSERVE THAT NO GARBAGE GETS TYPED IN. tHIS WAS AN ANNOYING PROBLEM WITH THE KERNEL OF BOTH THE 64 AND 128 AND HAS LEAD MANY DIFFERENT GAMES TO PICKING BETWEEN JOYSTICK #1 AND #2 AS THE PRIMARY CONTROLLER. tHE JOYSTICK IN PORT #2 IS NOT A PROBLEM TO EITHER kEYSCAN-128/64 OR THE kERNAL. 3. keyboard scanning tHE kERNAL SCANS THE KEYBOARD SIXTY TIMES A SECOND TO SEE WHAT KEYS YOU ARE HOLDING DOWN. bECAUSE OF HARDWARE PECULIARITIES, THERE ARE MULTIPLE SCANNING TECHNIQUES THAT WILL GIVE DIFFERENT RESULTS. 3.1. scanning example aN EXAMPLE PROGRAM IS INCLUDED TO DEMONSTRATE DIFFERENT KEYBOARD SCANNING TECHNIQUES POSSIBLE. tO RUN IT FROM A c-128 IN 40-COLUMN (SLOW) MODE, ENTER: boot "keyshow" oN A c-64, YOU MUST: load "keyshow",8,1 AND THEN: sys 4864 tHE SAME PROGRAM WORKS ON BOTH MACHINES. fOUR MAPS OF THE KEYSCANNING MATRIX WILL BE DISPLAYED ON THE 40-COLUMN SCREEN, AS SCANNED BY DIFFERENT TECHNIQUES. tHE LEFTMOST ONE IS SCANNED FROM TOP TO BOTTOM "QUICKLY". tHE SECOND FROM THE LEFT SCANS FROM BOTTOM TO TOP "QUICKLY". tHE THIRD FROM THE LEFT SCANS THE KEYBOARD SIDEWAYS, AND THE RIGHTMOST MATRIX SCANS THE KEYS FROM TOP TO BOTTOM "SLOWLY". tHE MAPPING OF KEYSCAN MATRIX POSITIONS TO KEYS IS AS FOLLOWS: rows: \ columns: PEEK($dc01) POKE \ $dc00 \ 128 64 32 16 8 4 2 1 +-------+-------+-------+-------+-------+-------+-------+-------+ 255-1 {$7c} down {$7c} f5 {$7c} f3 {$7c} f1 {$7c} f7 {$7c} right {$7c} return{$7c} delete{$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-2 {$7c}left-sh{$7c} e {$7c} s {$7c} z {$7c} 4 {$7c} a {$7c} w {$7c} 3 {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-4 {$7c} x {$7c} t {$7c} f {$7c} c {$7c} 6 {$7c} d {$7c} r {$7c} 5 {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-8 {$7c} v {$7c} u {$7c} h {$7c} b {$7c} 8 {$7c} g {$7c} y {$7c} 7 {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-16 {$7c} n {$7c} o {$7c} k {$7c} m {$7c} 0 {$7c} j {$7c} i {$7c} 9 {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-32 {$7c} , {$7c} @ {$7c} : {$7c} . {$7c} - {$7c} l {$7c} p {$7c} + {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-64 {$7c} / {$7c} ^ {$7c} = {$7c}rght-sh{$7c} home {$7c} ; {$7c} * {$7c} \ {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-128 {$7c} stop {$7c} q {$7c}commodr{$7c} space {$7c} 2 {$7c}control{$7c} _ {$7c} 1 {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ tHE FOLLOWING TABLE CONTAINS THE ADDITIONAL KEYS WHICH MUST BE SCANNED ON THE c128 (BUT WHICH ARE NOT DISPLAYED BY THE EXAMPLE SCANNING PROGRAM). rows: \ columns: PEEK($dc01) POKE \ $d02f \ 128 64 32 16 8 4 2 1 +-------+-------+-------+-------+-------+-------+-------+-------+ 255-1 {$7c} 1 {$7c} 7 {$7c} 4 {$7c} 2 {$7c} tab {$7c} 5 {$7c} 8 {$7c} help {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-2 {$7c} 3 {$7c} 9 {$7c} 6 {$7c} enter {$7c} lf {$7c} - {$7c} + {$7c} esc {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ 255-4 {$7c}no-scrl{$7c} right {$7c} left {$7c} down {$7c} up {$7c} . {$7c} 0 {$7c} alt {$7c} +-------+-------+-------+-------+-------+-------+-------+-------+ tHESE TABLES ARE PRESENTED ON PAGE 642 OF THE cOMMODORE 128 pROGRAMMER'S rEFERENCE gUIDE. tHE SCAN CODES THAT ARE STORED IN LOCATION 212 ON THE c128 AND LOCATION 197 ON THE c64 ARE CALCULATED BASED ON THE ABOVE TABLES. tHE ENTRY IN THE "1" BIT POSITION OF THE FIRST LINE OF THE FIRST TABLE (delete) HAS A SCAN CODE OF 0, THE "2" ENTRY (return) HAS A SCAN CODE OF 1, ETC., THE ENTRY ON THE SECOND SCAN LINE IN THE "1" POSITION ("3") HAS A SCAN CODE OF 8, ETC., ALL THE WAY DOWN TO CODE 63. tHE SCAN CODES FOR THE 128 GO ALL THE WAY TO 87, CONTINUING IN THE SECOND TABLE LIKE THE FIRST. yOU WILL NOTICE SOME STRANGE EFFECTS OF THE DIFFERENT SCANNING TECHNIQUES WHEN YOU HOLD DOWN MULTIPLE KEYS. mORE ON THIS BELOW. aLSO TRY PUSHING JOYSTICK #1 AROUND. 3.2. scanning hardware tO SCAN THE 128 KEYBOARD, YOU MUST POKE A VALUE INTO $dc00 (cia#1 PORT a) AND $d02f (vic CHIP KEYBOARD SELECT PORT) TO SELECT THE ROW TO BE SCANNED. tHE dATA dIRECTION rEGISTER FOR THIS PORT WILL BE SET TO ALL OUTPUTS BY THE kERNAL, SO YOU DON'T HAVE TO WORRY ABOUT IT. eACH BIT OF $dc00 AND THE THREE LEAST SIGNIFICANT BITS OF $d02f ARE USED FOR SELECTING ROWS. a "0" BIT MEANS THAT A ROW is SELECTED, AND A "1" MEANS THAT A ROW is not SELECTED. tHE POKE VALUE TO USE FOR SELECTING AMONG THE VARIOUS ROWS ARE GIVEN IN THE TWO TABLES IN THE PREVIOUS SECTION. uSING ONE BIT PER ROW ALLOWS YOU TO SELECT MULTIPLE ROWS AT THE SAME TIME. iT CAN BE USEFUL TO SELECT ALL ROWS AT ONE TIME OR NO ROWS. tO READ THE ROW THAT HAS BEEN SELECTED, SIMPLY PEEK AT LOCATION $dc01 (cia#1 PORT b). eACH BIT WILL TELL YOU WHETHER THE CORRESPONDING KEY IS CURRENTLY BEING HELD DOWN OR NOT. aGAIN, WE HAVE REVERSE LOGIC; A "0" MEANS THAT THE KEY IS BEING HELD DOWN, AND A "1" MEANS THAT THE KEY IS NOT HELD DOWN. tHE BIT VALUES CORRESPONDING TO THE KEYS ARE GIVEN AS THE COLUMN HEADINGS IN THE TABLES IN THE PREVIOUS SECTION. sINCE THERE IS NO SUCH THING AS A PERFECT MECHANICAL SWITCH, IT IS RECOMMENDED THAT YOU "DEBOUNCE" EACH KEY ROW READ IN THE FOLLOWING WAY: AGAIN: LDA $DC01 CMP $DC01 BNE AGAIN sO, TO SCAN THE ENTIRE KEYBOARD, YOU SIMPLY SELECT EACH SCAN ROW IN SOME ORDER, AND READ AND REMEMBER THE KEYS HELD DOWN ON THE ROW. aS IT TURNS OUT, YOU HAVE TO BE A BIT CAREFUL OF EXACTLY HOW YOU "SELECT" A ROW. aLSO, THERE IS A SHORTCUT THAT YOU CAN TAKE. iN ORDER TO FIND OUT IF ANY KEY IS BEING HELD DOWN IN ONE OPERATION, ALL YOU HAVE TO DO IS SELECT ALL ROWS AT ONCE AND SEE IF THERE ARE ANY "0" BITS IN THE READ VALUE. iF SO, THERE IS A KEY BEING HELD DOWN SOMEWHERE; IF NOT, THEN THERE IS NO KEY BEING HELD DOWN, SO YOU DON'T HAVE TO BOTHER SCANNING THE ENTIRE KEYBOARD. tHIS WILL REDUCE OUR KEYSCANNING SIGNIFICANTLY, WHICH IS IMPORTANT, SINCE THE KEYBOARD WILL BE SCANNED EVERY 1/60 OF A SECOND. aS MENTIONED ABOVE, JOYSTICK #1 WILL INTERFERE WITH THE kERNAL READING THE KEYBOARD. tHIS IS BECAUSE THE READ VALUE OF JOYSTICK #1 IS WIRED INTO cia#1 PORT a, THE SAME PLACE THAT THE KEYBOARD READ IS WIRED IN. sO, WHENEVER A SWITCH IN THE JOYSTICK IS PUSHED, THE CORRESPONDING BIT OF THE KEYBOARD SCAN REGISTER WILL BE FORCED TO "0", REGARDLESS OF WHICH KEYS ARE PRESSED AND REGARDLESS OF WHICH SCAN ROW IS SELECTED. tHERE'S THE CATCH. iF WE WERE TO UN-SELECT ALL SCAN ROWS AND STILL NOTICE "0"S IN THE KEYBOARD READ REGISTER, THEN WE WOULD KNOW THAT THE JOYSTICK WAS BEING PUSHED AND WOULD INTERFERE WITH OUR KEYBOARD SCANNING, SO WE COULD ABORT KEYBOARD SCANNING AND HANDLE THIS CASE AS IF NO KEYS WERE BEING HELD DOWN. iT STILL WOULD BE POSSIBLE BUT UNLIKELY THAT THE USER COULD PUSH THE JOYSTICK IN THE MIDDLE OF US SCANNING THE KEYBOARD AND SCREW UP OUR RESULTS, SO TO DEFEND AGAINST THIS, WE CHECK FOR THE JOYSTICK BEING PUSHED BOTH BEFORE AND AFTER SCANNING THE KEYBOARD. iF WE FIND THAT THE JOYSTICK IS PUSHED AT EITHER OF THESE TIMES, THEN WE THROW OUT THE RESULTS AND ASSUME THAT NO KEYS ARE HELD DOWN. tHIS WAY, THE ONLY WAY THAT A USER COULD SCREW UP THE SCANNING IS IF HE/SHE/IT WERE TO PRESS A SWITCH AFTER WE BEGIN SCANNING AND RELEASE IT BEFORE WE FINISH SCANNING. nOT BLOODY LIKELY FOR A HUMAN. yOU GET THE SAME DEAL FOR KEYBOARD SCANNING ON THE 64, EXCEPT YOU ONLY NEED TO USE $dc00 FOR SELECTING THE SCAN ROWS. aLSO NOTE THAT YOU WILL NOT BE ABLE TO PLAY WITH KEYBOARD SCANNING FROM basic BECAUSE OF THE INTERRUPT READING OF THE KEYBOARD. yOU MUST MAKE SURE THAT INTERRUPTS ARE DISABLED WHEN PLAYING WITH THE KEYBOARD HARDWARE, OR INTERRUPT SCANNING CAN COME ALONG AT ANY TIME AND CHANGE ALL OF THE REGISTER SETTINGS. 3.3. scanning source code tHE FOUR KEYBOARD SCANNING TECHNIQUES OF THE EXAMPLE PROGRAM ARE PRESENTED BELOW. tHE DECLARATIONS REQUIRED FOR ALL OF THEM ARE: PA = $DC00 ;ROW SELECT PB = $DC01 ;COLUMN READ DDRA = $DC02 ;DDR FOR ROW SELECT DDRB = $DC03 ;DDR FOR COLUMN READ SCANtABLE .BUF 8 ;STORAGE FOR SCAN MASK = $03 ;WORK LOCATION tHE CODE IS AS FOLLOWS, IN bUDDY FORMAT. eACH ROUTINE SCANS THE KEYBOARD AND STORES THE RESULTS IN THE "SCANtABLE" TABLE. ------------------+------------------+------------------+------------------+ rOW FORWARD FAST {$7c} rOW BACKWARD FAST{$7c} cOLUMN RIGHT {$7c} rOW FORWARD SLOW ------------------+------------------+------------------+------------------+ SEI {$7c} SEI {$7c} SEI {$7c} SEI LDX #0 {$7c} LDX #7 {$7c} LDA #$00 {$7c} LDX #0 LDA #$FE {$7c} LDA #$7F {$7c} STA DDRA {$7c} LDA #$FE STA PA {$7c} STA PA {$7c} LDA #$FF {$7c} STA MASK NEXTrOW = * {$7c} NEXTrOW = * {$7c} STA DDRB {$7c} NEXTrOW = * - LDA PB {$7c}- LDA PB {$7c} LDY #7 {$7c} LDA MASK CMP PB {$7c} CMP PB {$7c} LDA #$7F {$7c} STA PA BNE - {$7c} BNE - {$7c} STA MASK {$7c}- LDA PB EOR #$FF {$7c} EOR #$FF {$7c} NEXTcOL = * {$7c} CMP PB STA SCANtABLE,X {$7c} STA SCANtABLE,X {$7c} LDA MASK {$7c} BNE - SEC {$7c} SEC {$7c} STA PB {$7c} EOR #$FF ROL PA {$7c} ROR PA {$7c}- LDA PA {$7c} STA SCANtABLE,X INX {$7c} DEX {$7c} CMP PA {$7c} SEC CPX #8 {$7c} BPL NEXTrOW {$7c} BNE - {$7c} ROL MASK BCC NEXTrOW {$7c} CLI {$7c} LDX #$FF {$7c} INX CLI {$7c} RTS {$7c} STX PB {$7c} CPX #8 RTS {$7c} {$7c} EOR #$FF {$7c} BCC NEXTrOW ------------------+------------------+ LDX #7 {$7c} CLI {$7c}- ASL {$7c} RTS tHE FORWARD "QUICK" SCANNING STORES {$7c} ROL SCANtABLE,X +------------------+ THE SCAN ROW SELECTION MASK INTO {$7c} DEX {$7c} THE ROW SELECTION REGISTER AND {$7c} BPL - {$7c} SHIFTS THE "0" BIT ONE POSITION {$7c} SEC {$7c} "FORWARD" FOR EACH ROW, DIRECTLY, {$7c} ROR MASK {$7c} USING A "ROL $DC00" INSTRUCTION. {$7c} DEY {$7c} tHIS WOULD PROBABLY BE THE OBVIOUS {$7c} BPL NEXTcOL {$7c} SOLUTION TO AN OPTIMIZING ASSEMBLER {$7c} LDA #$FF {$7c} PROGRAMMER. hOWEVER, FOR SOME {$7c} STA DDRA {$7c} REASON NOT QUITE UNDERSTOOD BY THIS {$7c} LDA #$00 {$7c} AUTHOR, THERE ARE "SHADOWING" {$7c} STA DDRB {$7c} PROBLEMS WITH THIS APPROACH. iF {$7c} CLI {$7c} YOU WERE TO HOLD DOWN THE TWO KEYS {$7c} RTS {$7c} "h" AND "k" AT THE SAME TIME, YOU +------------------+ WOULD NOTICE THAT THESE TWO KEYS ARE ON THE SAME COLUMN OF TWO SUCCESSIVE ROWS. iF YOU HOLD THEM BOTH DOWN, YOU WILL SEE THE TWO POSITIONS BECOME ACTIVE, BUT SO WILL THE SAME COLUMN OF ALL SUCCESSIVE ROWS AFTER THE "h" AND "k", EVEN THOUGH THESE OTHER KEYS ARE NOT ACTUALLY HELD DOWN. yOU WILL GET AN INACCURATE READING IF BAD KEYS ARE HELD DOWN SIMULTANEOUSLY. yOU WILL NOTICE THE USE OF THE TERM "ACTIVE" ABOVE. tHIS IS BECAUSE ALTHOUGH THE HARDWARE RETURNS A "0" FOR ACTIVE, THE ROUTINE CONVERTS THAT INTO A "1" FOR EASIER PROCESSING LATER. i AM NOT SURE IF EVERYONE WILL GET THIS SAME RESULT, BUT IF YOUR KEYBOARD IS WIRED THE SAME AS MINE, YOU WILL. tHE BACKWARD "QUICK" SCANNING OPERATES QUITE SIMILARLY TO THE FORWARD SCANNING, EXCEPT FOR THE DIRECTION OF THE SCAN AND THE DIRECTION OF THE "SHADOW"; THE SHADOW GOES UPWARDS. yOU MIGHT THINK THAT andING TOGETHER THE RESULTS OF THE FORWARD AND BACKWARD SCAN TOGETHER WOULD ELIMINATE THE SHADOW, BUT THIS WILL NOT WORK SINCE ANY ROWS BETWEEN THE ROWS CONTAINING THE TWO KEYS HELD DOWN WILL BE INCORRECTLY READ AS BEING ACTIVE. tHE COLUMNWISE RIGHT SCANNING IS THE MOST COMPLICATED BECAUSE THE ROWS MUST BE CONVERTED INTO COLUMNS, TO ALLOW THE SCAN MATRIX TO BE INTERPRETED AS BEFORE. aLSO, THE dATA dIRECTION rEGISTERS HAVE TO BE CHANGED. yOU MIGHT THINK THAT COMBINGING ROW-WISE SCANNING WITH COLUMNWISE SCANNING WOULD GIVE BETTER RESULTS, AND IT PROBABLY WOULD, IF IT WEREN'T FOR A BIZARRE HARDWARE PROBLEM. iF YOU HOLD DOWN TWO OR MORE KEYS ON THE SAME SCAN ROW, SAY "w" AND "e", SOME OF THE KEYS WILL FLICKER OR DISAPPEAR, GIVING AN INACCURATE READING. tHE FORWARD "SLOW" SCANNING IS THE BEST OF THE BUNCH. iNCIDENTALLY, IT IS WHAT THE kERNAL USES (AS NEAR AS i CAN FIGURE - THEIR CODE IS EXTREMELY CONVOLUTED). tHIS TECHNIQUE IS THE SAME AS THE FORWARD "QUICK SCAN," EXCEPT THAT THE ROW SELECTION MASK IS SHIFTED IN A WORKING STORAGE LOCATION AND POKED INTO THE cia REGISTER, RATHER THAN BEING SHIFTED IN PLACE. i DON'T KNOW WHY THIS MAKES A DIFFERENCE, BUT IT DOES. tHERE IS STILL A PROBLEM WITH THIS TECHNIQUE, BUT THIS PROBLEM OCCURS WITH ALL TECHNIQUES. iF YOU HOLD DOWN THREE KEYS THAT FORM THREE "CORNERS" OF A RECTANGLE IN THE SCANNING MATRIX, THEN THE MISSING CORNER WILL BE READ AS BEING HELD DOWN ALSO. fOR EXAMPLE, IF YOU HOLD DOWN "c", "n", AND "m", THEN THE KEYBOARD HARDWARE WILL ALSO THINK THAT YOU ARE HOLDING DOWN THE "x" KEY. tHIS IS WHY THIS ARTICLE IMPLEMENTS A "THREE-KEY" ROLLOVER RATHER THAN AN "n-KEY" ROLLOVER. mANY THREE-KEY COMBINATIONS WILL STILL BE INTERPRETED CORRECTLY. nOTE, HOWEVER, THAT SHIFT KEYS SUCH AS shift OR control WILL ADD ONE MORE KEY TO THE HARDWARE SCANNING (BUT WILL NOT BE COUNTED IN THE THREE-KEY ROLLOVER), MAKING INACCURATE RESULTS MORE LIKELY IF YOU ARE HOLDING DOWN MULTIPLE OTHER KEYS AT THE SAME TIME. 4. the c-128 keyscanner tHIS SECTION GIVES THE SOURCE CODE FOR THE c-128 IMPLEMENTATION OF THE THREE-KEY ROLLOVER. tHE FORWARD "SLOW" KEY MATRIX SCANNING TECHNIQUE IS USED, EXTENDED TO WORK WITH THE EXTRA KEYS OF THE 128. iT WAS A BIT OF A PAIN WEDGING INTO THE kERNAL, SINCE THERE IS NOT A CONVENIENT INDIRECT jmp INTO SCANNING THE KEYBOARD, LIKE THERE ARE FOR DECODING AND BUFFERING PRESSED KEYS. a RATHER LENGTHY irq "PREAMBLE" HAD TO BE COPIED FROM THE rom, UP TO THE POINT WHERE IT jsrS TO THE KEYSCANNING ROUTINE. tHIS CODE IN INCLUDED IN THE FORM OF A ".BYTE" TABLE, TO SPARE YOU THE DETAILS. bEFORE SCANNING THE KEYBOARD, WE CHECK TO SEE IF JOYSTICK #1 IS PUSHED AND IF A KEY IS ACTUALLY PRESSED. iF NOT, WE ABORT SCANNING AND jmp TO THE KEY REPEAT HANDLING IN THE rom. iF A KEY IS HELD DOWN, WE SCAN THE KEYBOARD AND THEN EXAMINE THE RESULT. fIRST WE CHECK FOR THE SHIFT KEYS (shift, commodore, control, alt, AND caps lock), PUT THEM INTO LOCATION $d3 (SHIFT FLAGS) IN BIT POSTITIONS 1, 2, 4, 8, AND 16, RESPECTIVELY, AND REMOVE THEM FROM THE SCAN MATRIX. tHE caps lock KEY IS NOT ON THE MAIN KEY MATRIX; IT IS READ FROM THE PROCESSOR i/o PORT. tHIS IS GOOD, BECAUSE OTHERWISE WE COULD NOT ABORT SCANNING IF IT WERE THE ONLY KEY HELD DOWN. tHEN WE SCAN THE KEYMATRIX FOR THE FIRST THREE KEYS THAT ARE BEING HELD DOWN, OR AS MANY AS ARE HELD DOWN IF LESS THAN THREE. wE STORE THE SCAN CODES OF THESE KEYS INTO A 3-ELEMENT ARRAY. wE ALSO RETAIN A COPY OF THE 3-ELEMENT ARRAY FROM THE PREVIOUS SCAN AND WE CHECK FOR DIFFERENT KEYS BEING IN THE TWO ARRAYS. iF THE OLD ARRAY CONTAINS A KEY THAT IS NOT PRESENT IN THE NEW ARRAY, THEN THE USE HAS RELEASED A KEY, SO WE SET A FLAG TO INHIBIT INTERPRETATION OF KEYS AND PRETEND THAT NO KEYS ARE HELD DOWN. tHIS IS TO ELIMINATE UNDESIRABLE EFFECTS OF HAVING OTHER KEYS HELD DOWN REPEAT IF YOU RELEASE THE MOST RECENTLY PUSHED KEY FIRST. pc KEYBOARDS DO THIS. tHIS INHIBITING WILL BE IGNORED IF NEW KEYS ARE DISCOVERED IN THE NEXT STEP. iF THERE ARE KEYS IN THE NEW ARRAY THAT ARE NOT IN THE OLD, THEN THE USER HAS JUST PRESSED A NEW KEY, SO THAT NEW KEY GOES TO THE HEAD OF THE OLD ARRAY AND WE STOP COMPARING THE ARRAYS THERE. tHE KEY IN THE FIRST POSITION OF THE OLD ARRAY IS POKED INTO THE kERNAL "KEY HELD DOWN" LOCATION FOR THE kERNAL TO INTERPRET LATER. iF MORE THAN ONE NEW KEY IS DISCOVERED AT THE SAME TIME, THEN EACH OF THE NEW KEYS WILL BE PICKED UP ON SUCCESSIVE KEYBOARD SCANS AND WILL BE INTERPRETED AS JUST BEING PUSHED. sO, IF YOU PRESS THE "a", "n", AND "d" KEYS ALL AT THE SAME TIME, SOME PERMUTATION OF ALL THREE OF THESE KEYS WILL APPEAR ON THE SCREEN. wHEN WE ARE DONE INTERPRETING THE KEYS, WE CHECK THE JOYSTICK ONCE MORE AND IF IT IS STILL INACTIVE, WE PRESENT THE MOST RECENTLY PUSHED DOWN KEY TO THE kERNAL AND jmp INTO THE rom KEYBOARD DECODING ROUTINE. uNLIKE IN PREVIOUS ISSUES, THIS SOURCE CODE IS HERE IN LITERAL FORM; JUST EXTRACT EVERYTHING BETWEEN THE "-----=-----"S TO NAB THE SOURCE FOR YOURSELF. tHE SOURCE IS IN bUDDY ASSEMBLER FORMAT. -----=----- ;3-kEY rOLLOVER-128 BY cRAIG bRUCE 18-jUN-93 FOR c= hACKING MAGAZINE .ORG $1500 .OBJ "@0:KEYSCAN128" SCANROWS = 11 ROLLOVER = 3 PA = $DC00 PB = $DC01 PK = $D02F JMP INITIALiNSTALL ;UGLY irq PATCH CODE. IRQ = * ;$1503 .BYTE $D8,$20,$0A,$15,$4C,$69,$FA,$38,$AD,$19,$D0,$29,$01,$F0,$07,$8D .BYTE $19,$D0,$A5,$D8,$C9,$FF,$F0,$6F,$2C,$11,$D0,$30,$04,$29,$40,$D0 .BYTE $31,$38,$A5,$D8,$F0,$2C,$24,$D8,$50,$06,$AD,$34,$0A,$8D,$12,$D0 .BYTE $A5,$01,$29,$FD,$09,$04,$48,$AD,$2D,$0A,$48,$AD,$11,$D0,$29,$7F .BYTE $09,$20,$A8,$AD,$16,$D0,$24,$D8,$30,$03,$29,$EF,$2C,$09,$10,$AA .BYTE $D0,$28,$A9,$FF,$8D,$12,$D0,$A5,$01,$09,$02,$29,$FB,$05,$D9,$48 .BYTE $AD,$2C,$0A,$48,$AD,$11,$D0,$29,$5F,$A8,$AD,$16,$D0,$29,$EF,$AA .BYTE $B0,$08,$A2,$07,$CA,$D0,$FD,$EA,$EA,$AA,$68,$8D,$18,$D0,$68,$85 .BYTE $01,$8C,$11,$D0,$8E,$16,$D0,$B0,$13,$AD,$30,$D0,$29,$01,$F0,$0C .BYTE $A5,$D8,$29,$40,$F0,$06,$AD,$11,$D0,$10,$01,$38,$58,$90,$07,$20 .BYTE $AA,$15,$20,$E7,$C6,$38,$60 ;KEYSCANNING ENTRY POINT MAIN = * LDA #0 ;CHECK IF ANY KEYS ARE HELD DOWN STA PA STA PK - LDA PB CMP PB BNE - CMP #$FF BEQ NOkEYpRESSED ;IF NOT, THEN DON'T SCAN KEYBOARD, GOTO kERNAL JSR CHECKjOYSTICK ;IF SO, MAKE SURE JOYSTICK NOT PRESSED BCC JOYSTICKpRESSED JSR KEYSCAN ;SCAN THE KEYBOARD AND STORE RESULTS JSR CHECKjOYSTICK ;MAKE SURE JOYSTICK NOT PRESSED AGAIN BCC JOYSTICKpRESSED JSR SHIFTDECODE ;DECODE THE SHIFT KEYS JSR KEYDECODE ;DECODE THE FIRST 3 REGULAR KEYS HELD DOWN JSR KEYORDER ;SEE WHICH NEW KEYS PRESSED, OLD KEYS RELEASED, AND ; DETERMINE WHICH KEY TO PRESENT TO THE kERNAL LDA $033E ;SET UP FOR AND DISPATCH TO kERNAL STA $CC LDA $033F STA $CD LDX #$FF BIT IGNOREkEYS BMI ++ LDA PREVkEYS+0 CMP #$FF BNE + LDA $D3 BEQ ++ LDA #88 + STA $D4 TAY JMP ($033A) NOkEYpRESSED = * ;NO KEYS PRESSED; SELECT DEFAULT SCAN ROW LDA #$7F STA PA LDA #$FF STA PK JOYSTICKpRESSED = * LDA #$FF ;RECORD THAT NO KEYS ARE DOWN IN OLD 3-KEY ARRAY LDX #ROLLOVER-1 - STA PREVkEYS,X DEX BPL - JSR SCANcAPS ;SCAN THE caps lock KEY LDX #$FF LDA #0 STA IGNOREkEYS + LDA #88 ;PRESENT "NO KEY HELD" TO kERNAL STA $D4 TAY JMP $C697 INITIALiNSTALL = * ;INSTALL WEDGE: SET RESTORE VECTOR, PRINT MESSAGE JSR INSTALL LDA #<REINSTALL LDY #>REINSTALL STA $0A00 STY $0A01 LDX #0 - LDA INSTALLmSG,X BEQ + JSR $FFD2 INX BNE - + RTS INSTALLmSG = * .BYTE 13 .ASC "KEYSCAN128 INSTALLED" .BYTE 0 REINSTALL = * ;RE-INSTALL WEDGE AFTER A run/stop+restore JSR INSTALL JMP $4003 INSTALL = * ;GUTS OF INSTALLATION: SET irq VECTOR TO PATCH CODE SEI ; AND INITIALIZE SCANNING VARIABLES LDA #<IRQ LDY #>IRQ STA $0314 STY $0315 CLI LDX #ROLLOVER-1 LDA #$FF - STA PREVkEYS,X DEX BPL - LDA #0 STA IGNOREkEYS RTS MASK = $CC KEYSCAN = * ;SCAN THE (EXTENDED) KEYBOARD USING THE FORWARD LDX #$FF ; ROW-WISE "SLOW" TECHNIQUE LDY #$FF LDA #$FE STA MASK+0 LDA #$FF STA MASK+1 JMP + NEXTrOW = * - LDA PB CMP PB BNE - STY PA STY PK EOR #$FF STA SCANtABLE,X SEC ROL MASK+0 ROL MASK+1 + LDA MASK+0 STA PA LDA MASK+1 STA PK INX CPX #SCANROWS BCC NEXTrOW RTS SHIFTvALUE = $D3 SHIFTrOWS .BYTE $01,$06,$07,$07,$0A SHIFTbITS .BYTE $80,$10,$20,$04,$01 SHIFTmASK .BYTE $01,$01,$02,$04,$08 SHIFTDECODE = * ;SEE WHICH "SHIFT" KEYS ARE HELD DOWN, PUT THEM INTO JSR SCANcAPS ; PROPER POSITIONS IN $d3 (SHIFT FLAGS), AND REMOVE LDY #4 ; THEM FROM THE SCAN MATRIX - LDX SHIFTrOWS,Y LDA SCANtABLE,X AND SHIFTbITS,Y BEQ + LDA SHIFTmASK,Y ORA SHIFTvALUE STA SHIFTvALUE LDA SHIFTbITS,Y EOR #$FF AND SCANtABLE,X STA SCANtABLE,X + DEY BPL - RTS SCANcAPS = * ;SCAN THE caps lock KEY FROM THE PROCESSOR i/o PORT - LDA $1 CMP $1 BNE - EOR #$FF AND #$40 LSR LSR STA SHIFTvALUE RTS NEWPOS = $CC KEYCODE = $D4 XSAVE = $CD KEYDECODE = * ;GET THE SCAN CODES OF THE FIRST THREE KEYS HELD DOWN LDX #ROLLOVER-1 ;INITIALIZE: $FF MEANS NO KEY HELD LDA #$FF - STA NEWkEYS,X DEX BPL - LDY #0 STY NEWPOS LDX #0 STX KEYCODE DECODEnEXTrOW = * ;DECODE A ROW, INCREMENTING THE CURRENT SCAN CODE LDA SCANtABLE,X BEQ DECODEcONTINUE ;AT THIS POINT, WE KNOW THAT THE ROW HAS A KEY HELD LDY KEYCODE - LSR BCC ++ PHA ;HERE WE KNOW WHICH KEY IT IS, SO STORE ITS SCAN CODE, STX XSAVE ; UP TO 3 KEYS LDX NEWPOS CPX #ROLLOVER BCS + TYA STA NEWkEYS,X INC NEWPOS + LDX XSAVE PLA + INY CMP #$00 BNE - DECODEcONTINUE = * CLC LDA KEYCODE ADC #8 STA KEYCODE INX CPX #SCANROWS BCC DECODEnEXTrOW RTS ;KEYORDER: DETERMINE WHAT KEY TO PRESENT TO THE kERNAL AS BEING LOGICALLY THE ;ONLY ONE PRESSED, BASED ON WHICH KEYS PREVIOUSLY HELD HAVE BEEN RELEASED AND ;WHICH NEW KEYS HAVE JUST BEEN PRESSED KEYORDER = * ;** REMOVE OLD KEYS NO LONGER HELD FROM OLD SCAN CODE ARRAY LDY #0 NEXTrEMOVE = * LDA PREVkEYS,Y ;GET CURRENT OLD KEY CMP #$FF BEQ ++ LDX #ROLLOVER-1 ;SEARCH FOR IT IN THE NEW SCAN CODE ARRAY - CMP NEWkEYS,X BEQ + DEX BPL - TYA ;HERE, OLD KEY NO LONGER HELD; REMOVE IT TAX - LDA PREVkEYS+1,X STA PREVkEYS+0,X INX CPX #ROLLOVER-1 BCC - LDA #$FF STA PREVkEYS+ROLLOVER-1 STA IGNOREkEYS + INY ;CHECK NEXT OLD KEY CPY #ROLLOVER BCC NEXTrEMOVE ;** INSERT NEW KEYS AT FRONT OF OLD SCAN CODE ARRAY + LDY #0 NEXTiNSERT = * LDA NEWkEYS,Y ;GET CURRENT NEW KEY CMP #$FF BEQ ++ LDX #ROLLOVER-1 ;CHECK OLD SCAN CODE ARRAY FOR IT - CMP PREVkEYS,X BEQ + DEX BPL - PHA ;IT'S NOT THERE, SO INSERT NEW KEY AT FRONT, EXIT LDX #ROLLOVER-2 - LDA PREVkEYS+0,X STA PREVkEYS+1,X DEX BPL - LDA #0 STA IGNOREkEYS PLA STA PREVkEYS+0 LDY #ROLLOVER ;(TRICK TO EXIT) + INY CPY #ROLLOVER BCC NEXTiNSERT + RTS ;NOW, THE HEAD OF THE OLD SCAN CODE ARRAY CONTAINS ; THE SCAN CODE TO PRESENT TO THE kERNAL, AND OTHER ; POSITIONS REPRESENT KEYS THAT ARE ALSO HELD DOWN ; THAT HAVE ALREADY BEEN PROCESSED AND THEREFORE CAN ; BE IGNORED UNTIL THEY ARE RELEASED CHECKjOYSTICK = * ;CHECK IF JOYSTICK IS PUSHED: UN-SELECT ALL KEYBOARD LDA #$FF ; ROWS AND SEE IF THERE ARE ANY "0"S IN THE SCAN STA PA ; STATUS REGISTER STA PK - LDA PB CMP PB BNE - CMP #$FF LDA #$7F ;RESTORE TO DEFAULT kERNAL ROW SELECTED (TO THE ONE STA PA ; CONTAINING THE stop KEY) LDA #$FF STA PK RTS ;GLOBAL VARIABLES SCANtABLE .BUF SCANROWS ;VALUES OF THE ELEVEN KEYBOARD SCAN ROWS NEWkEYS .BUF ROLLOVER ;CODES OF UP TO THREE KEYS HELD SIMULTANEOUSLY IGNOREkEYS .BUF 1 ;FLAG: IF AN OLD KEY HAS BEEN RELEASED AND NO ; NEW KEY HAS BEEN PRESSED, STOP ALL KEY ; REPEATING PREVkEYS .BUF ROLLOVER+2 ;KEYS HELD ON PREVIOUS SCAN -----=----- aND THAT'S ALL THERE IS TO IT. :-) 5. the c-64 keyscanner tHE BOOT PROGRAM FOR THE c-64 KEYSCANNER IS AS FOLLOWS: 10 D=PEEK(186) 20 IF A=1 THEN 60 30 A=1 40 LOAD"KEYSCAN64",D,1 50 GOTO 10 60 SYS 49152+5*256 : REM $C500 iT IS VERY MUCH LIKE BOOT PROGRAMS FOR OTHER MACHINE LANGUAGE PROGRAMS THAT DON'T LOAD AT THE START OF basic. iT WILL LOAD THE BINARY FROM THE LAST DEVICE ACCESSED, AND ACTIVATE IT. a LISTING OF THE c-64 KEYSCANNING CODE IS NOT PRESENTED HERE BECAUSE IT IS SO SIMILAR TO THE c-128 LISTING. tHE ONLY THINGS THAT ARE DIFFERENT ARE THE kERNAL PATCHES AND THE KEYBOARD SCANNING (BECAUSE THE THREE EXTRA ROWS DON'T HAVE TO BE SCANNED). tHE irq HAD TO BE SUBSTANTIALLY COPIED FROM THE rom, AGAIN, TO GET AT THE CALL TO THE KEY SCANNING. aLSO, RATHER THAN TAKING OVER THE basic RESET VECTOR (SINCE THERE ISN'T ONE), THE nmi VECTOR IS TAKEN OVER TO INSURE THE SURVIVAL OF THE KEY SCANNER AFTER A run/stop+restore. a BIT OF ITS PREAMBLE ALSO HAD TO BE COPIED OUT OF rom TO GET AT THE GOOD STUFF. iF YOU WANT A COPY OF THE c-64 LISTING, YOU CAN E-MAIL ME. 6. uuencoded files hERE ARE THE BINARY EXECUTABLES IN UUENCODED FORM. tHE crc32S OF THE FOUR FILES ARE AS FOLLOWS: CRC32 = 3398956287 FOR "KEYSCAN128" CRC32 = 2301926894 FOR "KEYSCAN64.BOOT" CRC32 = 1767081474 FOR "KEYSCAN64" CRC32 = 1604419896 FOR "KEYSHOW" BEGIN 640 KEYSCAN128 m{$60}!5,'a;8({$60}h53&gz.*t9t"d!\{$60}>-&="ev,g_\&\l$={$60}p!"e{$60}t#$xi=cp+"38 m4{$60}:m-{$60}j-$m"e{$60}2g]"01(k2t*2*t1t"e_"2"hk1;0)-@p{$60}rgo+{$60}d0jm{$60}hj?^- m$m"e{$60}0d"*?l%v4bm+{$60}i(k1'0*5^hk1;0*>^jl{$60}bb!\k0_>kjjfb-&-!ha0&, m$=".%m"p$ztpt"d!\{$60}rev"e{$60}\{$60}:m$={$60}0{$60}3a8d{$60}<@ja4@y\8x8*d{$60}c0#<c2_0 mk0'<s0'<t/c)__{$60}z((d7d#\@<18@b1>0-r"w%b#l%b{$60}l%zt^{$60}x7,k3\#a<vb m_rrt%s{$60}qk;47r?_0!j73\":i6(74j&pz{$60}ze_c0#<j?^-+]"i_z("g;47ra#z m(-t6ho^i{$60}(vt%ze8a=2h3)?&(%46j4^@%ht{$60}"hp!"j({$60}o3d6\{$60}8@to_ht/5@ m#4m%65-#04xq,c@@24y35$%,3$5${$60}"!5%dp#0'bi{$60}z{$60}5c10#c!4#6*("j?^= mm1?*$/ji{$60}(vt%v"b_z#_j?z%s*g_a<u,f!:m{$60}=s-{$60}=s0^(p{$60}w(pot$g_g:87 m.";,)lves(t{$60}w*7-c2_0z.{$60}+d-e@{$60}08'!pj{$60}$"{$60}${$60}0$!{$60}@0((-t6h{$60}2^j!:] mia<yk1;p$kfr%@73a=.yk19)_svf%yvf%x@0x&"e{$60}<4!t/i)_re{$60}2dj%tv"b m{$60}jg_g;$7ra#zh{$60}"$s*({$60}am2]ia?p'*342i{$60}22(;-ils@{$60}[{$60}&f)vq%^;,iluh mr,d{$60}t.88i=1i"(74z.{$60}+d--@h{$60}"ym1?)__{$60}dh@+=l1?p&,h0^)bjo;87g;47 mz.{$60}"d/6i_xvw%xvt%\c{$60}{$60}y#5h{$60}"yl1?)__{$60}fh@+=m1?p&lh0^$bb{$60};vu%yvv m%\h0]zd{$60}c;07:(vu%z{$60}#r,{$60}#d--@j?^-{$60}-r-+]"m{$60}=s-{$60}=s0^,g_j7^-{$60}-ri 9_xtot&{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60} {$60} END BEGIN 640 KEYSCAN64.BOOT m{$60}0@."{$60}h{$60}1++"*#$x-bd{$60}'0@4{$60}(l@0;(q(*<@-c{$60}{$60})0@>{$60}$&r,0{$60}z""@{$60}dr)+ m15e30t%.-c0b+$0l,0!#"#({$60}b2{$60}q,{$60}!@"#p{$60}gb{$60}t.3$u,jhuk#(u-b{$60}@.b"/ )("1#-3{$60}p{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60} {$60} END BEGIN 640 KEYSCAN64 m{$60},5,q,5,$,9,zl4@zo^es-{$60}iqlw0):d4a<vdtt;/kh<"l=&p$>;/a<x@).jq m\xv'{$60}jz&{$60}j7.28{$60}@'.je{$60}2d0\{$60}j@{$60}(3{$60}i0$)(-{$60}(i<#0!j4!*1^%{$60}2!9q4q^ mzjd{$60}c0#<k0'<s0'<t/c)__{$60}y(%c'd#d@6,8@6,>0,2"-qb"[qb#[qjf!a?6i mzx7vho\l>,<p+:uyq\g_t{$60}>mc0+p(:e{$60}a<nh;(\"j7^-{$60}-ri_z("g7g'ra#z m(+7&ho^i{$60}(uxqze{$60}a<nh3";k(.k%h@"]u<7p!b#2_^c0]6!+15e30t%.-c0@ m24y35$%,3$5$#0!xj0f@q8t4{$60}xp5{$60}zdgh,:-&{$60}.,&0-8h@*i_yuyq\h0^jd{$60} mc7c'8'bi,:#jc10#c!4#j4>@_ht8{$60}xp9{$60}ua@2(i(f$bi?xt-w:p-w3{$60}?({$60}+] mt{$60}-l{$60}h{$60}@o/8@x?_0#r{$60}5_2"c_2{$60}8y2#jq6p"h$qr_j+_h/^i_h7u3';&k0'< ms0'<t/b,{$60}-q)_yumqs@f]:7uc0#<z.{$60}(d.-@{$60}08'!x{$60}0({$60}0!{$60}0($(+7&h{$60}.^ m@<:];<<ya<;p%+f)q@v-{$60}hv-{$60}kf%qdg_/6w'g6w'b!#>8*d{$60}c8t"8*("j?^= m=<?*$/j@{$60}(3uh@"&r[umq_{$60}<i,m*d!)(ao:f]>{$60}#l{$60}:8g77'yo6f]fc(r0#0 myabervd(a<ohx{$60}b0tv"@{$60}+eyq\g_\"2b{$60}muuq_{$60}8ra#xf*j]>l>=><?hx{$60}*0 m]:g_c7o'c7c'r,{$60}#d-6@{$60}+euq\g_\":b{$60}muyq_{$60}:ra#x2*(!o7g'g7k'ra#w mj0"->,=hc7g'h{$60}/(p{$60}.0tv"i_xt{$60}w*t!w,t!w-#xr?^i?xt{$60}w&{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60} *{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60} {$60} END BEGIN 640 KEYSHOW m{$60}!-,"q,{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}*f3(-+_(#83h@{$60}@%q0@5a.b"b{$60}7%"!t$z(4(!<4(/03 mhax@%q0@3!1,$!-xh@"i_ht{$60}w*t!w,t!w-#x2?^={$60}q,x+@#<z.{$60}(d.i88'bb m!ze_c0#<k0'<s0'<t/a)_yt#$san{$60}-s*$.q88'bi{$60}(t"w*g_c0/<h{$60}>i?x4# mi0.-{$60}=rm{$60}-s-{$60}-s0^*+_c@'<2?^b!ph^{$60}q/*$/dx9@.($-vi_xt"w*d{$60}c0/< m6&!xj0"-{$60}mri_xt#w*{$60}'j7^%{$60}z4#c0'<k0#<s0#<t/bb_xx!w$g_h@<*/@,3 mra#y.&8#b!#=j?^-{$60}mri{$60}(t#w%a@>*({$60}j?z%{$60}z4#c0#<k0'<s0'<t/a)_yt# m$s@f{$60}^c@")#f6&"@!(8$a{$60}6b{$60}+t#$r{$60}v%!be!&dha020{$60}n8%z.{$60}(d.i@a0*@ 6!t8"j0!i,)$$b!#u8{$60}{$60}{$60}{$60}{$60}{$60}{$60}{$60}*({$60}8{$60}{$60}{$60} {$60} END