OS SERIES V
GEOFF COX
*************************************************************************
*                                                                       *
*       Check SPEECH System                                             *
*                                                                       *
*************************************************************************

    	            ;X=&10
DB11	BIT &FE40   ;if bit 7 low then we have speech system fitted
DB14	BMI &DB27   ;else goto DB27

DB16	DEC &027B   ;(027B)=&FF to indicate speech present

DB19	LDY #&FF    ;Y=&FF
DB1B	JSR &EE7F   ;initialise speech generator
DB1E	DEX         ;via this
DB1F	BNE &DB19   ;loop
    	            ;X=0
DB21	STX &FE48   ;set T2 timer for speech
DB24	STX &FE49   ;


*********** SCREEN SET UP **********************************************
    	            ;X=0
DB27	LDA &028F   ;get back start up options (mode)
DB2A	JSR &C300   ;then jump to screen initialisation

DB2D	LDY #&CA    ;Y=&CA
DB2F	JSR &E4F1   ;to enter this in keyboard buffer
    	            ;this enables the *KEY 10 facility

********* enter BREAK intercept with Carry Clear ************************

DB32	JSR &EAD9   ;check to see if BOOT address is set up, if so
    	            ;JMP to it

DB35	JSR &F140   ;set up cassette options
DB38	LDA #&81    ;test for tube to FIFO buffer 1
DB3A	STA &FEE0   ;
DB3D	LDA &FEE0   ;
DB40	ROR         ;put bit 0 into carry
DB41	BCC &DB4D   ;if no tube then DB4D
DB43	LDX #&FF    ;else
DB45	JSR &F168   ;issue ROM service call &FF
    	            ;to initialise TUBE system
DB48	BNE &DB4D   ;if not 0 on exit (Tube not initialised) DB4D
DB4A	DEC &027A   ;else set tube flag to show it's active


DB4D	LDY #&0E    ;set current value of PAGE
DB4F	LDX #&01    ;issue claim absolute workspace call
DB51	JSR &F168   ;via F168
DB54	LDX #&02    ;send private workspace claim call
DB56	JSR &F168   ;via F168
DB59	STY &0243   ;set primary OSHWM
DB5C	STY &0244   ;set current OSHWM
DB5F	LDX #&FE    ;issue call for Tube to explode character set etc.
DB61	LDY &027A   ;Y=FF if tube present else Y=0
DB64	JSR &F168   ;and make call via F168

DB67	AND &0267   ;if A=&FE and bit 7 of 0267 is set then continue
DB6A	BPL &DB87   ;else ignore start up message
DB6C	LDY #&02    ;output to screen
DB6E	JSR &DEA9   ;'BBC Computer ' message
DB71	LDA &028D   ;0=warm reset, anything else continue
DB74	BEQ &DB82   ;
DB76	LDY #&16    ;by checking length of RAM
DB78	BIT &028E   ;
DB7B	BMI &DB7F   ;and either
DB7D	LDY #&11    ;
DB7F	JSR &DEA9   ;finishing message with '16k' or '32k'
DB82	LDY #&1B    ;and two newlines
DB84	JSR &DEA9   ;

*********: enter BREAK INTERCEPT ROUTINE WITH CARRY SET (call 1)
DB87	SEC         ;
DB88	JSR &EAD9   ;look for break intercept jump do *TV etc
DB8B	JSR &E9D9   ;set up LEDs in accordance with keyboard status
DB8E	PHP         ;save flags
DB8F	PLA         ;and get back in A
DB90	LSR         ;zero bits 4-7 and bits 0-2 bit 4 which was bit 7
DB91	LSR         ;may be set
DB92	LSR         ;
DB93	LSR         ;
DB94	EOR &028F   ;eor with start-up options which may or may not
DB97	AND #&08    ;invert bit 4
DB99	TAY         ;Y=A
DB9A	LDX #&03    ;make fs initialisation call, passing boot option in Y
DB9C	JSR &F168   ;Eg, RUN, EXEC or LOAD !BOOT file
DB9F	BEQ &DBBE   ;if a ROM accepts this call then DBBE
DBA1	TYA         ;else put Y in A
DBA2	BNE &DBB8   ;if Y<>0 DBB8
DBA4	LDA #&8D    ;else set up standard cassete baud rates
DBA6	JSR &F135   ;via &F135

DBA9	LDX #&D2    ;
DBAB	LDY #&EA    ;
DBAD	DEC &0267   ;decrement ignore start up message flag
DBB0	JSR OSCLI   ;and execute */!BOOT
DBB3	INC &0267   ;restore start up message flag
DBB6	BNE &DBBE   ;if not zero then DBBE

DBB8	LDA #&00    ;else A=0
DBBA	TAX         ;X=0
DBBB	JSR &F137   ;set tape speed

******** Preserve current language on soft RESET ************************

DBBE	LDA &028D   ;get last RESET Type
DBC1	BNE &DBC8   ;if not soft reset DBC8

DBC3	LDX &028C   ;else get current language ROM address
DBC6	BPL &DBE6   ;if +ve (language available) then skip search routine



*************************************************************************
*                                                                       *
*       SEARCH FOR LANGUAGE TO ENTER (Highest priority)                 *
*                                                                       *
*************************************************************************

DBC8	LDX #&0F    ;set pointer to highest available rom

DBCA	LDA &02A1,X ;get rom type from map
DBCD	ROL         ;put hi-bit into carry, bit 6 into bit 7
DBCE	BMI &DBE6   ;if bit 7 set then ROM has a language entry so DBE6

DBD0	DEX         ;else search for language until X=&ff
DBD1	BPL &DBCA   ;


*************** check if tube present ***********************************

DBD3	LDA #&00    ;if bit 7 of tube flag is set BMI succeeds
DBD5	BIT &027A   ;and TUBE is connected else
DBD8	BMI &DC08   ;make error

********* no language error ***********************************************

DBDA	BRK         ;
DBDB	DB  &F9     ;error number
DBDC	DB  'Language?'     ;message
DBE5	BRK         ;


DBE6	CLC         ;


*************************************************************************
*                                                                       *
*       OSBYTE 142 - ENTER LANGUAGE ROM AT &8000                        *
*                                                                       *
*       X=rom number C set if OSBYTE call clear if initialisation       *
*                                                                       *
*************************************************************************

DBE7	PHP         ;save flags
DBE8	STX &028C   ;put X in current ROM page
DBEB	JSR &DC16   ;select that ROM
DBEE	LDA #&80    ;A=128
DBF0	LDY #&08    ;Y=8
DBF2	JSR &DEAB   ;display text string held in ROM at &8008,Y
DBF5	STY &FD     ;save Y on exit (end of language string)
DBF7	JSR OSNEWL  ;two line feeds
DBFA	JSR OSNEWL  ;are output
DBFD	PLP         ;then get back flags
DBFE	LDA #&01    ;A=1 required for language entry
DC00	BIT &027A   ;check if tube exists
DC03	BMI &DC08   ;and goto DC08 if it does
DC05	JMP &8000   ;else enter language at &8000


*************************************************************************
*                                                                       *
*       TUBE FOUND, ENTER TUBE SOFTWARE                                 *
*                                                                       *
*************************************************************************

DC08	JMP &0400   ;enter tube environment


*************************************************************************
*                                                                       *
*       OSRDRM entry point                                              *
*                                                                       *
*       get byte from PHROM or page ROM                                 *
*       Y= rom number, address is in &F6/7                              *
*************************************************************************

DC0B	LDX &F4     ;get current ROM number into X
DC0D	STY &F4     ;store new number in &F4
DC0F	STY &FE30   ;switch in ROM
DC12	LDY #&00    ;get current PHROM address
DC14	LDA (&F6),Y ;and get byte

******** Set up Sideways Rom latch and RAM copy *************************
    	    ;on entry X=ROM number

DC16	STX &F4     ;RAM copy of rom latch
DC18	STX &FE30   ;write to rom latch
DC1B	RTS         ;and return



**************************************************************************
**************************************************************************
**                                                                      **
**      MAIN IRQ Entry point                                            **
**                                                                      **
**                                                                      **
**************************************************************************
**************************************************************************
;ON ENTRY STACK contains        STATUS REGISTER,PCH,PCL                 ;

DC1C	STA &FC     ;save A
DC1E	PLA         ;get back status (flags)
DC1F	PHA         ;and save again
DC20	AND #&10    ;check if BRK flag set
DC22	BNE &DC27   ;if so goto DC27
DC24	JMP (&0204) ;else JMP (IRQ1V)


*************************************************************************
*                                                                       *
*               BRK handling routine                                    *
*                                                                       *
*************************************************************************

DC27	TXA         ;save X on stack
DC28	PHA         ;
DC29	TSX         ;get status pointer
DC2A	LDA &0103,X ;get Program Counter lo
DC2D	CLD         ;
DC2E	SEC         ;set carry
DC2F	SBC #&01    ;subtract 2 (1+carry)
DC31	STA &FD     ;and store it in &FD
DC33	LDA &0104,X ;get hi byte
DC36	SBC #&00    ;subtract 1 if necessary
DC38	STA &FE     ;and store in &FE
DC3A	LDA &F4     ;get currently active ROM
DC3C	STA &024A   ;and store it in &24A
DC3F	STX &F0     ;store stack pointer in &F0
DC41	LDX #&06    ;and issue ROM service call 6
DC43	JSR &F168   ;(User BRK) to roms
    	            ;at this point &FD/E point to byte after BRK
    	            ;ROMS may use BRK for their own purposes

DC46	LDX &028C   ;get current language
DC49	JSR &DC16   ;and activate it
DC4C	PLA         ;get back original value of X
DC4D	TAX         ;
DC4E	LDA &FC     ;get back original value of A
DC50	CLI         ;allow interrupts
DC51	JMP (&0202) ;and JUMP via BRKV (normally into current language)



*************************************************************************
*                                                                       *
*       DEFAULT BRK HANDLER                                             *
*                                                                       *
*************************************************************************

DC54	LDY #&00    ;Y=0 to point to byte after BRK
DC56	JSR &DEB1   ;print message

DC59	LDA &0267   ;if BIT 0 set and DISC EXEC error
DC5C	ROR         ;occurs
DC5D	BCS &DC5D   ;hang up machine!!!!

DC5F	JSR OSNEWL  ;else print two newlines
DC62	JSR OSNEWL  ;
DC65	JMP &DBB8   ;and set tape speed before entering current
    	            ;language

DC68	SEC         ;set carry
DC69	ROR &024F   ;and rotate right to set RS423 busy flag
DC6C	BIT &0250   ;check bit 7 of current ACIA control register
DC6F	BPL &DC78   ;if interrupts NOT enabled DC78
DC71	JSR &E741   ;else E741 to check if serial buffer full
DC74	LDX #&00    ;
DC76	BCS &DC7A   ;if carry set goto DC7A to transfer data

DC78	LDX #&40    ;X=&40
DC7A	JMP &E17A   ;and transfer data

DC7D	LDY &FE09   ;read serial data from ACIA
DC80	AND #&3A    ;and %0011 1010
DC82	BNE &DCB8   ;if no 0 then DCB8

DC84	LDX &025C   ;read RS423 input suppression flag
DC87	BNE &DC92   ;if not 0 then DC92 ignore RS423 input
DC89	INX         ;else X=X+1
DC8A	JSR &E4F3   ;put byte in buffer
DC8D	JSR &E741   ;count buffer
DC90	BCC &DC78   ;and if carry clear (buffer not full) back to DC78
DC92	RTS         ;else return
    	            ;
*************************************************************************
*                                                                       *
*       Main IRQ Handling routines, default IRQIV destination           *
*                                                                       *
*************************************************************************


DC93	CLD         ;clear decimal flag
DC94	LDA &FC     ;get original value of A
DC96	PHA         ;save it
DC97	TXA         ;save X
DC98	PHA         ;
DC99	TYA         ;and Y
DC9A	PHA         ;
DC9B	LDA #&DE    ;A=&DE
DC9D	PHA         ;store it
DC9E	LDA #&81    ;save &81
DCA0	PHA         ;store it (an RTS will now jump to DE82)
DCA1	CLV         ;clear V flag
DCA2	LDA &FE08   ;get value of status register of ACIA
DCA5	BVS &DCA9   ;if parity error then DCA9
DCA7	BPL &DD06   ;else if no interrupt requested DD06

DCA9	LDX &EA     ;read RS423 timeout counter
DCAB	DEX         ;decrement it
DCAC	BMI &DCDE   ;and if <0 DCDE
DCAE	BVS &DCDD   ;else if >&40 DCDD (RTS to DE82)
DCB0	JMP &F588   ;else read ACIA via F588

DCB3	LDY &FE09   ;read ACIA data
DCB6	ROL         ;
DCB7	ASL         ;
DCB8	TAX         ;X=A
DCB9	TYA         ;A=Y
DCBA	LDY #&07    ;Y=07
DCBC	JMP &E494   ;check and service EVENT 7 RS423 error

DCBF	LDX #&02    ;read RS423 output buffer
DCC1	JSR &E460   ;
DCC4	BCC &DCD6   ;if C=0 buffer is not empty goto DCD6
DCC6	LDA &0285   ;else read printer destination
DCC9	CMP #&02    ;is it serial printer??
DCCB	BNE &DC68   ;if not DC68
DCCD	INX         ;else X=3
DCCE	JSR &E460   ;read printer buffer
DCD1	ROR &02D2   ;rotate to pass carry into bit 7
DCD4	BMI &DC68   ;if set then DC68
DCD6	STA &FE09   ;pass either printer or RS423 data to ACIA
DCD9	LDA #&E7    ;set timeout counter to stored value
DCDB	STA &EA     ;
DCDD	RTS         ;and exit (to DE82)


    	            ;A contains ACIA status
DCDE	AND &0278   ;AND with ACIA bit mask (normally FF)
DCE1	LSR         ;rotate right to put bit 0 in carry
DCE2	BCC &DCEB   ;if carry clear receive register not full so DCEB
DCE4	BVS &DCEB   ;if V is set then DCEB
DCE6	LDY &0250   ;else Y=ACIA control setting
DCE9	BMI &DC7D   ;if bit 7 set receive interrupt is enabled so DC7D

DCEB	LSR         ;put BIT 2 of ACIA status into
DCEC	ROR         ;carry if set then Data Carrier Detected applies
DCED	BCS &DCB3   ;jump to DCB3

DCEF	BMI &DCBF   ;if original bit 1 is set TDR is empty so DCBF
DCF1	BVS &DCDD   ;if V is set then exit to DE82

DCF3	LDX #&05    ;X=5
DCF5	JSR &F168   ;issue rom call 5 'unrecognised interrupt'
DCF8	BEQ &DCDD   ;if a rom recognises it then exit to DE82
DCFA	PLA         ;otherwise get back DE82 address from stack
DCFB	PLA         ;
DCFC	PLA         ;and get back X, Y, and A
DCFD	TAY         ;
DCFE	PLA         ;
DCFF	TAX         ;
DD00	PLA         ;
DD01	STA &FC     ;&FC=A
DD03	JMP (&0206) ;and offer to the user via IRQ2V



*************************************************************************
*                                                                       *
* VIA INTERUPTS ROUTINES                                                *
*                                                                       *
*************************************************************************

DD06	LDA &FE4D   ;read system VIA interrupt flag register
DD09	BPL &DD47   ;if bit 7=0 the VIA has not caused interrupt
    	            ;goto DD47
DD0B	AND &0279   ;mask with VIA bit mask
DD0E	AND &FE4E   ;and interrupt enable register
DD11	ROR         ;rotate right twice to check for IRQ 1 (frame sync)
DD12	ROR         ;
DD13	BCC &DD69   ;if carry clear then no IRQ 1, else
DD15	DEC &0240   ;decrement vertical sync counter
DD18	LDA &EA     ;A=RS423 Timeout counter
DD1A	BPL &DD1E   ;if +ve then DD1E
DD1C	INC &EA     ;else increment it
DD1E	LDA &0251   ;load flash counter
DD21	BEQ &DD3D   ;if 0 then system is not in use, ignore it
DD23	DEC &0251   ;else decrement counter
DD26	BNE &DD3D   ;and if not 0 go on past reset routine

DD28	LDX &0252   ;else get mark period count in X
DD2B	LDA &0248   ;current VIDEO ULA control setting in A
DD2E	LSR         ;shift bit 0 into C to check if first colour
DD2F	BCC &DD34   ;is effective if so C=0 jump to DD34

DD31	LDX &0253   ;else get space period count in X
DD34	ROL         ;restore bit
DD35	EOR #&01    ;and invert it
DD37	JSR &EA00   ;then change colour

DD3A	STX &0251   ;&0251=X resetting the counter

DD3D	LDY #&04    ;Y=4 and call E494 to check and implement vertical
DD3F	JSR &E494   ;sync event (4) if necessary
DD42	LDA #&02    ;A=2
DD44	JMP &DE6E   ;clear interrupt 1 and exit


*************************************************************************
*                                                                       *
*       PRINTER INTERRUPT USER VIA 1                                    *
*                                                                       *
*************************************************************************

DD47	LDA &FE6D   ;Check USER VIA interrupt flags register
DD4A	BPL &DCF3   ;if +ve USER VIA did not call interrupt
DD4C	AND &0277   ;else check for USER IRQ 1
DD4F	AND &FE6E   ;
DD52	ROR         ;
DD53	ROR         ;
DD54	BCC &DCF3   ;if bit 1=0 the no interrupt 1 so DCF3
DD56	LDY &0285   ;else get printer type
DD59	DEY         ;decrement
DD5A	BNE &DCF3   ;if not parallel then DCF3
DD5C	LDA #&02    ;reset interrupt 1 flag
DD5E	STA &FE6D   ;
DD61	STA &FE6E   ;disable interrupt 1
DD64	LDX #&03    ;and output data to parallel printer
DD66	JMP &E13A   ;


***********************************************************************
*                                                                       *
*       SYSTEM INTERRUPT 5   Speech                                     *
*                                                                       *
*************************************************************************

DD69	ROL         ;get bit 5 into bit 7
DD6A	ROL         ;
DD6B	ROL         ;
DD6C	ROL         ;
DD6D	BPL &DDCA   ;if not set the not a speech interrupt so DDCA

DD6F	LDA #&20    ;clear interrupt flag
DD71	LDX #&00    ;
DD73	STA &FE4D   ;
DD76	STX &FE49   ;and zer0 hi byte of T2 Timer
DD79	LDX #&08    ;&FB=8
DD7B	STX &FB     ;
DD7D	JSR &E45B   ;and examine buffer 8
DD80	ROR &02D7   ;shift carry into bit 7
DD83	BMI &DDC9   ;and if set buffer is empty so exit
DD85	TAY         ;else Y=A
DD86	BEQ &DD8D   ;
DD88	JSR &EE6D   ;control speech chip
DD8B	BMI &DDC9   ;if negative exit
DD8D	JSR &E460   ;else get a byte from buffer
DD90	STA &F5     ;store it to indicate speech or file rom
DD92	JSR &E460   ;get another byte
DD95	STA &F7     ;store it
DD97	JSR &E460   ;and another
DD9A	STA &F6     ;giving address  to be accessed in paged ROM
DD9C	LDY &F5     ;Y=&F5
DD9E	BEQ &DDBB   ;and if =0 then DDBB
DDA0	BPL &DDB8   ;else if +ve DDB8
DDA2	BIT &F5     ;if bit 6 of F5 =1 (&F5)>&40
DDA4	BVS &DDAB   ;then DDAB
DDA6	JSR &EEBB   ;else continue for more speech processing
DDA9	BVC &DDB2   ;if bit 6 clear then DDB2
DDAB	ASL &F6     ;else double address in &F6/7
DDAD	ROL &F7     ;
DDAF	JSR &EE3B   ;and call EE3B
DDB2	LDY &0261   ;get speech enable/disable flag into Y
DDB5	JMP &EE7F   ;and JMP to EE7F

DDB8	JSR &EE7F   ;Call EE7F
DDBB	LDY &F6     ;get address pointer in Y
DDBD	JSR &EE7F   ;
DDC0	LDY &F7     ;get address pointer high in Y
DDC2	JSR &EE7F   ;
DDC5	LSR &FB     ;
DDC7	BNE &DD7D   ;
DDC9	RTS         ;and exit