 
;   EXAMPLE.ASM         (6502 Microprocessor)
;          
 
            processor   6502
 
            mac     ldax
            lda     [{1}]
            ldx     [{1}]+1
            endm
            mac     ldaxi
            lda     #<[{1}]
            ldx     #>[{1}]
            endm
            mac     stax
            sta     [{1}]
            stx     [{1}]+1
            endm
            mac     pushxy
            txa
            pha
            tya
            pha
            endm
            mac     popxy
            pla
            tay
            pla
            tax
            endm
            mac     inc16
            inc     {1}
            bne     .1
            inc     {1}+1
.1          
            endm
 
STOP1       equ %00000000           ;CxCTL  1 Stop bit
STOP2       equ %10000000           ;CxCTL  2 Stop bits (WL5:1.5, WL8&par:1)
WL5         equ %01100000           ;CxCTL  Wordlength
WL6         equ %01000000
WL7         equ %00100000
WL8         equ %00000000
RCS         equ %00010000           ;CxCTL  1=Select baud, 0=ext. receiver clk
 
B76800      equ %0000               ;CxCTL  Baud rates  (1.2288 Mhz clock)
B75         equ %0001
B100        equ %0010
B150        equ %0011
B200        equ %0100
B300        equ %0101
B400        equ %0110
B600        equ %0111
B800        equ %1000
B1200       equ %1001
B1600       equ %1010
B2400       equ %1011
B3200       equ %1100
B4800       equ %1101
B6400       equ %1110
B12800      equ %1111
 
PARODD      equ %00100000           ;CxCMD  Select Parity
PAREVEN     equ %01100000
PARMARK     equ %10100000
PARSPACE    equ %11100000
PAROFF      equ %00000000
 
RECECHO     equ %00010000           ;CxCMD  Receiver Echo mode
TMASK       equ %00001100
TDISABLE    equ %00000000           ;CxCMD  Transmitter modes
TDISABLER   equ %00001000           ;RTS stays asserted
TENABLE     equ %00000100
TBREAK      equ %00001100           ;send break
 
UA_IRQDSBL  equ %00000010
DTRRDY      equ %00000001           ;~DTR output is inverted (low)
 
SR_PE       equ %00000001           ;CxSTAT  Status
SR_FE       equ %00000010           ;NOTE: writing dummy data causes RESET
SR_OVRUN    equ %00000100
SR_RDRFULL  equ %00001000
SR_TDREMPTY equ %00010000
SR_DCD      equ %00100000
SR_DSR      equ %01000000
SR_INTPEND  equ %10000000
 
 
T1_OEPB7    equ %10000000           ;x_ACR
T1_FREERUN  equ %01000000           ;T1 free running mode
T1_ONESHOT  equ %00000000
T2_ICPB6    equ %00100000           ;T2 counts pulses on PB6
T2_ONESHOT  equ %00000000           ;T2 counts phase2 transitions
SRC_OFF     equ %00000000           ;shift register control
SRC_INT2    equ %00000100
SRC_INPH2   equ %00001000
SRC_INEXT   equ %00001100
SRC_OUTFR   equ %00010000           ;free running output using T2
SRC_OUTT2   equ %00010100
SRC_OUTPH2  equ %00011000
SRC_OUTEXT  equ %00011100
PBLE        equ %00000010           ;on CB1 transition (in/out).
PALE        equ %00000001           ;on CA1 transition (in).  data retained
 
                                    ;x_PCR
CB2_I_NEG   equ %00000000           ;interrupt on neg trans, r/w ORB clears
CB2_I_NEGI  equ %00100000           ; same, but r/w ORB does not clear int
CB2_I_POS   equ %01000000           ;interrupt on pos trans, r/w ORB clears
CB2_I_POSI  equ %01100000           ; same, but r/w ORB does not clear int
CB2_O_HSHAK equ %10000000           ;CB2=0 on r/w ORB, CB2=1 on CB1 transition
CB2_O_PULSE equ %10100000           ;CB2=0 for one clock after r/w ORB
CB2_O_MANLO equ %11000000           ;CB2=0
CB2_O_MANHI equ %11100000           ;CB2=1
 
CA2_I_NEG   equ %00000000           ;interrupt on neg trans, r/w ORA clears
CA2_I_NEGI  equ %00100000           ; same, but r/w ORA does not clear int
CA2_I_POS   equ %01000000           ;interrupt on pos trans, r/w ORA clears
CA2_I_POSI  equ %01100000           ; same, but r/w ORA does not clear int
CA2_O_HSHAK equ %10000000           ;CA2=0 on r/w ORA, CA2=1 on CA1 transition
CA2_O_PULSE equ %10100000           ;CA2=0 for one clock after r/w ORA
CA2_O_MANLO equ %11000000           ;CA2=0
CA2_O_MANHI equ %11100000           ;CA2=1
 
 
CB1_THI     equ %00010000
CB1_TLO     equ %00000000
CA1_THI     equ %00000001
CA1_TLO     equ %00000000
 
VIRPEND     equ %10000000           ;x_IFR
IRENABLE    equ %10000000           ;x_IER  1's enable ints  0=no change
IRDISABLE   equ %00000000           ;x_IER  1's disable ints 0=no change
 
IRT1        equ %01000000
IRT2        equ %00100000
IRCB1       equ %00010000
IRCB2       equ %00001000
IRSR        equ %00000100
IRCA1       equ %00000010
IRCA2       equ %00000001
 
            seg.u   bss
            org     $0000           ;RAM (see below)
            org     $2000           ;unused
            org     $4000           ;unused
 
            org     $6000           ;6551 CHANNEL #1
C1DATA      ds      1
C1STAT      ds      1
C1CMD       ds      1
C1CTL       ds      1
 
            org     $8000           ;6551 CHANNEL #2
C2DATA      ds      1
C2STAT      ds      1
C2CMD       ds      1
C2CTL       ds      1
 
            org     $A000           ;6522 (HOST COMM)
H_ORB       ds      1
H_ORAHS     ds      1               ;with CA2 handshake
H_DDRB      ds      1
H_DDRA      ds      1
H_T1CL      ds      1               ;read clears interrupt flag
H_T1CH      ds      1               ;write clears interrupt flag
H_T1CLL     ds      1
H_T1CHL     ds      1               ;write clears interrupt flag
H_T2CL      ds      1               ;read clears interrupt flag
H_T2CH      ds      1               ;write clears interrupt flag
H_SR        ds      1
H_ACR       ds      1
H_PCR       ds      1
H_IFR       ds      1
H_IER       ds      1
H_ORA       ds      1               ;no CA2 handshake
 
            org     $C000           ;6522 (IO COMM)
I_ORB       ds      1
I_ORAHS     ds      1               ;   (same comments apply)
I_DDRB      ds      1
I_DDRA      ds      1
I_T1CL      ds      1
I_T1CH      ds      1
I_T1CLL     ds      1
I_T1CHL     ds      1
I_T2CL      ds      1
I_T2CH      ds      1
I_SR        ds      1
I_ACR       ds      1
I_PCR       ds      1
I_IFR       ds      1
I_IER       ds      1
I_ORA       ds      1
 
 
          
            ;   --------------------------   ZERO PAGE   -------------------
            seg.u   data
            org     $00
 
            ;   --------------------------  NORMAL RAM   -------------------
            org     $0100
 
RAMEND      equ     $2000
 
            ;   --------------------------     CODE      -------------------
 
            seg     code
            org     $F000
PROMBEG     equ     .
 
RESET       subroutine
            sei                 ;disable interrupts
            ldx     #$FF        ;reset stack
            txs
 
            lda     #$FF
            sta     H_DDRA
            sta     C1STAT      ;reset 6551#1 (garbage data)
            sta     C2STAT      ;reset 6551#2
            lda     #$7F        ;disable all 6522 interrupts
            sta     H_IER
            sta     I_IER
 
            lda     #%00010000  ;76.8 baud, 8 bits, 1 stop
            sta     C1CTL
            lda     #%00000101  ;no parity, enable transmitter & int
            sta     C1CMD
            lda     #$AA        ;begin transmision
            sta     C1DATA
 
            lda     #%00011111  ;9600 baud, 8 bits, 1 stop
            sta     C2CTL
            lda     #%00000101
            sta     C2CMD
            lda     #$41
            sta     C2DATA
 
            cli                 ;enable interrupts
 
.1          jsr     LOAD
            jsr     SAVE
            jmp     .1
 
LOAD        subroutine
 
            ldx     #0
.1          txa
            sta     $0500,x
            inx
            bne     .1
            rts
 
SAVE        subroutine
 
            ldx     #0
.2          lda     $0500,x
            sta     H_ORA
            inx
            bne     .2
            rts
 
NMI         rti
 
            subroutine
IRQ         bit     C1STAT
            bpl     .1
            pha
            lda     #$AA
            sta     C1DATA
            lda     C1DATA
            pla
            rti
.1          bit     C2STAT
            bpl     .2
            pha
            lda     #$41
            sta     C2DATA
            lda     C2DATA
            pla
.2          rti
 
            ;   VECTOR  ------------------------------------------------
 
            seg     vector
            org     $FFFA
            dc.w    NMI
            dc.w    RESET
            dc.w    IRQ
 
PROMEND     equ     .
 
 
