OS SERIES VII
GEOFF COX

*************************************************************************
*                                                                       *
*       OSBYTE  9   Duration of first colour                            *
*                                                                       *
*************************************************************************
;on entry Y=0, X=new value

E6B0	INY         ;Y is incremented to 1
E6B1	CLC         ;clear carry


*************************************************************************
*                                                                       *
*       OSBYTE  10   Duration of second colour                          *
*                                                                       *
*************************************************************************

;on entry Y=0 or 1 if from FX 9 call, X=new value

E6B2	LDA &0252,Y ;get mark period count
E6B5	PHA         ;push it
E6B6	TXA         ;get new count
E6B7	STA &0252,Y ;store it
E6BA	PLA         ;get back original value
E6BB	TAY         ;put it in Y
E6BC	LDA &0251   ;get value of flash counter
E6BF	BNE &E6D1   ;if not zero E6D1

E6C1	STX &0251   ;else restore old value
E6C4	LDA &0248   ;get current video ULA control register setting
E6C7	PHP         ;push flags
E6C8	ROR         ;rotate bit 0 into carry, carry into bit 7
E6C9	PLP         ;get back flags
E6CA	ROL         ;rotate back carry into bit 0
E6CB	STA &0248   ;store it in RAM copy
E6CE	STA &FE20   ;and ULA control register

E6D1	BVC &E6AD   ;then exit via OSBYTE 7/8


*************************************************************************
*                                                                       *
*       OSBYTE  2   select input stream                                 *
*                                                                       *
*************************************************************************

;on input X contains stream number

E6D3	TXA         ;A=X
E6D4	AND #&01    ;blank out bits 1 - 7
E6D6	PHA         ;push A
E6D7	LDA &0250   ;and get current ACIA control setting
E6DA	ROL         ;Bit 7 into carry
E6DB	CPX #&01    ;if X>=1 then
E6DD	ROR         ;bit 7 of A=1
E6DE	CMP &0250   ;compare this with ACIA control setting
E6E1	PHP         ;push processor
E6E2	STA &0250   ;put A into ACIA control setting
E6E5	STA &FE08   ;and write to control register
E6E8	JSR &E173   ;set up RS423 buffer
E6EB	PLP         ;get back P
E6EC	BEQ &E6F1   ;if new setting different from old E6F1 else
E6EE	BIT &FE09   ;set bit 6 and 7

E6F1	LDX &0241   ;get current input buffer number
E6F4	PLA         ;get back A
E6F5	STA &0241   ;store it
E6F8	RTS         ;and return
    	


*************************************************************************
*                                                                       *
*       OSBYTE  13   disable events                                     *
*                                                                       *
*************************************************************************

    	;X contains event number 0-9

E6F9	TYA         ;Y=0 A=0



*************************************************************************
*                                                                       *
*       OSBYTE  14   enable events                                      *
*                                                                       *
*************************************************************************

    	;X contains event number 0-9


E6FA	CPX #&0A    ;if X>9
E6FC	BCS &E6AE   ;goto E6AE for exit
E6FE	LDY &02BF,X ;else get event enable flag
E701	STA &02BF,X ;store new value in flag
E704	BVC &E6AD   ;and exit via E6AD



*************************************************************************
*                                                                       *
*       OSBYTE  16   Select A/D channel                                 *
*                                                                       *
*************************************************************************
 ;X contains channel number or 0 if disable conversion

E706	BEQ &E70B   ;if X=0 then E70B
E708	JSR &DE8C   ;start conversion

E70B	LDA &024D   ;get  current maximum ADC channel number
E70E	STX &024D   ;store new value
E711	TAX         ;put old value in X
E712	RTS         ;and exit
    	            ;


*************************************************************************
*                                                                       *
*       OSBYTE 129   Read key within time limit                         *
*                                                                       *
*************************************************************************
 ;X and Y contains either time limit in centi seconds Y=&7F max
 ; or Y=&FF and X=-ve INKEY value

E713	TYA         ;A=Y
E714	BMI &E721   ;if Y=&FF the E721
E716	CLI         ;else allow interrupts
E717	JSR &DEBB   ;and go to timed routine
E71A	BCS &E71F   ;if carry set then E71F
E71C	TAX         ;then X=A
E71D	LDA #&00    ;A=0

E71F	TAY         ;Y=A
E720	RTS         ;and return
    	            ;
    	            ;scan keyboard
E721	TXA         ;A=X
E722	EOR #&7F    ;convert to keyboard input
E724	TAX         ;X=A
E725	JSR &F068   ;then scan keyboard
E728	ROL         ;put bit 7 into carry
E729	LDX #&FF    ;X=&FF
E72B	LDY #&FF    ;Y=&FF
E72D	BCS &E731   ;if bit 7 of A was set goto E731 (RTS)
E72F	INX         ;else X=0
E730	INY         ;and Y=0
E731	RTS         ;and exit


********** check occupancy of input or free space of output buffer *******
    	            ;X=buffer number
    	;Buffer number  Address         Flag    Out pointer     In pointer
    	;0=Keyboard     3E0-3FF         2CF     2D8             2E1
    	;1=RS423 Input  A00-AFF         2D0     2D9             2E2
    	;2=RS423 output 900-9BF         2D1     2DA             2E3
    	;3=printer      880-8BF         2D2     2DB             2E4
    	;4=sound0       840-84F         2D3     2DC             2E5
    	;5=sound1       850-85F         2D4     2DD             2E6
    	;6=sound2       860-86F         2D5     2DE             2E7
    	;7=sound3       870-87F         2D6     2DF             2E8
    	;8=speech       8C0-8FF         2D7     2E0             2E9

E732	TXA         ;buffer number in A
E733	EOR #&FF    ;invert it
E735	TAX         ;X=A
E736	CPX #&02    ;is X>1
E738	CLV         ;clear V flag
E739	BVC &E73E   ;and goto E73E count buffer

E73B	BIT &D9B7   ;set V
E73E	JMP (&022E) ;CNPV defaults to E1D1


************* check RS423 input buffer ************************************

E741	SEC
E742	LDX #&01    ;X=1 to point to buffer
E744	JSR &E738   ;and count it
E747	CPY #&01    ;if the hi byte of the answer is 1 or more
E749	BCS &E74E   ;then Return
E74B	CPX &025B   ;else compare with minimum buffer space
E74E	RTS         ;and exit


*************************************************************************
*                                                                       *
*       OSBYTE 128  READ ADC CHANNEL                                    *
*                                                                       *
*************************************************************************

;ON Entry: X=0             Exit Y contains number of last channel converted
;   	   X=channel number       X,Y contain 16 bit value read from channe
;   	   X<0 Y=&FF              X returns information about various buffers
;   	   X=&FF (keyboard )      X=number of characters in buffer
;   	   X=&FE (RS423 Input)    X=number of characters in buffer
;   	   X=&FD (RS423 output)   X=number of empty spaces in buffer
;   	   X=&FC (Printer)        X=number of empty spaces in buffer
;   	   X=&FB (sound 0)        X=number of empty spaces in buffer
;   	   X=&FA (sound 1)        X=number of empty spaces in buffer
;   	   X=&F9 (sound 2)        X=number of empty spaces in buffer
;   	   X=&F8 (sound 3)        X=number of empty spaces in buffer
;   	   X=&F7 (Speech )        X=number of empty spaces in buffer



E74F	BMI &E732   ;if X is -ve then E732 count spaces
E751	BEQ &E75F   ;if X=0 then E75F
E753	CPX #&05    ;else check for Valid channel
E755	BCS &E729   ;if not E729 set X & Y to 0 and exit
E757	LDY &02B9,X ;get conversion values for channel of interest Hi &
E75A	LDA &02B5,X ;lo byte
E75D	TAX         ;X=lo byte
E75E	RTS         ;and exit


E75F	LDA &FE40   ;read system VIA port B
E762	ROR         ;move high nybble to low
E763	ROR         ;
E764	ROR         ;
E765	ROR         ;
E766	EOR #&FF    ;and invert it
E768	AND #&03    ;isolate the FIRE buttons
E76A	LDY &02BE   ;get analogue system flag byte
E76D	STX &02BE   ;store X here
E770	TAX         ;A=X bits 0 and 1 indicate fire buttons
E771	RTS         ;and return


**************************************************************************
**************************************************************************
**                                                                      **
**      OSBYTE  DEFAULT ENTRY POINT                                     **
**                                                                      **
**      pointed to by default BYTEV                                     **
**                                                                      **
**************************************************************************
**************************************************************************


E772	PHA         ;save A
E773	PHP         ;save Processor flags
E774	SEI         ;disable interrupts
E775	STA &EF     ;store A,X,Y in zero page
E777	STX &F0     ;
E779	STY &F1     ;
E77B	LDX #&07    ;X=7 to signal osbyte is being attempted
E77D	CMP #&75    ;if A=0-116
E77F	BCC &E7C2   ;then E7C2
E781	CMP #&A1    ;if A<161
E783	BCC &E78E   ;then E78E
E785	CMP #&A6    ;if A=161-165
E787	BCC &E7C8   ;then EC78
E789	CLC         ;clear carry

E78A	LDA #&A1    ;A=&A1
E78C	ADC #&00    ;

********* process osbyte calls 117 - 160 *****************************

E78E	SEC         ;set carry
E78F	SBC #&5F    ;convert to &16 to &41 (22-65)

E791	ASL         ;double it (44-130)
E792	SEC         ;set carry


E793	STY &F1     ;store Y
E795	TAY         ;Y=A
E796	BIT &025E   ;read econet intercept flag
E799	BPL &E7A2   ;if no econet intercept required E7A2

E79B	TXA         ;else A=X
E79C	CLV         ;V=0
E79D	JSR &E57E   ; to JMP via ECONET vector
E7A0	BVS &E7BC   ;if return with V set E7BC


E7A2	LDA &E5B4,Y ;get address from table
E7A5	STA &FB     ;store it as hi byte
E7A7	LDA &E5B3,Y ;repeat for lo byte
E7AA	STA &FA     ;
E7AC	LDA &EF     ;restore A
E7AE	LDY &F1     ;Y
E7B0	BCS &E7B6   ;if carry is set E7B6

E7B2	LDY #&00    ;else
E7B4	LDA (&F0),Y ;get value from address pointed to by &F0/1 (Y,X)

E7B6	SEC         ;set carry
E7B7	LDX &F0     ;restore X
E7B9	JSR &F058   ;call &FA/B

E7BC	ROR         ;C=bit 0
E7BD	PLP         ;get back flags
E7BE	ROL         ;bit 0=Carry
E7BF	PLA         ;get back A
E7C0	CLV         ;clear V
E7C1	RTS         ;and exit


*************** Process OSBYTE CALLS BELOW &75 **************************

E7C2	LDY #&00    ;Y=0
E7C4	CMP #&16    ;if A<&16
E7C6	BCC &E791   ;goto E791

E7C8	PHP         ;push flags
E7C9	PHP         ;push flags

E7CA	PLA         ;pull flags
E7CB	PLA         ;pull flags
E7CC	JSR &F168   ;offer paged ROMS service 7/8 unrecognised osbyte/word
E7CF	BNE &E7D6   ;if roms don't recognise it then E7D6
E7D1	LDX &F0     ;else restore X
E7D3	JMP &E7BC   ;and exit


E7D6	PLP         ;else pull flags
E7D7	PLA         ;and A
E7D8	BIT &D9B7   ;set V and C
E7DB	RTS         ;and return

E7DC	LDA &EB     ;read cassette critical flag bit 7 = busy
E7DE	BMI &E812   ;if busy then EB12


E7E0	LDA #&08    ;else A=8 to check current Catalogue status
E7E2	AND &E2     ;by anding with CFS status flag
E7E4	BNE &E7EA   ;if not set (not in use) then E7EA RTS
E7E6	LDA #&88    ;A=%10001000
E7E8	AND &BB     ;AND with FS options (short msg bits)
E7EA	RTS         ;RETURN


**************************************************************************
**************************************************************************
**                                                                      **
**      OSWORD  DEFAULT ENTRY POINT                                     **
**                                                                      **
**      pointed to by default WORDV                                     **
**                                                                      **
**************************************************************************
**************************************************************************


E7EB	PHA         ;Push A
E7EC	PHP         ;Push flags
E7ED	SEI         ;disable interrupts
E7EE	STA &EF     ;store A,X,Y
E7F0	STX &F0     ;
E7F2	STY &F1     ;
E7F4	LDX #&08    ;X=8
E7F6	CMP #&E0    ;if A=>224
E7F8	BCS &E78A   ;then E78A with carry set

E7FA	CMP #&0E    ;else if A=>14
E7FC	BCS &E7C8   ;else E7C8 with carry set pass to ROMS & exit

E7FE	ADC #&44    ;add to form pointer to table
E800	ASL         ;double it
E801	BCC &E793   ;goto E793 ALWAYS!! (carry clear E7F8)
    	            ;this reads bytes from table and enters routine


*************************************************************************
*                                                                       *
*       OSWORD  05   ENTRY POINT                                        *
*                                                                       *
*       read a byte from I/O memory                                     *
*                                                                       *
*************************************************************************
;block of 4 bytes set at address pointed to by 00F0/1 (Y,X)
;XY +0  ADDRESS of byte
;   +4  on exit byte read


E803	JSR &E815   ;set up address of data block
E806	LDA (&F9,X) ;get byte
E808	STA (&F0),Y ;store it
E80A	RTS         ;exit


*************************************************************************
*                                                                       *
*       OSWORD  06   ENTRY POINT                                        *
*                                                                       *
*       write a byte to I/O memory                                      *
*                                                                       *
*************************************************************************
;block of 5 bytes set at address pointed to by 00F0/1 (Y,X)
;XY +0  ADDRESS of byte
;   +4  byte to be written


E80B	JSR &E815   ;set up address
E80E	LDA (&F0),Y ;get byte
E810	STA (&F9,X) ;store it
E812	LDA #&00    ;a=0
E814	RTS         ;exit


********************: set up data block *********************************

E815	STA &FA     ;&FA=A
E817	INY         ;Y=1
E818	LDA (&F0),Y ;get byte from block
E81A	STA &FB     ;store it
E81C	LDY #&04    ;Y=4
E81E	LDX #&01    ;X=1
E820	RTS         ;and exit


*************************************************************************
*                                                                       *
*       OSBYTE  00   ENTRY POINT                                        *
*                                                                       *
*       read OS version number                                          *
*                                                                       *
*************************************************************************

E821	BNE &E81E   ;if A <> 0 then exit else print error
E823	BRK         ;
E824	DB  &F7             ;error number
E825	DB  'OS 1.20'       ;error message
E82C	BRK


*************************************************************************
*                                                                       *
*       OSWORD  07   ENTRY POINT                                        *
*                                                                       *
*       make a sound                                                    *
*                                                                       *
*************************************************************************
;block of 8 bytes set at address pointed to by 00F0/1
;XY +0  Channel or +0=Flush, Channel:+1=Hold,Sync
;    2  Amplitude
;    4  Pitch
;    6  Duration
;Y=0 on entry

E82D	INY         ;increment Y
E82E	LDA (&F0),Y ;get channel byte from table
E830	CMP #&FF    ;if its &FF goto speech
E832	BEQ &E88D   ;at E8DD
E834	CMP #&20    ;else if>=&20 set carry
E836	LDX #&08    ;X=8 for unrecognised OSWORD call
E838	BCS &E7CA   ;and if carry set off to E7CA to offer to ROMS
E83A	DEY         ;Y=0
E83B	JSR &E8C9   ;return with Carry set if Flush=1:A=C
E83E	ORA #&04    ;convert to buffer number
E840	TAX         ;A=X
E841	BCC &E848   ;and if carry clear (ex E8C9) then E848

E843	JSR &E1AE   ;else flush buffer
E846	LDY #&01    ;Y=1

E848	JSR &E8C9   ;returns with carry set if H=1;A=S
E84B	STA &FA     ;Sync number =&FA
E84D	PHP         ;ave flags
E84E	LDY #&06    ;Y=6
E850	LDA (&F0),Y ;Get Duration byte
E852	PHA         ;push it

E853	LDY #&04    ;Y=4
E855	LDA (&F0),Y ;get pitch byte
E857	PHA         ;push it
E858	LDY #&02    ;get amplitude byte
E85A	LDA (&F0),Y ;
E85C	ROL         ;H now =bit 0 (carry shifted)
E85D	SEC         ;set carry
E85E	SBC #&02    ;subract 2
E860	ASL         ;multiply by 4
E861	ASL         ;
E862	ORA &FA     ;add S byte (0-3)

    	            ;at this point bit 7=0 for an envelope
    	            ;bits 3-6 give envelope -1, or volume +15
    	            ;(i.e.complemented)
    	            ;bit 2 gives H
    	            ;bits 0-1 =Sync
E864	JSR &E1F8   ;transfer to buffer
E867	BCC &E887   ;if C set on exit succesful transfer so E887

E869	PLA         ;else get back
E86A	PLA         ;stored values
E86B	PLP         ;



*************************************************************************
*                                                                       *
*       OSBYTE  117   ENTRY POINT                                       *
*                                                                       *
*       read VDU status                                                 *
*                                                                       *
*************************************************************************

E86C	LDX &D0     ;get VDU status byte in X
E86E	RTS         ;and return


************* set up sound data for Bell ********************************


E86F	PHP         ;push P
E870	SEI         ;bar interrupts
E871	LDA &0263   ;get bell channel number in A
E874	AND #&07    ; (bits 0-3 only set)
E876	ORA #&04    ;set bit 2
E878	TAX         ;X=A = bell channel number +4=buffer number
E879	LDA &0264   ;get bell amplitude/envelope number
E87C	JSR &E4B0   ;store it in buffer pointed to by X
E87F	LDA &0266   ;get bell duration
E882	PHA         ;save it
E883	LDA &0265   ;get bell frequency
E886	PHA         ;save it