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************ Keyboard Input and housekeeping ************************
	 ;entered from &F00C

EEDA	LDX #&FF    ;
EEDC	LDA &EC     ;get value of most recently pressed key
EEDE	ORA &ED     ;Or it with previous key to check for presses
EEE0	BNE &EEE8   ;if A=0 no keys pressed so off you go
EEE2	LDA #&81    ;else enable keybd interupt only by writing bit 7
EEE4	STA &FE4E   ;and bit 0 of system VIA interupt register
EEE7	INX         ;set X=0
EEE8	STX &0242   ;reset keyboard semaphore


**********: Turn on Keyboard indicators *******************************
EEEB	PHP         ;save flags
EEEC	LDA &025A   ;read keyboard status;
			 ;Bit 7  =1 shift enabled
			 ;Bit 6  =1 control pressed
			 ;bit 5  =0 shift lock
			 ;Bit 4  =0 Caps lock
			 ;Bit 3  =1 shift pressed
EEEF	LSR         ;shift Caps bit into bit 3
EEF0	AND #&18    ;mask out all but 4 and 3
EEF2	ORA #&06    ;returns 6 if caps lock OFF &E if on
EEF4	STA &FE40   ;turn on or off caps light if required
EEF7	LSR         ;bring shift bit into bit 3
EEF8	ORA #&07    ;
EEFA	STA &FE40   ;turn on or off shift  lock light
EEFD	JSR &F12E   ;set keyboard counter
EF00	PLA         ;get back flags
EF01	RTS         ;return
			 ;


*************************************************************************
*                                                                       *
* MAIN KEYBOARD HANDLING ROUTINE   ENTRY FROM KEYV                      *
* ==========================================================            *
*                                                                       *
*                       ENTRY CONDITIONS                                *
*                       ================                                *
* C=0, V=0 Test Shift and CTRL keys.. exit with N set if CTRL pressed   *
*                                 ........with V set if Shift pressed   *
*                                                                       *
* C=1, V=0 Scan Keyboard as OSBYTE &79                                  *
*                                                                       *
* C=0, V=1 Key pressed interrupt entry                                  *
*                                                                       *
* C=1, V=1 Timer interrupt entry                                        *
*                                                                       *
*************************************************************************

EF02	BVC &EF0E   ;if V is clear then leave interrupt routine
EF04	LDA #&01    ;disable keyboard interrupts
EF06	STA &FE4E   ;by writing to VIA interrupt vector
EF09	BCS &EF13   ;if timer interrupt then EF13
EF0B	JMP &F00F   ;else to F00F

EF0E	BCC &EF16   ;if test SHFT & CTRL goto EF16
EF10	JMP &F0D1   ;else to F0D1
			 ;to scan keyboard
*************************************************************************
*       Timer interrupt entry                                           *
*************************************************************************

EF13	INC &0242   ;increment keyboard semaphore (to 0)


*************************************************************************
*       Test Shift and Control Keys entry                               *
*************************************************************************

EF16	LDA &025A   ;read keyboard status;
			 ;Bit 7  =1 shift enabled
			 ;Bit 6  =1 control pressed
			 ;bit 5  =0 shift lock
			 ;Bit 4  =0 Caps lock
			 ;Bit 3  =1 shift pressed
EF19	AND #&B7    ;zero bits 3 and 6
EF1B	LDX #&00    ;zero X to test for shift key press
EF1D	JSR &F02A   ;interrogate keyboard X=&80 if key determined by
			 ;X on entry is pressed
EF20	STX &FA     ;save X
EF22	CLV         ;clear V
EF23	BPL &EF2A   ;if no key press (X=0) then EF2A else
EF25	BIT &D9B7   ;set M and V
EF28	ORA #&08    ;set bit 3 to indicate Shift was pressed
EF2A	INX         ;check the control key
EF2B	JSR &F02A   ;via keyboard interrogate
EF2E	BCC &EEEB   ;if carry clear (entry via EF16) then off to EEEB
			 ;to turn on keyboard lights as required
EF30	BPL &EF34   ;if key not pressed goto EF30
EF32	ORA #&40    ;or set CTRL pressed bit in keyboard status byte in A
EF34	STA &025A   ;save status byte
EF37	LDX &EC     ;if no key previously pressed
EF39	BEQ &EF4D   ;then EF4D
EF3B	JSR &F02A   ;else check to see if key still pressed
EF3E	BMI &EF50   ;if so enter repeat routine at EF50
EF40	CPX &EC     ;else compare X with last key pressed (set flags)
EF42	STX &EC     ;store X in last key pressed
EF44	BNE &EF4D   ;if different from previous (Z clear) then EF4D
EF46	LDX #&00    ;else zero
EF48	STX &EC     ;last key pressed
EF4A	JSR &F01F   ;and reset repeat system
EF4D	JMP &EFE9   ;


********** REPEAT ACTION *************************************************
EF50	CPX &EC     ;if X<>than last key pressed
EF52	BNE &EF42   ;then back to EF42
EF54	LDA &E7     ;else get value of AUTO REPEAT COUNTDOWN TIMER
EF56	BEQ &EF7B   ;if 0 goto EF7B
EF58	DEC &E7     ;else decrement
EF5A	BNE &EF7B   ;and if not 0 goto EF7B
			 ;this means that either the repeat system is dormant
			 ;or it is not at the end of its count
EF5C	LDA &02CA   ;next value for countdown timer
EF5F	STA &E7     ;store it
EF61	LDA &0255   ;get auto repeat rate from 0255
EF64	STA &02CA   ;store it as next value for Countdown timer
EF67	LDA &025A   ;get keyboard status
EF6A	LDX &EC     ;get last key pressed
EF6C	CPX #&D0    ;if not SHIFT LOCK key (&D0) goto
EF6E	BNE &EF7E   ;EF7E
EF70	ORA #&90    ;sets shift enabled, & no caps lock all else preserved
EF72	EOR #&A0    ;reverses shift lock disables Caps lock and Shift enab
EF74	STA &025A   ;reset keyboard status
EF77	LDA #&00    ;and set timer
EF79	STA &E7     ;to 0
EF7B	JMP &EFE9   ;

EF7E	CPX #&C0    ;if not CAPS LOCK
EF80	BNE &EF91   ;goto EF91
EF82	ORA #&A0    ;sets shift enabled and disables SHIFT LOCK
EF84	BIT &FA     ;if bit 7 not set by (EF20) shift NOT pressed
EF86	BPL &EF8C   ;goto EF8C
EF88	ORA #&10    ;else set CAPS LOCK not enabled
EF8A	EOR #&80    ;reverse SHIFT enabled

EF8C	EOR #&90    ;reverse both SHIFT enabled and CAPs Lock
EF8E	JMP &EF74   ;reset keyboard status and set timer


*********** get ASCII code *********************************************
	 ;on entry X=key pressed internal number

EF91	LDA &EFAB,X ;get code from look up table
EF94	BNE &EF99   ;if not zero goto EF99 else TAB pressed
EF96	LDA &026B   ;get TAB character

EF99	LDX &025A   ;get keyboard status
EF9C	STX &FA     ;store it in &FA
EF9E	ROL &FA     ;rotate to get CTRL pressed into bit 7
EFA0	BPL &EFA9   ;if CTRL NOT pressed EFA9

EFA2	LDX &ED     ;get no. of previously pressed key
EFA4	BNE &EF4A   ;if not 0 goto EF4A to reset repeat system etc.
EFA6	JSR &EABF   ;else perform code changes for CTRL

EFA9	ROL &FA     ;move shift lock into bit 7
EFAB	BMI &EFB5   ;if not effective goto EFB5 else
EFAD	JSR &EA9C   ;make code changes for SHIFT

EFB0	ROL &FA     ;move CAPS LOCK into bit 7
EFB2	JMP &EFC1   ;and Jump to EFC1

EFB5	ROL &FA     ;move CAPS LOCK into bit 7
EFB7	BMI &EFC6   ;if not effective goto EFC6
EFB9	JSR &E4E3   ;else make changes for CAPS LOCK on, return with
			 ;C clear for Alphabetic codes
EFBC	BCS &EFC6   ;if carry set goto EFC6 else make changes for
EFBE	JSR &EA9C   ;SHIFT as above

EFC1	LDX &025A   ;if shift enabled bit is clear
EFC4	BPL &EFD1   ;goto EFD1
EFC6	ROL &FA     ;else get shift bit into 7
EFC8	BPL &EFD1   ;if not set goto EFD1
EFC8	BPL &EFD1   ;if not set goto EFD1
EFCA	LDX &ED     ;get previous key press
EFCC	BNE &EFA4   ;if not 0 reset repeat system etc. via EFA4
EFCE	JSR &EA9C   ;else make code changes for SHIFT
EFD1	CMP &026C   ;if A<> ESCAPE code
EFD4	BNE &EFDD   ;goto EFDD
EFD6	LDX &0275   ;get Escape key status
EFD9	BNE &EFDD   ;if ESCAPE returns ASCII code goto EFDD
EFDB	STX &E7     ;store in Auto repeat countdown timer

EFDD	TAY         ;
EFDE	JSR &F129   ;disable keyboard
EFE1	LDA &0259   ;read Keyboard disable flag used by Econet
EFE4	BNE &EFE9   ;if keyboard locked goto EFE9
EFE6	JSR &E4F1   ;put character in input buffer
EFE9	LDX &ED     ;get previous keypress
EFEB	BEQ &EFF8   ;if none  EFF8
EFED	JSR &F02A   ;examine to see if key still pressed
EFF0	STX &ED     ;store result
EFF2	BMI &EFF8   ;if pressed goto EFF8
EFF4	LDX #&00    ;else zero X
EFF6	STX &ED     ;and &ED

EFF8	LDX &ED     ;get &ED
EFFA	BNE &F012   ;if not 0 goto F012
EFFC	LDY #&EC    ;get first keypress into Y
EFFE	JSR &F0CC   ;scan keyboard from &10 (osbyte 122)

F001	BMI &F00C   ;if exit is negative goto F00C
F003	LDA &EC     ;else make last key the
F005	STA &ED     ;first key pressed i.e. rollover

F007	STX &EC     ;save X into &EC
F009	JSR &F01F   ;set keyboard repeat delay
F00C	JMP &EEDA   ;go back to EEDA


*************************************************************************
*   Key pressed interrupt entry point                                   *
*************************************************************************
			 ;enters with X=key
F00F	JSR &F02A   ;check if key pressed

F012	LDA &EC     ;get previous key press
F014	BNE &F00C   ;if none back to housekeeping routine
F016	LDY #&ED    ;get last keypress into Y
F018	JSR &F0CC   ;and scan keyboard
F01B	BMI &F00C   ;if negative on exit back to housekeeping
F01D	BPL &F007   ;else back to store X and reset keyboard delay etc.


**************** Set Autorepeat countdown timer **************************

F01F	LDX #&01    ;set timer to 1
F021	STX &E7     ;
F023	LDX &0254   ;get next timer value
F026	STX &02CA   ;and store it
F029	RTS         ;


*************** Interrogate Keyboard routine ***********************
			 ;
F02A	LDY #&03    ;stop Auto scan
F02C	STY &FE40   ;by writing to system VIA
F02F	LDY #&7F    ;set bits 0 to 6 of port A to input on bit 7
			 ;output on bits 0 to 6
F031	STY &FE43   ;
F034	STX &FE4F   ;write X to Port A system VIA
F037	LDX &FE4F   ;read back &80 if key pressed (M set)
F03A	RTS         ;and return


*************************************************************************
*                                                                       *
*       KEY TRANSLATION TABLES                                          *
*                                                                       *
*       7 BLOCKS interspersed with unrelated code                       *
*************************************************************************

*key data block 1

F03B	DB  71,33,34,35,84,38,87,2D,5E,8C
	 ;       q ,3 ,4 ,5 ,f4,8 ,f7,- ,^ ,rt



*************************************************************************
*                                                                       *
*       OSBYTE 120  Write KEY pressed Data                              *
*                                                                       *
*************************************************************************


F045	STY &EC     ;store Y as latest key pressed
F047	STX &ED     ;store X as previous key pressed
F049	RTS         ;and exit

*key data block 2

F04A	DB  80,77,65,74,37,69,39,30,5F,8E
	 ;       f0,w ,e ,t ,7 ,i ,9 ,0 ,_ ,lft

F055	JMP (&FDFE) ;Jim paged entry vector
F058	JMP (&FA)   ;

*key data block 3

F05A	DB  31,32,64,72,36,75,6F,70,5B,8F
	 ;       1 ,2 ,d ,r ,6 ,u ,o ,p ,[ ,dn


*************************************************************************
*                                                                       *
* Main entry to keyboard routines                                       *
*                                                                       *
*************************************************************************

F065	BIT &D9B7   ;set V and M
F068	JMP (&0228) ;i.e. KEYV

*key data block 4

F06B	DB  01,61,78,66,79,6A,6B,40,3A,0D
	 ;       CL,a ,x ,f ,y ,j ,k ,@ ,: ,RETN  N.B CL=CAPS LOCK

*speech routine data
F075	DB  00,FF,01,02,09,0A

*key data block 5

F07B	DB  02,73,63,67,68,6E,6C,3B,5D,7F
	 ;       SL,s ,c ,g ,h ,n ,l ,; ,] ,DEL N.B. SL=SHIFT LOCK



*************************************************************************
*                                                                       *
*       OSBYTE 131  READ OSHWM  (PAGE in BASIC)                         *
*                                                                       *
*************************************************************************


F085	LDY &0244 ;read current OSHWM
F088	LDX #&00    ;
F08A	RTS         ;

*key data block 6

F08B	DB          00 ,7A,20   ,76,62,6D,2C,2E,2F,8B
	 ;               TAB,Z ,SPACE,V ,b ,m ,, ,. ,/ ,copy

***** set input buffer number and flush it *****************************

F095	LDX &0241   ;get current input buffer
F098	JMP &E1AD   ;flush it

*key data block 7

F09B	DB  1B,81,82,83,85,86,88,89,5C,8D
	 ;      ESC,f1,f2,f3,f5,f6,f8,f9,\ ,


F0A5	JMP (&0220) ;goto eventV handling routine




*************************************************************************
*                                                                       *
*       OSBYTE 15  FLUSH SELECTED BUFFER CLASS                          *
*                                                                       *
*************************************************************************

			 ;flush selected buffer
			 ;X=0 flush all buffers
			 ;X>1 flush input buffer

F0A8	BNE &F095   ;if X<>1 flush input buffer only
F0AA	LDX #&08    ;else load highest buffer number (8)
F0AC	CLI         ;allow interrupts
F0AD	SEI         ;briefly!
F0AE	JSR &F0B4   ;flush buffer
F0B1	DEX         ;decrement X to point at next buffer
F0B2	BPL &F0AC   ;if X>=0 flush next buffer
			 ;at this point X=255


*************************************************************************
*                                                                       *
*       OSBYTE 21  FLUSH SPECIFIC BUFFER                                *
*                                                                       *
*************************************************************************
;on entry X=buffer number

F0B4	CPX #&09    ;is X<9?
F0B6	BCC &F098   ;if so flush buffer or else
F0B8	RTS         ;exit
			 ;
*************************************************************************
*                                                                       *
*               Issue *HELP to ROMS                                     *
*                                                                       *
*************************************************************************
F0B9	LDX #&09    ;
F0BB	JSR &F168   ;
F0BE	JSR &FA4A   ;print following message routine return after BRK
F0C1	DB  &0D     ;carriage return
F0C2	DS  'OS 1.20' ;help message
F0C9	DB  &0D     ;carriage return
F0CA	BRK         ;
F0CB	RTS         ;


*************************************************************************
*                                                                       *
*       OSBYTE 122  KEYBOARD SCAN FROM &10 (16)                         *
*                                                                       *
*************************************************************************

    	            ;
F0CC	CLC         ;clear carry
F0CD	LDX #&10    ;set X to 10
    	            ;


*************************************************************************
*                                                                       *
*       OSBYTE 121  KEYBOARD SCAN FROM VALUE IN X                       *
*                                                                       *
*************************************************************************

F0CF	BCS &F068   ;if carry set (by osbyte 121) F068
    	            ;Jmps via KEYV and hence back to;


*************************************************************************
*        Scan Keyboard C=1, V=0 entry via KEYV                          *
*************************************************************************

F0D1	TXA         ;if X is +ve goto F0D9
F0D2	BPL &F0D9   ;
F0D4	JSR &F02A   ;else interrogate keyboard
F0D7	BCS &F12E   ;if carry set F12E to set Auto scan else
F0D9	PHP         ;push flags
F0DA	BCC &F0DE   ;if carry clear goto FODE else
F0DC	LDY #&EE    ;set Y so next operation saves to 2cd
F0DE	STA &01DF,Y ;can be 2cb,2cc or 2cd
F0E1	LDX #&09    ;set X to 9
F0E3	JSR &F129   ;select auto scan
F0E6	LDA #&7F    ;set port A for input on bit 7 others outputs
F0E8	STA &FE43   ;
F0EB	LDA #&03    ;stop auto scan
F0ED	STA &FE40   ;
F0F0	LDA #&0F    ;select non-existent keyboard column F (0-9 only!)
F0F2	STA &FE4F   ;
F0F5	LDA #&01    ;cancel keyboard interrupt
F0F7	STA &FE4D   ;
F0FA	STX &FE4F   ;select column X (9 max)
F0FD	BIT &FE4D   ;if bit 1 =0 there is no keyboard interrupt so
F100	BEQ &F123   ;goto F123
F102	TXA         ;else put column address in A

F103	CMP &01DF,Y ;compare with 1DF+Y
F106	BCC &F11E   ;if less then F11E
F108	STA &FE4F   ;else select column again
F10B	BIT &FE4F   ;and if bit 7 is 0
F10E	BPL &F11E   ;then F11E
F110	PLP         ;else push and pull flags
F111	PHP         ;
F112	BCS &F127   ;and if carry set goto F127
F114	PHA         ;else Push A
F115	EOR &0000,Y ;EOR with EC,ED, or EE depending on Y value
F118	ASL         ;shift left  
F119	CMP #&01    ;set carry if = or greater than number holds EC,ED,EE
F11B	PLA         ;get back A
F11C	BCS &F127   ;if carry set F127
F11E	CLC         ;else clear carry
F11F	ADC #&10    ;add 16
F121	BPL &F103   ;and do it again if 0=<result<128
F123	DEX         ;decrement X
F124	BPL &F0E3   ;scan again if greater than 0
F126	TXA         ;
F127	TAX         ;
F128	PLP         ;pull flags

F129	JSR &F12E   ;call autoscan
F12C	CLI         ;allow interrupts 
F12D	SEI         ;disable interrupts



*************Enable counter scan of keyboard columns *******************
    	            ;called from &EEFD, &F129

F12E	LDA #&0B    ;select auto scan of keyboard
F130	STA &FE40   ;tell VIA
F133	TXA         ;Get A into X
F134	RTS         ;and return


\ No newline at end of file