;; MASK-INT
L0038 PUSH AF ; save the registers.
PUSH HL ; but not IY unfortunately.
LD HL,(0x5C78) ; fetch two bytes at FRAMES1.
INC HL ; increment lowest two bytes of counter.
LD (0x5C78),HL ; place back in FRAMES1.
LD A,H ; test if the result
OR L ; was zero.
JR NZ,L0048 ; forward to KEY-INT if not.
INC (IY+0x40) ; otherwise increment FRAMES3 the third byte.
; now save the rest of the main registers and read and decode the keyboard.
;; KEY-INT
L0048 PUSH BC ; save the other
PUSH DE ; main registers.
CALL L02BF ; routine KEYBOARD executes a stage
; in the process of reading a key-press.
POP DE ;
POP BC ; restore registers.
POP HL ;
POP AF ;
EI ; enable interrupts.
RET ; return.
;-----------
; Key tables
;-----------
; These six look-up tables are used by the keyboard reading routine
; to decode the key values.
; The first table contains the maps for the 39 keys of the standard
; 40-key Spectrum keyboard. The remaining key [SHIFT $27] is read directly.
; The key values 0-38 map to their ascii upper-case characters except for
; symbol-shift $0E.
;; MAIN-KEYS
L0205 DEFB $42 ; B
DEFB $48 ; H
DEFB $59 ; Y
DEFB $36 ; 6
DEFB $35 ; 5
DEFB $54 ; T
DEFB $47 ; G
DEFB $56 ; V
DEFB $4E ; N
DEFB $4A ; J
DEFB $55 ; U
DEFB $37 ; 7
DEFB $34 ; 4
DEFB $52 ; R
DEFB $46 ; F
DEFB $43 ; C
DEFB $4D ; M
DEFB $4B ; K
DEFB $49 ; I
DEFB $38 ; 8
DEFB $33 ; 3
DEFB $45 ; E
DEFB $44 ; D
DEFB $58 ; X
DEFB $0E ; SYMBOL SHIFT
DEFB $4C ; L
DEFB $4F ; O
DEFB $39 ; 9
DEFB $32 ; 2
DEFB $57 ; W
DEFB $53 ; S
DEFB $5A ; Z
DEFB $20 ; SPACE
DEFB $0D ; ENTER
DEFB $50 ; P
DEFB $30 ; 0
DEFB $31 ; 1
DEFB $51 ; Q
DEFB $41 ; A
;; E-UNSHIFT
L022C DEFB $E3 ; READ
DEFB $C4 ; BIN
DEFB $E0 ; LPRINT
DEFB $E4 ; DATA
DEFB $B4 ; TAN
DEFB $BC ; SGN
DEFB $BD ; ABS
DEFB $BB ; SQR
DEFB $AF ; CODE
DEFB $B0 ; VAL
DEFB $B1 ; LEN
DEFB $C0 ; USR
DEFB $A7 ; PI
DEFB $A6 ; INKEY$
DEFB $BE ; PEEK
DEFB $AD ; TAB
DEFB $B2 ; SIN
DEFB $BA ; INT
DEFB $E5 ; RESTORE
DEFB $A5 ; RND
DEFB $C2 ; CHR$
DEFB $E1 ; LLIST
DEFB $B3 ; COS
DEFB $B9 ; EXP
DEFB $C1 ; STR$
DEFB $B8 ; LN
;; EXT-SHIFT
L0246 DEFB $7E ; ~
DEFB $DC ; BRIGHT
DEFB $DA ; PAPER
DEFB $5C ; \
DEFB $B7 ; ATN
DEFB $7B ; {
DEFB $7D ; }
DEFB $D8 ; CIRCLE
DEFB $BF ; IN
DEFB $AE ; VAL$
DEFB $AA ; SCREEN$
DEFB $AB ; ATTR
DEFB $DD ; INVERSE
DEFB $DE ; OVER
DEFB $DF ; OUT
DEFB $7F ; (Copyright character)
DEFB $B5 ; ASN
DEFB $D6 ; VERIFY
DEFB $7C ; |
DEFB $D5 ; MERGE
DEFB $5D ; ]
DEFB $DB ; FLASH
DEFB $B6 ; ACS
DEFB $D9 ; INK
DEFB $5B ; [
DEFB $D7 ; BEEP
;; CTL-CODES
L0260 DEFB $0C ; DELETE
DEFB $07 ; EDIT
DEFB $06 ; CAPS LOCK
DEFB $04 ; TRUE VIDEO
DEFB $05 ; INVERSE VIDEO
DEFB $08 ; CURSOR LEFT
DEFB $0A ; CURSOR DOWN
DEFB $0B ; CURSOR UP
DEFB $09 ; CURSOR RIGHT
DEFB $0F ; GRAPHICS
;; SYM-CODES
L026A DEFB $E2 ; STOP
DEFB $2A ; *
DEFB $3F ; ?
DEFB $CD ; STEP
DEFB $C8 ; >=
DEFB $CC ; TO
DEFB $CB ; THEN
DEFB $5E ; ^
DEFB $AC ; AT
DEFB $2D ; -
DEFB $2B ; +
DEFB $3D ; =
DEFB $2E ; .
DEFB $2C ; ,
DEFB $3B ; ;
DEFB $22 ; "
DEFB $C7 ; <=
DEFB $3C ; <
DEFB $C3 ; NOT
DEFB $3E ; >
DEFB $C5 ; OR
DEFB $2F ; /
DEFB $C9 ; <>
DEFB $60 ; pound
DEFB $C6 ; AND
DEFB $3A ; :
;; E-DIGITS
L0284 DEFB $D0 ; FORMAT
DEFB $CE ; DEF FN
DEFB $A8 ; FN
DEFB $CA ; LINE
DEFB $D3 ; OPEN#
DEFB $D4 ; CLOSE#
DEFB $D1 ; MOVE
DEFB $D2 ; ERASE
DEFB $A9 ; POINT
DEFB $CF ; CAT
;*******************************
;** Part 2. KEYBOARD ROUTINES **
;*******************************
; Using shift keys and a combination of modes the Spectrum 40-key keyboard
; can be mapped to 256 input characters
;----------------------------------------------------------------------------
;
; 0 1 2 3 4 -Bits- 4 3 2 1 0
; PORT PORT
;
; F7FE [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ] | [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 0 ] EFFE
; ^ | v
; FBFE [ Q ] [ W ] [ E ] [ R ] [ T ] | [ Y ] [ U ] [ I ] [ O ] [ P ] DFFE
; ^ | v
; FDFE [ A ] [ S ] [ D ] [ F ] [ G ] | [ H ] [ J ] [ K ] [ L ] [ ENT ] BFFE
; ^ | v
; FEFE [SHI] [ Z ] [ X ] [ C ] [ V ] | [ B ] [ N ] [ M ] [sym] [ SPC ] 7FFE
; ^ $27 $18 v
; Start End
; 00100111 00011000
;
;----------------------------------------------------------------------------
; The above map may help in reading.
; The neat arrangement of ports means that the B register need only be
; rotated left to work up the left hand side and then down the right
; hand side of the keyboard. When the reset bit drops into the carry
; then all 8 half-rows have been read. Shift is the first key to be
; read. The lower six bits of the shifts are unambiguous.
;------------------
; Keyboard scanning
;------------------
; from keyboard and s-inkey$
; returns 1 or 2 keys in DE, most significant shift first if any
; key values 0-39 else 255
;; KEY-SCAN
L028E LD L,$2F ; initial key value
; valid values are obtained by subtracting
; eight five times.
LD DE,$FFFF ; a buffer for 2 keys.
ld ix,keymatrix+7
LD BC,$FEFE ; the commencing port address
; B holds 11111110 initially and is also
; used to count the 8 half-rows
;; KEY-LINE
L0296 ;IN A,(C) ; read the port to A - bits will be reset
; if a key is pressed else set.
ld a,(ix)
dec ix
CPL ; complement - pressed key-bits are now set
AND $1F ; apply 00011111 mask to pick up the
; relevant set bits.
JR Z,L02AB ; forward to KEY-DONE if zero and therefore
; no keys pressed in row at all.
LD H,A ; transfer row bits to H
LD A,L ; load the initial key value to A
;; KEY-3KEYS
L029F INC D ; now test the key buffer
RET NZ ; if we have collected 2 keys already
; then too many so quit.
;; KEY-BITS
L02A1 SUB $08 ; subtract 8 from the key value
; cycling through key values (top = $27)
; e.g. 2F> 27>1F>17>0F>07
; 2E> 26>1E>16>0E>06
SRL H ; shift key bits right into carry.
JR NC,L02A1 ; back to KEY-BITS if not pressed
; but if pressed we have a value (0-39d)
LD D,E ; transfer a possible previous key to D
LD E,A ; transfer the new key to E
JR NZ,L029F ; back to KEY-3KEYS if there were more
; set bits - H was not yet zero.
;; KEY-DONE
L02AB DEC L ; cycles 2F>2E>2D>2C>2B>2A>29>28 for
; each half-row.
RLC B ; form next port address e.g. FEFE > FDFE
JR C,L0296 ; back to KEY-LINE if still more rows to do.
LD A,D ; now test if D is still FF ?
INC A ; if it is zero we have at most 1 key
; range now $01-$28 (1-40d)
RET Z ; return if one key or no key.
CP $28 ; is it capsshift (was $27) ?
RET Z ; return if so.
CP $19 ; is it symbol shift (was $18) ?
RET Z ; return also
LD A,E ; now test E
LD E,D ; but first switch
LD D,A ; the two keys.
CP $18 ; is it symbol shift ?
RET ; return (with zero set if it was).
; but with symbol shift now in D
;-------------------------------
; Scan keyboard and decode value
;-------------------------------
; from interrupt 50 times a second
;
;; KEYBOARD
L02BF CALL L028E ; routine KEY-SCAN
RET NZ ; return if invalid combinations
; then decrease the counters within the two key-state maps
; as this could cause one to become free.
; if the keyboard has not been pressed during the last five interrupts
; then both sets will be free.
LD HL,$5C00 ; point to KSTATE-0
;; K-ST-LOOP
L02C6 BIT 7,(HL) ; is it free ? ($FF)
JR NZ,L02D1 ; forward to K-CH-SET if so
INC HL ; address 5-counter
DEC (HL) ; decrease counter
DEC HL ; step back
JR NZ,L02D1 ; forward to K-CH-SET if not at end of count
LD (HL),$FF ; else mark it free.
;; K-CH-SET
L02D1 LD A,L ; store low address byte.
LD HL,$5C04 ; point to KSTATE-4
; (ld l, $04)
CP L ; have 2 been done ?
JR NZ,L02C6 ; back to K-ST-LOOP to consider this 2nd set
; now the raw key (0-38) is converted to a main key (uppercase).
CALL L031E ; routine K-TEST to get main key in A
RET NC ; return if single shift
LD HL,$5C00 ; point to KSTATE-0
CP (HL) ; does it match ?
JR Z,L0310 ; forward to K-REPEAT if so
; if not consider the second key map.
EX DE,HL ; save kstate-0 in de
LD HL,$5C04 ; point to KSTATE-4
CP (HL) ; does it match ?
JR Z,L0310 ; forward to K-REPEAT if so
; having excluded a repeating key we can now consider a new key.
; the second set is always examined before the first.
BIT 7,(HL) ; is it free ?
JR NZ,L02F1 ; forward to K-NEW if so.
EX DE,HL ; bring back kstate-0
BIT 7,(HL) ; is it free ?
RET Z ; return if not.
; as we have a key but nowhere to put it yet.
; continue or jump to here if one of the buffers was free.
;; K-NEW
L02F1 LD E,A ; store key in E
LD (HL),A ; place in free location
INC HL ; advance to interrupt counter
LD (HL),$05 ; and initialize to 5
INC HL ; advance to delay
LD A,($5C09) ; pick up system variable REPDEL
LD (HL),A ; and insert that for first repeat delay.
INC HL ; advance to last location of state map.
LD C,(IY+$07) ; pick up MODE (3 bytes)
LD D,(IY+$01) ; pick up FLAGS (3 bytes)
PUSH HL ; save state map location
; Note. could now have used.
; ld l,$41; ld c,(hl); ld l,$3B; ld d,(hl).
; six and two threes of course.
CALL L0333 ; routine K-DECODE
POP HL ; restore map pointer
LD (HL),A ; put decoded key in last location of map.
;; K-END
L0308 LD ($5C08),A ; update LASTK system variable.
SET 5,(IY+$01) ; FLAGS - signal new key.
RET ; done
;-------------------
; Repeat key routine
;-------------------
; A possible repeat has been identified. HL addresses the raw (main) key.
; The last location holds the decoded key (from the first context).
;; K-REPEAT
L0310 INC HL ; advance
LD (HL),$05 ; maintain interrupt counter at 5
INC HL ; advance
DEC (HL) ; decrease REPDEL value.
RET NZ ; return if not yet zero.
LD A,($5C0A) ; REPPER
LD (HL),A ; but for subsequent repeats REPPER will be used.
INC HL ; advance
;
LD A,(HL) ; pick up the key decoded possibly in another
; context.
JR L0308 ; back to K-END
;---------------
; Test key value
;---------------
; also called from s-inkey$
; begin by testing for a shift with no other.
;; K-TEST
L031E LD B,D ; load most significant key to B
; will be $FF if not shift.
LD D,$00 ; and reset D to index into main table
LD A,E ; load least significant key from E
CP $27 ; is it higher than 39d i.e. FF
RET NC ; return with just a shift (in B now)
CP $18 ; is it symbol shift ?
JR NZ,L032C ; forward to K-MAIN if not
; but we could have just symbol shift and no other
BIT 7,B ; is other key $FF (ie not shift)
RET NZ ; return with solitary symbol shift
;; K-MAIN
L032C LD HL,L0205 ; address: MAIN-KEYS
ADD HL,DE ; add offset 0-38
LD A,(HL) ; pick up main key value
SCF ; set carry flag
RET ; return (B has other key still)
;------------------
; Keyboard decoding
;------------------
; also called from s-inkey$
;; K-DECODE
L0333 LD A,E ; pick up the stored main key
CP $3A ; an arbitrary point between digits and letters
JR C,L0367 ; forward to K-DIGIT with digits,space,enter
DEC C ; decrease MODE ( 0='KLC', 1='E', 2='G')
JP M,L034F ; to K-KLC-LET if was zero
JR Z,L0341 ; to K-E-LET if was 1 for extended letters.
; proceed with graphic codes.
; Note. should selectively drop return address if code > 'U' ($55).
; i.e. abort the KEYBOARD call.
; e.g. cp 'V'; jr c addit; pop af; ;;addit etc. (5 bytes of instruction).
; (s-inkey$ never gets into graphics mode.)
;; addit
ADD A,$4F ; add offset to augment 'A' to graphics A say.
RET ; return.
; Note. ( but [GRAPH] V gives RND, etc ).
; the jump was to here with extended mode with uppercase A-Z.
;; K-E-LET
L0341 LD HL,L022C-$41 ; base address of E-UNSHIFT L022c
; ( $01EB in standard ROM )
INC B ; test B is it empty i.e. not a shift
JR Z,L034A ; forward to K-LOOK-UP if neither shift
LD HL,L0246-$41 ; Address: $0205 L0246-$41 EXT-SHIFT base
;; K-LOOK-UP
L034A LD D,$00 ; prepare to index
ADD HL,DE ; add the main key value
LD A,(HL) ; pick up other mode value
RET ; return
; the jump was here with mode = 0
;; K-KLC-LET
L034F LD HL,L026A-$41 ; base of sym-codes
BIT 0,B ; shift=$27 sym-shift=$18
JR Z,L034A ; back to K-LOOK-UP with symbol-shift
BIT 3,D ; test FLAGS is it 'K' mode (from OUT-CURS)
JR Z,L0364 ; skip to K-TOKENS if so
BIT 3,(IY+$30) ; test FLAGS2 - consider CAPS LOCK ?
RET NZ ; return if so with main code.
INC B ; is shift being pressed ?
; result zero if not
RET NZ ; return if shift pressed.
ADD A,$20 ; else convert the code to lower case.
RET ; return.
; the jump was here for tokens
;; K-TOKENS
L0364 ADD A,$A5 ; add offset to main code so that 'A'
; becomes 'NEW' etc.
RET ; return
; the jump was here with digits, space, enter and symbol shift (< $xx)
;; K-DIGIT
L0367 CP $30 ; is it '0' or higher ?
RET C ; return with space, enter and symbol-shift
DEC C ; test MODE (was 0='KLC', 1='E', 2='G')
JP M,L039D ; jump to K-KLC-DGT if was 0.
JR NZ,L0389 ; forward to K-GRA-DGT if mode was 2.
; continue with extended digits 0-9.
LD HL,L0284-$30 ; $0254 - base of E-DIGITS
BIT 5,B ; test - shift=$27 sym-shift=$18
JR Z,L034A ; to K-LOOK-UP if sym-shift
CP $38 ; is character '8' ?
JR NC,L0382 ; to K-8-&-9 if greater than '7'
SUB $20 ; reduce to ink range $10-$17
INC B ; shift ?
RET Z ; return if not.
ADD A,$08 ; add 8 to give paper range $18 - $1F
RET ; return
; 89
;; K-8-&-9
L0382 SUB $36 ; reduce to 02 and 03 bright codes
INC B ; test if shift pressed.
RET Z ; return if not.
ADD A,$FE ; subtract 2 setting carry
RET ; to give 0 and 1 flash codes.
; graphics mode with digits
;; K-GRA-DGT
L0389 LD HL,L0260-$30 ; $0230 base address of CTL-CODES
CP $39 ; '9' ?
JR Z,L034A ; to K-LOOK-UP changed to $0F
CP $30 ; '0' ?
JR Z,L034A ; to K-LOOK-UP changed to $0C
; for keys '0' - '7' we assign a mosaic character depending on shift.
AND $07 ; convert character to number. 0 - 7.
ADD A,$80 ; add offset - they start at $80
INC B ; destructively test for shift
RET Z ; and return if not pressed.
XOR $0F ; toggle bits becomes range $88-$8F
RET ; return.
; now digits in 'KLC' mode
;; K-KLC-DGT
L039D INC B ; return with digit codes if neither
RET Z ; shift pressed.
BIT 5,B ; test for caps shift
LD HL,L0260-$30 ; base of table CTL-CODES
JR NZ,L034A ; back to K-LOOK-UP
; must have been symbol shift
SUB $10 ; for ascii most will now be correct
; on a standard typewriter.
CP $22 ; but '@' is not - see below.
JR Z,L03B2 ; forward to to K-@-CHAR if so
CP $20 ; '_' is the other one that fails
RET NZ ; return if not.
LD A,$5F ; substitute ascii '_'
RET ; return.
;; K-@-CHAR
L03B2 LD A,$40 ; substitute ascii '@'
RET ; return.