.CR     8085
        .TF     5036A.BIN,BIN
        .LF     5036A

RESET:  MVI     H,$08       ;PAGE ADRS OF WRITE TEST RAM
        MOV     A,M         ;TEST RAM CELL DATA
        CMA                 ;COMPLEMENT IT
        MOV     M,A         ;STORE IT BCK IN RAM
        JMP     STRT        ;TO CONTINUE
        ;
        ;RS1 IS MAIN ENTRY POINT TO MONITOR
        ;
RS1:    SHLD    TSAVH       ;SAVE USER HL CONTENTS IN RAM
        OUT     $10         ;UNPROTECT RAM
        JMP     TRP         ;CONTINUE
        ;
        ;BEEP PRODUCES A FIXED TONE FREQ + DURATION
        ;
BEEP:   MVI     B,FREQ      ;DEFAULT FREQUENCY
BEEP1:  MVI     D,DURA      ;DEFAULT DURATION
        JMP     BEEP2       ;CONTINUE
        NOP
        ;
        ;STDM STORES DISP MESSAGE AT DE ADRS IN UDSP RAM
        ;
STDM:   PUSH    B
        LXI     H,UDSP0     ;ADRS OF UNDECODED DISPLAY DIGIT 0
        JMP     SDM         ;CONTINUE
        NOP
RS4:    JMP     RS4C        ;USER ROUTINE
        NOP
TRAP:   JMP     RS1         ;SAV USER REGS+RETURN TO MONITOR
        NOP
RS5:    JMP     RS5C        ;USER ROUTINE
        NOP
RS55:   JMP     RS55C       ;USER ROUTINE
        NOP
RS6:    JMP     RS6C        ;USER ROUTINE
        NOP
RS65:   JMP     RS65C       ;USER ROUTINE
        NOP
RS7:    JMP     STRT6       ;RETURN TO MONITOR
        NOP
RS75:   RST     2           ;BEEP
        JMP     SATL1       ;SA TEST LOOP
        ;
        ;POWER-UP SELF TEST AND INITIALIZE
        ;
STRT:   CMP     M           ;SEE IF DATA IS STORED IN RAM
        JNZ     PPER        ;IF RAM WAS INITIALIZED (RUN MODE)
        LXI     SP,MSP      ;INITIALIZE MONITOR SP
        XRA     A           ;CLEAR A
        MOV     H,A         ;CLEAR H     FIRST ADRS
        MOV     L,A         ;CLEAR L       OR ROM
        OUT     LOUT        ;TURN ON OUTPUT LEDS
        ;
        ;ROM SELF TEST
        ;
STRT1:  ADD     M           ;ADD ROM DATA TO A
        INX     H           ;POINT TO NEXT ROM ADRS
        MOV     C,A         ;SAVE A RESIDUE IN C
        MVI     A,$08       ;LAST ADRS OF ROM+1 (MSBYTE)
        CMP     H           ;COMPARE IT TO H
        MOV     A,C         ;RESTORE RESIDUE TO A
        JNZ     STRT1       ;IF LAST ROM ADRS NOT 0800
        DCX     H           ;PONT HL TO 07FF CHECKSUM VALUE
        SUB     M           ;SUSTRACT CHECKSUM FOR A RESIDUE
        CMP     M           ;COMPARE RESIDUE TO CHECKSUM
        MVI     B,$04       ;IC 4 (ROM) MESSAGE
        JNZ     MERR1       ;IF NOT A MATCH
        ;
        ;RAM SELF TEST
        ;
        XRA     A           ;CLEAR A
        LXI     H,$0800     ;1ST RAM ADDR
        MVI     B,$03       ;ADD CONSTANT
STRT2:  MOV     M,A         ;STORE DATA IN RAM
        ADD     B           ;ADD 3 TO A
        INX     H           ;POINT TO NEXT RAM ADRS
        MOV     C,A         ;SAVE A
        MOV     A,H         ;GET MSBYTE ADRS
        CPI     $0C         ;LAST RAM ADRS+1
        MOV     A,C         ;RESTORE A
        JNZ     STRT2       ;IF NOT LAST RAM ADRS
        XRA     A           ;CLEAR A
        LXI     H,$0800     ;1ST RAM ADRS
STRT3:  CMP     M           ;DID DATA GET STORED IN RAM?
        JNZ     MERR        ;IF DATA NOT SAME
        CMA
        MOV     M,A         ;STORE COMPLEMENT BACK IN RAM
        CMP     M           ;DID IT STORE?
        JNZ     MERR        ;IF NOT
        CMA                 ;UNCOMPLEMENT A
        ADD     B           ;ADD 3 TO A
        INX     H           ;NEXT RAM ADDR
        MOV     C,A         ;SAVE A
        MOV     A,H         ;GET MSBYTE ADRS
        CPI     $0C         ;LAST RAM ADRS+1
        MOV     A,C         ;RESTORE A
        JNZ     STRT3       ;TO CHECK NEXT RAM LOCATION
        ;
        ;DISPLAY TEST
        ;
        MVI     B,$00       ;CLEAR LOOP COUNTER
STRT4:  LXI     D,ALL       ;DISPLAY MESSAGE POINTER  ALL SEGS
        RST     3           ;GET MESSAGE
        CALL    DCD         ;UPDATE DISPLAY
        DCR     B           ;DECR LOOP COUNTER
        JNZ     STRT4       ;IF NOT DONE
        ;
        ;CLEAR RAM (STORE 00 IN ALL LOCATIONS)
        ;
        MVI     B,$00       ;CLEAR B
        MVI     A,$0C       ;MSBYTE ADRS OF TOP OF RAM+1
        LXI     H,$0800     ;1ST ADRS OF RAM
STRT5:  MOV     M,B         ;CLEAR RAM LOCATION
        INX     H           ;POINT TO NEXT LOCATION
        CMP     H           ;TO LAST RAM ADRS+1
        JNZ     STRT5       ;IF NOT DONE CLEARING RAM
        MVI     A,$FF       ;SET A TO ALL ONES
        OUT     LOUT        ;TURN OF OUTPUT LEDS
STRT6:  RST     2           ;SIGNAL START-UP DONE
        ;
        ; INITIALIZE REGISTERS
        ;
        LXI     H,USP       ;USER SP DEFAULT VALUE
        SHLD    SAVSL       ;STORE IT IN RAM
        LXI     H,RS        ;RUN STATUS WORD ADRS
        MVI     M,$00       ;SET STATUS TO MONITOR
        MVI     A,DIM       ;DEFAULT INTERRUPT MASK
        STA     SAVIM       ;STORE IT IN RAM
STRT7:  LXI     H,PC        ;DEFAULT PC
        SHLD    SAVPC       ;STORE IT IN RAM
        MVI     A,$FF       ;RST7 INSTR CODE
        STA     TPR         ;STORE IT IN TOP OF PROTECTED RAM
        STA     UR          ;STORE IT IN UPPER RAM BELOW LINKS
        JMP     TRP3        ;JUMP TO MONITOR
        ;
        ;PUSH-POP ERROR ROUTINE
        ;
PPER:   LXI     SP,MSP      ;SET MONITOR SP
        LXI     H,PC        ;DEFAULT PC
        SHLD    SAVPC       ;STORE IT IN RAM
        RST     2           ;SIGNAL AN ERROR
        XRA     A           ;CLEAR A
        STA     RS          ;SET RUN STATUS TO MONITOR
        LXI     D,PPM       ;PUSH-POP ERROR MESSAGE ADRS
        JMP     TRP4
        ;
        ;MEMORY ERROR SORT
        ;
MERR:   MVI     B,$06       ;IC6 RAM FAIL MESSAGE
        XRA     M           ;GET DIFFERENCE INTO A
        ANI     $0F         ;TEST 4LSB'S OF IC6
        JZ      MERR1       ;IF PROBLEM IN IC6
        DCR     B           ;SET B TO IC5
MERR1:  LXI     D,ICX       ;ICX MESSAGE ADRS
        RST     3           ;GET MESSAGE
        LXI     H,UDSP2     ;ADRS OF ICX IN UDSP RAM
        MOV     M,B         ;STORE IC NUMBER IN UDSP2
MERR2:  CALL    DCD         ;DISPLAY MESSAGE
        JMP     MERR2       ;LOOP MESSAGE
        ;
        ;RS1 IS MAIN ENTRY POINT TO MONITOR
        ;
TRP:    LXI     H,$0000     ;CLEAR H,L
        JNC     TRP1        ;NO USER CARRY WILL BYPASS DCXH
        DCX     H           ;SET H,L TO FF IF CARRY PRESENT
TRP1:   DAD     SP          ;GET SP VALUE INTO HL, RESTORE CY
        JNC     TRP2        ;IF JNC TO TRP1 OCCURED
        INX     H           ;IF DCXH OCCURED BECAUSE OF CARRY
TRP2:   SHLD    TSAVSP      ;SAVE USER SP IN RAM
        LXI     SP,TSAVSP   ;TSAVA+1 ADRS
        PUSH    PSW         ;SAVE PSW AND A IN RAM
        LXI     H,RS        ;RUN STATUS ADRS
        XRA     A           ;CLEAR A
        CMP     M           ;FOR RUN STATUS=MONITOR
        STA     UDSP6       ;CLEAR DATA MODIFY FLAG
        JNZ     TRP6        ;IF CAME FROM USER PROGRAM
TRP3:   LXI     D,DMT       ;ULAB MESSAGE ADRS
        EI
TRP4:   MVI     A,DIM       ;DEFAULT INTERRUPT MASK
        SIM                 ;SET IT TO ENABLE RST7.5 ONLY
        OUT     $10         ;UNPROTECT RAM
        RST     3           ;GET MESSAGE
TRP5:   CALL    KIND        ;INPUT KEYS
        CALL    CFETA       ;LOOK FOR ACCEPTABLE KEYS
        JMP     TRP5        ;TRY AGAIN
TRP6:   MOV     M,A         ;STORE 0 IN RS TO SET MONITOR
        ;
        ;SAVE REGISTERS
        ;
        POP     PSW         ;FROM TSAVPSW IN RAM
        POP     H           ;GETS USER SP VALUE FROM RAM
        INX     H           ;USER SP
        INX     H           ;USER SP
        SHLD    SAVSL       ;SAVE SP IN RAM
        DCX     H           ;USER SP
        DCX     H           ;USER SP
        SPHL                ;RESTORE SP
        POP     H           ;GET RETURN ADRS TO USER PROGRAM
        SHLD    SAVPC       ;STORE IT IN RAM
        LXI     SP,$0BE8    ;ADRS OF SAVA+1
        LHLD    TSAVH       ;RESTORE H,L
        PUSH    PSW         ;INTO SAVPSW
        PUSH    B           ;INTO SAVB
        PUSH    D           ;INTO SAVD
        PUSH    H           ;INTO SAVH
        RIM                 ;GET IM
        STA     SAVIM       ;STORE IT IN RAM
TRP7:   LXI     SP,SAVPC    ;POINT IT TO USER SP
        POP     B           ;AND POP IT IN BC
        LXI     SP,MSP      ;RESTORE MONITOR SP
        JMP     FETA3
        ;
        ;KEY INPUT AND DECODE
        ;
KIND:   PUSH    D
        PUSH    H
KIND1:  CALL    DCD         ;UPDATE DISPLAY AND WAIT
        CALL    KPU         ;CHK FOR PUSHED KEY
        JNZ     KIND1       ;IF KEY STILL PUSHED
KIND2:  CALL    DCD         ;UDPATE DISP AND WAIT
        CALL    KPU         ;CHK FOR PUSHED KEY
        JZ      KIND2       ;IF KEY NOT PUSHED
        LXI     H,UDKY      ;ADRS OF FIRST KEY ROW TO SCAN
        MVI     D,$FF       ;LOAD ROW COUNTER TO 0-1
KIND3:  MOV     A,M         ;GET ROW N KEY DATA
        CPI     $F7         ;IS IT THE HDWR STEP KEY?
        JZ      KIND5       ;YES JUMPS
        CMA                 ;INVERT KEY DATA
        INR     L           ;NEXT ROW
        INR     D           ;NEXT TABLE BLOCK
        ANA     A           ;TEST ROW N FOR 0
        JZ      KIND3       ;JUMP IF KEY NOT PUSHED
        CPI     $04         ;SEE IF D3=1
        JNZ     KIND4       ;IF SO
        DCR     A           ;ELSE SET A=3
KIND4:  ADD     D           ;ADD 3X THE ROW N TO
        ADD     D           ;GET THE TABLE OFFSET
        ADD     D
        MOV     E,A         ;STORE TABLE INDEX
        MVI     D,$00       ;CLEAR MS BYTE OF DE
        LXI     H,KIT-1     ;ADRS OF KEY CODE TABLE
        DAD     D           ;ADD INDEX TO TABLE ADRS
        MOV     A,M         ;PUT KEY CODE IN A
KIND5:  POP     H
        POP     D
        RET
        ;
        ;DETERMINES IF ANY KEY IS PUSHED
        ;
KPU:    PUSH    B
        CALL    KRD         ;READ THE KEYBOARD
        MVI     B,$08       ;SET THE LOOP COUNTER
        LXI     H,UDKY      ;ADDRESS OF UNDECODED KEY SCAN
        MVI     A,$FF       ;UNPUSHED KEY CODE
KPU1:   ANA     M           ;LET ANY PUSHED KEY CODE CHANGE A
        INR     L           ;NEXT RAM KEY ROW
        DCR     B           ;LOOP COUNTER
        JNZ     KPU1        ;IF ALL KEY ROWS NOT ANDED WITH A
        CPI     $FF         ;SET FLAG IF ALL KEYS NOT PUSHED
        POP     B
        RET
        ;
        ;READS KEYS AND STORES THEM IN RAM (UDKY)
        ;
KRD:    LXI     H,UDKY      ;ADRS OF UNDECODED KEY SCAN
        MVI     A,$FF       ;BLANK DISPLAY CODE
        OUT     DSP         ;CLEAR DISPLAY
        DCR     A           ;SET A TO 1111 1110 SCAN POINTER
        STC                 ;TO RESET END OF SCAN LOOP FLAG
KRD1:   OUT     SCAN        ;SCAN ONE KEY ROW
        MOV     B,A         ;SAVE SCAN POINTER
        IN      KEY         ;INPUT A KEY ROW
        MOV     M,A         ;STORE IT IN RAM
        MOV     A,B         ;RESTORE SCAN POINTER
        INR     L           ;POINT TO NEXT RAM ADRS
        RAL                 ;MOVE SCAN POINTER TO NEXT KEY ROW
        JC      KRD1        ;IF LAW KEY ROW NOT SCANNED
        RET
        ;
        ;KEY INPUT DECODE TABLE (HDWR STEP IS F7)
        ;
KIT:    .DB     $86         ;INSTR STEP     KEY CODE
        .DB     $85         ;FETCH PC       KEY CODE
        .DB     $00         ;(UNDEFINED)    KEY CODE
        .DB     $84         ;RUN            KEY CODE
        .DB     $80         ;FETCH REG      KEY CODE
        .DB     $82         ;FETCH ADRS     KEY CODE
        .DB     $00         ;    0          KEY CODE
        .DB     $83         ;STORE/INCR     KEY CODE
        .DB     $81         ;DECR           KEY CODE
        .DB     $01         ;    1          KEY CODE
        .DB     $02         ;    2          KEY CODE
        .DB     $03         ;    3          KEY CODE
        .DB     $04         ;    4          KEY CODE
        .DB     $05         ;    5          KEY CODE
        .DB     $06         ;    6          KEY CODE
        .DB     $07         ;    7          KEY CODE
        .DB     $08         ;    8          KEY CODE
        .DB     $09         ;    9          KEY CODE
        .DB     $0A         ;    A          KEY CODE
        .DB     $0B         ;    B          KEY CODE
        .DB     $0C         ;    C          KEY CODE
        .DB     $0D         ;    D          KEY CODE
        .DB     $0E         ;    E          KEY CODE
        .DB     $0F         ;    F          KEY CODE
        ;
        ;SCAN DISPLAY SEGMENTS
        ;
SDS:    PUSH    PSW
        PUSH    H
        PUSH    B
        LXI     H,DDSP5     ;ADRS OF DECODED DISP DIGIT 5
        MVI     B,$20       ;DISP DIGIT 5 SCAN POINTER
SDS1:   XRA     A           ;CLEAR A
        OUT     SCAN        ;TURN DISP DIGIT OFF
        MOV     A,M         ;GET SEGMENT DATA
        OUT     DSP         ;STORE IT IN DSP LATCH
        MOV     A,B         ;GET SCAN DIGIT POINTER
        OUT     SCAN        ;TURN ON DISP DIGIT
        CALL    DELA        ;STRETCH DIGIT 1MS
        DCR     L           ;ADRS OF NEXT DIGIT IN RAM
        RAR                 ;GET SCAN DIGIT POINTER
        MOV     B,A         ;SAVE IT IN B
        JNC     SDS1        ;IF NOT LAST SCANNED DIGIT (LSD)
        CMA                 ;SET A=FF BLANK DISP CODE
        OUT     DSP         ;TURN OFF DSP DIGITS
        POP     B
        POP     H
        POP     PSW
        RET
        ;
        ;DISPLAY CHARACTER DECODER
        ;
DCD:    PUSH    PSW
        PUSH    B
        PUSH    D
        PUSH    H
        LXI     B,DDSP0     ;DECODED DIGIT FIRST ADRS
        LXI     D,UDSP0     ;UNDECODED DIGIT FIRST ADRS
DCD1:   LXI     H,DCC       ;DIPSLAY CODE CONVERTER TABLE ADRS
        LDAX    D           ;GET UNDECODED DATA FOR OFFSET
        PUSH    D           ;SAVE ITS ADRS
        MOV     E,A         ;TABLE OFFSET VALUE TO E
        MVI     D,$00       ;CLEAR D
        DAD     D           ;ADD OFFSET VALUE TO DCC ADRS
        MOV     A,M         ;GET DECODED DATA FROM TABLE ADRS
        STAX    B           ;STORE IT IN DECODED RAM
        POP     D           ;RESTORE UDSPX ADRS
        INR     E           ;POINT TO NEXT UPSP ADRS
        INR     C           ;POINT TO NEXT DDSP ADRS
        JNZ     DCD1        ;IF NOT LAST DIGIT
        LXI     H,DDSP0     ;DECODED DIGIT 0
        LDAX    D           ;UDSP6 DATA MODIFY FLAG
        ANA     A           ;CHECK FOR SET FLAG
        JZ      DCD2        ;IF DATA NOT BEING MODIFIED
        MOV     A,M         ;GET DDSP0 DATA
        ANI     $7F         ;SET ITS DECIMAL POINT DISP BIT
        MOV     M,A         ;STORE IT IN DDSP0
DCD2:   POP     H           ;
        POP     D           ;
        POP     B           ;
        POP     PSW         ;
        CALL    SDS         ;UDPATE DISPLAY
        RET                 ;
        ;
        ;DISPLAY CODE CONVERTER TABLE
        ;
DCC:    .DB     $C0         ;0
        .DB     $F9         ;1
        .DB     $A4         ;2
        .DB     $B0         ;3
        .DB     $99         ;4
        .DB     $92         ;5
        .DB     $82         ;6
        .DB     $F8         ;7
        .DB     $80         ;8
        .DB     $90         ;9
        .DB     $88         ;A
        .DB     $83         ;B
        .DB     $C6         ;C
        .DB     $A1         ;D
        .DB     $86         ;E
        .DB     $8E         ;F
        .DB     $FF         ;BLANK
        .DB     $89         ;H
        .DB     $C7         ;L
        .DB     $E3         ;U SMALL
        .DB     $8C         ;P
        .DB     $A3         ;O
        .DB     $C1         ;U LARGE
        .DB     $F7         ;_
        .DB     $A7         ;C SMALL
        .DB     $CF         ;1 LEFT
        .DB     $00         ;ALL SEGS
        .DB     $AF         ;R SMALL
        .DB     $BF         ;-
        ;
        ;STDM STORES DISP MESSAGE AT DE ADRS IN UDSP RAM
        ;
SDM:    MVI     B,$06       ;LOOP COUNTER FOR 6 DISPLAY DIGITS
SDM1:   LDAX    D           ;DISPLAY CHARACTER
        MOV     M,A         ;STORE IT IN UPSPX IN RAM
        INR     L           ;NEXT UDSP ADRS
        INX     D           ;NEXT MESSAGE TABLE ADRS
        DCR     B           ;LOOP COUNTER
        JNZ     SDM1        ;IF NOT LAST DIGIT
        POP     B           ;
        RET
        ;
        ;DISPLAY MESSAGE TABLES
        ;
DMT:    .DB     $14         ;P
        .DB     $16         ;U
        .DB     $0B         ;B
        .DB     $0A         ;A
        .DB     $12         ;L
        .DB     $13         ;U SMALL
FETCH:  .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $17         ;_
        .DB     $17         ;_
        .DB     $17         ;_
        .DB     $17         ;_
MA:     .DB     $0A         ;A
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
FLG:    .DB     $12         ;L
        .DB     $0F         ;F
        .DB     $10         ;SP
        .DB     $10         ;SP
MB:     .DB     $0B         ;B
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
MC:     .DB     $0C         ;C
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
MD:     .DB     $0D         ;D
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
ME:     .DB     $0E         ;E
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
MH:     .DB     $11         ;H
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
ML:     .DB     $12         ;L
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
SPH:    .DB     $11         ;H
        .DB     $14         ;P
        .DB     $05         ;S
        .DB     $10         ;SP
SPL:    .DB     $12         ;L
        .DB     $14         ;P
        .DB     $05         ;S
        .DB     $10         ;SP
PCH:    .DB     $11         ;H
        .DB     $0C         ;C
        .DB     $14         ;P
        .DB     $10         ;SP
PCL:    .DB     $12         ;L
        .DB     $0C         ;C
        .DB     $14         ;P
        .DB     $10         ;SP
IM:     .DB     $19         ;I
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
ALL:    .DB     $1A         ;ALL
        .DB     $1A         ;ALL
        .DB     $1A         ;ALL
        .DB     $1A         ;ALL
        .DB     $1A         ;ALL
        .DB     $1A         ;ALL
ICX:    .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $0C         ;C
        .DB     $01         ;I
        .DB     $10         ;SP
PPM:    .DB     $1B         ;R SMALL
        .DB     $0E         ;E
        .DB     $14         ;P
        .DB     $05         ;S
BLNKM:  .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
        .DB     $10         ;SP
        ;
        ;BLANK THE DISPLAY
        ;
BLNK:   LXI     D,BLNKM     ;ADRS OF BLNAK MESSAGE TABLE
        RST     3           ;GET MESSAGE
        CALL    DCD         ;SEND TO DISPLAY
        RET
        ;
        ;CONTRL KEY JUMP TABLE
        ;
CHDSS:  CPI     $F7         ;HARDWARE SINGLE STEP PUSHED?
        JZ      HDSS        ;HARDWARE SINGLE STEP ROUTINE
CINSS:  CPI     $86         ;SOFTWARE SINGLE STEP PUSHED?
        JZ      INSS        ;SOFTWARE SINGLE STEP ROUTINE
CRUN:   CPI     $84         ;RUN PUSHED?
        JZ      RUN         ;RUN ROUTINE
CSTRM:  CPI     $83         ;STORE MEMORY PUSHED?
        JZ      STRM        ;STORE MEMORY ROUTINE
CDCRM:  CPI     $81         ;DECREMENT MEMORY PUSHED?
        JZ      DCRM        ;DECREMENT MEMORY ROUTINE
CFETA:  CPI     $82         ;FETCH ADRS PUSHED?
        JZ      FETA        ;FETCH ADRS ROUTINE
CFETP:  CPI     $85         ;FETCH PROGRAM COUNTER PUSHED?
        JZ      TRP7        ;FETCH PROGRAM COUNTER ROUTINE
CFETR:  CPI     $80         ;FETCH REGISTER PUSHED?
        JZ      FETR        ;FETCH REGISTER ROUTINE
        RET                 ;IF NO LEGAL KEY WAS PUSHED
CSTRR:  CPI     $83         ;STORE REGISTER PUSHED?
        JZ      STRR        ;STORE REGISTER ROUTINE
CDCRR:  CPI     $81         ;DECREMENT REGISTER PUSHED?
        JZ      DCRR        ;DECREMENT REGISTER ROUTINE
        JMP     CFETA       ;
        ;
        ;FETCH REGISTER MODE
        ;
FETR:   POP     H           ;UNDO STACK CALL
        LXI     H,MA        ;A REG MESSAGE ADRS
        LXI     B,SAVA      ;ADRS OF USER A REG CONTENTS
FETR1:  DCX     H           ;6-2=4 CHARACTERS IN   REG MESSAGE
        DCX     H           ;
FETR2:  SHLD    RMP         ;STORE IN REGISTER MESSAGE POINTER
        XCHG                ;PUT MESSAGE ADRS IN DE
        RST     3           ;STORE MESSAGE IN RAM
        LDAX    B           ;USERS REG CONTENTS
        MOV     E,A         ;TRANSFER IT TO E
        LXI     H,UDSP1     ;ADRS WHERE DISPLAY REG DATA GOES
        CALL    FETA7       ;FORMAT REG BYTE DATA + STORE IT
        MVI     A,$DB       ;LS BYTE OF SAVIM ADRS
        CMP     C           ;IS REG EXAMINED THE INTRPT MASK?
        JZ      FETR6       ;IF IT IS- HEX KEY INPUT NOT LEGAL
FETR3:  CALL    KIND        ;INPUT KEYS
        CALL    CSTRR       ;LOOK FOR CONTROL
        JNC     FETR3       ;IF NOT A HEX KEY OR NEW CONTROL
        MOV     E,A         ;SAVE 1ST HEX KEY IN E
        INR     L           ;POINT TO UDSP1
        MVI     M,$00       ;CLEAR IT TO DISPLAY A 0
FETR4:  DCR     L           ;POINT BACK TO UDSP0
        MOV     M,E         ;STORE NEW HEX KEY THERE
FETR5:  CALL    DPS         ;TO SET DP AND INPUT KEYS
        CALL    CSTRR       ;LOOK FOR CONTROL
        JNC     FETR5       ;IF NOT A HEX KEY OR NEW CONTROL
        INR     L           ;POINT TO UDSP1
        MOV     D,E         ;PUT OLD NEX CHARACTER INTO D
        MOV     E,A         ;PUT NEW HEX CHARACTER INTO E
        MOV     M,D         ;STORE OLD HEX CHARACTER INTO DSP1
        JMP     FETR4       ;CONTINUE
FETR6:  CALL    KIND        ;INPUT KEYS AND UPDATE DISPLAY
        CALL    CSTRR       ;LOOK FOR CONTROL ONLY
        JMP     FETR6       ;KEEP LOOKING
        ;
        ;DECIMAL POINT SET
        ;
DPS:    MVI     A,$01       ;FLAG SET DATA
        STA     UDSP6       ;SET DATA MODIFY FLAG
        CALL    KIND        ;GET ANOTHER KEY
        PUSH    PSW         ;SAVE KEY CODE
        XRA     A           ;CLEAR A
        STA     UDSP6       ;CLEAR DATA MODIFY FLAG
        POP     PSW         ;RECOVER KEY CODE
        RET
        ;
        ;FETCH MEMORY ADDRESS
        ;
FETA:   POP     D           ;UNDO STACK CALL
FETAR:  LXI     D,FETCH     ;DISPLAY MESSAGE ADRS
        RST     3           ;STORE MESSAGE IN RAM
        MVI     C,$04       ;ADRS DIGIT COUNTER
FETA1:  CALL    KIND        ;READ KEYS AND SCAN DISPLAY
        CALL    CFETA       ;LOOK FOR CONTROL
        JNC     FETA1       ;IF NOT A HEX KEY OR NEW CONTROL
        LXI     H,UDSP6     ;ADRS OF DISPLAY DIGIT 4+2
        MOV     B,A         ;SAVE HEX KEY INPUT
        CPI     $01         ;1 KEY PUSHED?
        JNZ     NCTL        ;IF NOT
        MVI     A,$04       ;MS ADRS POSITION VALUE
        CMP     C           ;ADRS POSITION POINTER
        JNZ     NCTL        ;IF 1 KEY NOT MS ADRS BYTE
        JMP     FETAR       ;WAIT FOR ANOTHER KEY
NCTL:   MOV     A,B         ;RESTORE NON-1 KEY VALUE
        MVI     B,$04       ;DISPLAY POSITION COUNTER
FETA2:  DCR     L           ;POINT TO DISP DIGIT ON RIGHT
        DCR     L           ;POINT TO DISP DIGIT ON RIGHT
        MOV     D,M         ;PUT THIS CHARACTER IN D
        INR     L           ;POINT TO DISP DIGIT ON LEFT
        MOV     M,D         ;STORE THE DIGIT SHIFTED 1 TO LEFT
        DCR     B           ;POSITION COUNTER
        JNZ     FETA2       ;IF NOT DONE ENTERING ADRS
        MOV     M,A         ;KEY CODE TO DISP DIGIT ON LEFT
        DCR     C           ;DIGIT COUNTER
        JNZ     FETA1       ;IF NOT DONE
        CALL    FETA6       ;MERGE LS ADRS BYTE IN DISP TO A
        MOV     C,A         ;STORE MERGED BYTE IN C
        INR     L           ;POINT TO MS ADRS BYTE IN DISP
        CALL    FETA6       ;MERGE IT IN A
        MOV     B,A         ;MERGE IT IN C
FETA3:  LXI     H,UDSP5     ;ADRS OF DISP DIGIT 5
        MOV     E,B         ;PUT MS ADRS BYTE IN E
        CALL    FETA7       ;SEPARATE AND STORE IT IN RAM
        DCR     L           ;POINT TO UDSP3
        MOV     E,C         ;SAVE LS ADRS BYTE
        CALL    FETA7       ;SEPARATE AND STORE IT IN RAM
        DCR     L           ;POINT TO UDSP1
        LDAX    B           ;GET DATA AT FETCH ADRS
        MOV     E,A         ;PUT IT IN E
        CALL    FETA7       ;SEPARATE IT AND DISP IT AS DATA
        ;
        ;MODIFY THE DATA
        ;
        CALL    KIND        ;GET A KEY
        CALL    CHDSS       ;LOOK FOR ANY CONTROL KEY
        MOV     E,A         ;STORE HEX KEY IN E
        MOV     M,A         ;AND UDSP0
        INR     L           ;POINT TO UDSP1
        MVI     M,$00       ;CLEAR IT
FETA4:  DCR     L           ;POINT TO UDSP0
        MOV     M,E         ;STORE LATEST KEY ENTRY THERE
FETA5:  CALL    DPS         ;TO SET DP AND INPUT KEYS
        CALL    CSTRM       ;LOOK FOR CONTROL KEY
        JNC     FETA5       ;IF NOT A VALID KEY
        INR     L           ;POINT TO UDSP1
        MOV     D,E         ;LAST KEY ENTRY
        MOV     E,A         ;NEW KEY ENTRY
        MOV     M,D         ;LAST ENTRY SHIFTED TO UDSP1
        JMP     FETA4       ;UPDATE NEW KEY AND CONTINUE
        ;
        ;MERGES 2 HEX NUMBERS INTO A REG
        ;
FETA6:  MOV     E,M         ;LS HEX CHAR
        INX     H           ;POINT TO MS HEX CHAR
        MOV     A,M         ;MS HEX CHAR
        RLC                 ;MOVE IT TO 4 MS BITS IN A
        RLC                 ;AND CLEAR  4 LS BITS IN A
        RLC                 ;
        RLC                 ;
        ORA     E           ;MERGE MS AND LS HEX CHARS IN A
        RET
        ;
        ;SEPARATES 2 HEX CHARACTERS IN A + STORES IN M
        ;
FETA7:  MOV     A,E         ;PUT MERGED HEX CHARS INTO A
        RRC                 ;MOVE MS HEX CHAR TO 4 LS BITS A
        RRC                 ;
        RRC                 ;
        RRC                 ;
        MVI     D,$0F       ;MASK TO CLEAR 4 MS BITS
        ANA     D           ;DO IT
        MOV     M,A         ;STORE MS HEX CHAR
        DCR     L           ;LS CHAR DESTINATION ADRS
        MOV     A,E         ;GET MERGED HEX CHARS
        ANA     D           ;CLEAR MS HEX CHAR
        MOV     M,A         ;STORE LS HEX CHAR
        RET
        ;
        ;DECREMENTS MEMORY ADRS
        ;
DCRM:   DCX     B           ;POINT TO NEXT LOWER ADRS
        POP     H           ;UNDO STACK CALL
        JMP     FETA3       ;TO FETCH NEW ADRS DATA
        ;
        ;STORES DATA IN MEM AND INCREMENTS ADRS
        ;
STRM:   POP     D           ;UNDO STACK CALL
        CALL    FETA6       ;MERGE 2 HEX DATA VALUES INTO A
        MOV     E,A         ;SAVE IN E
        STAX    B           ;STORE DATA BYTE IN RAM ADRS IN B
        LDAX    B           ;READ IT BACK
        CMP     E           ;IS IT THE SAME? DID IT STORE?
        INX     B           ;POINT TO NEXT RAM ADRS
        JZ      FETA3       ;FETCH NEW ADRS IF LAST STORE OK
        DCX     B           ;ELSE POINT BACK TO LAST RAM ADRS
        PUSH    B           ;SAVE THIS ADRS
        RST     2           ;BEEP A FAIL TO STORE ERROR
        POP     B           ;RESTORE RAM ADRS
        JMP     FETA3       ;AND FETCH IT AGAIN
        ;
        ;RUNS THE PROGRAM STARTING AT ADRS IN DISPLAY
        ;
RUN:    LXI     H,$0132     ;INSTR CODES FOR STA 01XX (RUN)
RUN1:   SHLD    RAML1       ;JUMP LINK IN RAM
        LXI     H,$C310     ;INSTR CODES OF 00 AND JMP XXXX
        SHLD    RAML2       ;JUMP LINK IN RAM
        LXI     SP,SAVIM    ;USER PROG START ADRS LINK+1
        PUSH    B           ;STORE USER START ADRS IN RAM LINK
        LXI     H,SAVSH     ;RAM ADRS OF MSBYTE
        MVI     M,$0B       ;MSBYTE USER SP
        DCX     H           ;RAM ADRS OF LSBYTE USER SP
        MOV     A,M         ;LSBYTE USER SP
        CPI     $40         ;<= 40
        JNC     RUN2        ;IF AVAIL STACK SPACE
        MVI     M,$B0       ;IF NOT, RESET POINTER
RUN2:   LXI     SP,SAVE     ;PREPARE TO RESTORE USER REGS
        POP     D           ;RESTORE D,E
        POP     B           ;RESTORE B,L
        POP     PSW         ;RESOTRE PSW,A
        LXI     SP,SAVSL    ;RAM ADRS OF USER SP
        POP     H           ;PUT SPH,L IN H,L
        SPHL                ;TRANSFER SP VAL TO CPU SP
        LHLD    SAVL        ;RESTORE H,L
        JMP     RAML1       ;LINK TO USER PROGRAM
        ;
        ;INSTRUCTION SINGLE STEP AND RETURN TO MONITOR
        ;
INSS:   LXI     H,$0632     ;INSTR CODES FOR STA 06XX (INSS)
        JMP     RUN1        ;SET LINKS,RESTORE REGS,USER PROG
        ;
        ;HARDWARE SINGLE STEP ONE LINE OF CODE
        ;
HDSS:   LXI     H,$0332     ;INSTR CODES FOR STA 03XX (HDSS)
        JMP     RUN1        ;SET LINKS,RESTORE REGS,USER PROG
        ;
        ;DECREMENTS REGISTER DISPLAYED
        ;
DCRR:   POP     D           ;UNDO STACK CALL
        INX     B           ;POINT TO LAST SAVX REG RAM ADRS
        LHLD    RMP         ;REGISTER MESSAGE POINTER
        DCX     H           ;SUBTRACT 2 FROM IT
        DCX     H           ;
        MVI     A,$E8       ;LS BYTE OF SAVA+1 ADRS IN RAM
        CMP     C           ;SEE IF IT'S IM REG
        JNZ     FETR1       ;FETCH NEW NON-IM REG+DISP IF NOT
        LXI     B,SAVIM     ;ADRS OF IM VALUE IN RAM
        LXI     H,IM        ;ADRS OF IM DISP MESSAGE
        JMP     FETR1       ;FETCH IM REG + DISP IF IT IS IM
        ;
        ;STORES REGISTER DATA AND INCREMENTS
        ;
STRR:   POP     D           ;UNDO STACK CALL
        CALL    FETA6       ;MERGE 2 HEX DATA VALUES IN A
        STAX    B           ;STORE DATA BYTE IN SAVX REG ADRS
        DCX     B           ;POINT TO NEXT SAVX REG ADRS
        LHLD    RMP         ;REGISTER MESSAGE POINTER
        INX     H           ;POINT TO NEXT REG MESSAGE
        INX     H           ;
        INX     H           ;
        INX     H           ;
        MVI     A,$DA       ;LS BYTE OF SAVIM-1 ADRS IN RAM
        CMP     C           ;SEE IF IT'S A REG
        JZ      FETR        ;FETCH A REG + DISP IF IT IS
        JMP     FETR2       ;FETCH NEX REG + DISP IF NOT
        ;
        ;DELAYS APPROX 1MS
        ;
DELA:   PUSH    B
        LXI     B,$0001     ;FIXED 1MS VALUE
        JMP     DEL1        ;START TIMIMG LOOP
        ;
        ;DELAYS APPROX 1MS TIMES VALUE IN BC
        ;
DELB:   PUSH    B
DEL1:   PUSH    PSW
        XRA     A           ;CLEAR A
        PUSH    D           ;
DEL2:   MVI     D,TIME      ;1MS SMALL LOOP TIME CONSTANT
DEL3:   DCR     D           ;1MS LOOP
        JNZ     DEL3        ;IF NOT 1MS WORTH OF COUNTS
        DCX     B           ;LARGE LOOP COUNTER
        CMP     B           ;MS BYTE =0?
        JNZ     DEL2        ;IF NOT, LOOP FOR 1 MORE MS
        CMP     C           ;LS BYTE =0?
        JNZ     DEL2        ;IF NOT, LOOP
        POP     D           ;WHEN DONE
        POP     PSW
        POP     B
        RET
        ;
        ;BEEP PRODUCES A FIXED TONE FREQ. + DURATION
        ;
BEEP2:  MVI     L,$FF       ;DURATION MULTIPLIER
        MVI     H,$00       ;SPEAKER FLAG
        MOV     C,B         ;SET COUNT REG B
        MOV     E,D         ;SET COUNT REG E
        PUSH    H           ;INIT. DONE FLAG
BEEP3:  DCR     C           ;DECR FREQ
        JNZ     BEEP8       ;
        MOV     C,B         ;RESTORE FREQ
        MOV     A,H         ;CHG SPKR FLAG
        CMA                 ;
        ORA     A           ;
        MOV     H,A         ;
        JNZ     BEEP4       ;TEST SPKR FLAG
        MVI     A,$C0       ;TURN SPKR OFF
        SIM                 ;
        JMP     BEEP5       ;
BEEP4:  MVI     A,$40       ;TURN SPKR ON
        SIM                 ;
        CMP     M           ;TIME DELAY INSTR
BEEP5:  POP     PSW         ;GET DONE FLAG
        PUSH    PSW         ;
        ORA     A           ;
        JZ      BEEP6       ;CONTINUE IF NOT DONE
        MOV     A,H         ;RETURN IF SPKR OFF
        ORA     A           ;
        JZ      BEEP7       ;
BEEP6:  DCR     E           ;DURATION CNTR
        JNZ     BEEP9       ;
        MOV     E,D         ;RESTORE DURATION
        DCR     L           ;TIME COUNT
        JNZ     BEEP3       ;
        POP     PSW         ;GET DONE FLAG
        CMA                 ;
        PUSH    PSW         ;SET DONE FLAG
        JMP     BEEP3       ;
BEEP7:  POP     PSW         ;
        RET                 ;
BEEP8:  XTHL                ;DELAY 81 CYCLES
        XTHL                ;
        XTHL                ;
        XTHL                ;
        CMP     M           ;
        JMP     BEEP6       ;
BEEP9:  NOP                 ;DELAY 14 CYCLES
        NOP                 ;
        JMP     BEEP3       ;
        ;
        ;SIGNATURE ANALYSYS TEST LOOP
        ;
SATL1:  DI                  ;TURN OFF INTERRUPTS
        IN      $80         ;PULSE A15 READ START-STOP LINE
        OUT     $80         ;PULSE A15 WRITE START-STOP LINE
        LXI     SP,$0BCE    ;SET TO MONITOR VALUE
        ;
        ;RAM PROTECT TEST
        ;
        OUT     $11         ;SET RAM PROTECT
        STA     $0B11       ;WRITE TO UNPROTECTED RAM
        STA     $0911       ;WRITE TO PROTECTED RAM
        OUT     $10         ;UNPROTECT RAM
        ;
        ;OUTPUT PORT TEST
        ;
        XRA     A           ;CLEAR A
        STC                 ;SET CARRY BIT TO 1 FOR 8 LOOPS
SATL2:  RAL                 ;MOVE 1 BIT TO LEFT
        OUT     LOUT        ;OUTPUT PORT LEDS
        JNC     SATL2       ;IF NOT DONE
        ;
        ;DISPLAY LATCH TEST
        ;
SATL3:  RAL                 ;MOVE 1 BIT TO LEFT
        OUT     DSP         ;OUTPUT DISPLAY SEGMENTS
        JNC     SATL3       ;IF NOT DONE
        ;
        ;SCAN LATCH TEST
        ;
        CMA                 ;SET A TO FF
        CMC                 ;CLEAR CARRY
SATL4:  RAL                 ;MOVE 0 BIT TO LEFT
        OUT     SCAN        ;OUTPUT SCAN LINES
        CALL    DELA        ;STRETCH EACH DISP DIGIT
        JC      SATL4       ;IF NOT DONE
        ;
        ;SPEAKER SERIAL OUT TEST
        ;
        MVI     A,$40       ;SPEAKER ON MASK
        SIM                 ;TURN SPKR ON
        MVI     A,$C0       ;SPKR OFF MASK
        SIM                 ;TURN SPKR OFF
        ;
        ;KEY INPUT TEST
        ;
        XRA     A           ;CLEAR A
        OUT     SCAN        ;ALL SCAN LINES TO LOGIC 0
        IN      KEY         ;RESPOND TO ALL KEYS
        ;
        ;INPUT PORT TEST
        ;
        IN      SIN         ;INPUT THE INPUT SWITCHES
        ;
        ;INTERRUPT KEY TEST
        ;
        LXI     H,BEEP      ;ADRS OF BEEP ROUTINE
        SHLD    $0AFD       ;STORE IT IN INTRPT RAM LINK 6.5
        MVI     A,$C3       ;JUMP OP CODE
        STA     $0AFC       ;STORE IT IN INTRPT RAM LINK 6.5
        MVI     A,$1D       ;INTRPT MASK FOR RST 6.5
        SIM                 ;SET MASK
        EI                  ;ENABLE INTERRUPTS
        JMP     SATL1       ;LOOP BACK TO START OVER AGAIN
        ;
        ;PRESENTS INPUT SWITCH DATA ON OUTPUT LEDS
        ;
ECHO:   LDA     $2000       ;READ INPUT PORT SWITCHES
        STA     $3000       ;WRITE TO OUTPUT PORT LEDS
        JMP     ECHO        ;REPEAT
        ;
        ;AND GATE PROGRAM
        ;
ANDGT:  LDA     $2000       ;READ INPUT PORT
        CPI     $FF
        JZ      ON          ;JUMP IF ALL BITS ARE ONE
        MVI     A,$FF
        STA     $3000       ;TURN OUTPUT LEDS OFF
        JMP     ANDGT
ON:     MVI     A,$FE       ;TURN LED ON
        STA     $3000
        JMP     ANDGT
        ;
        ;CONVEYOR BELT CONTROLLER DEMO PROGRAM
        ;
CONV:   CALL    BLNK        ;BLANK THE DISPLAY
        XRA     A           ;CLEAR A
        STA     UDSP0       ;SET DISPLAY COUNTER
LOOP:   CALL    KIND        ;DISPLAY MESSAGE & READ KEYS
        CPI     $00         ;CHECK FOR "0" KEY
        JNZ     LOOP
        LXI     H,NUM       ;INCREMENT COUNT
        INR     M
        MOV     A,M         ;TEST FOR COUNT=10
        CPI     $0A
        JZ      MOVE
        JMP     LOOP
MOVE:   MVI     A,$7F
        MVI     D,MIN       ;SET LOW FREQ VALUE
MLP:    STA     $3000       ;WRITE DATA TO LEDS
        LXI     B,DTIME     ;WATE DELAY TIME
        PUSH    D
        CALL    DELB
        POP     D
        CALL    TONE        ;GENERATE BEEP
        STC
        RAR                 ;SHIFT PATTERN
        JC      MLP
        STA     $3000       ;TURN OFF LEDS
        JMP     CONV
TONE:   MOV     E,A         ;SAVE A
        PUSH    D
        MOV     B,D
        CALL    BEEP1       ;GENERATE BEEP
        POP     D
        MOV     A,D         ;INCREASE FREQUENCY
        SUI     INCR
        MOV     D,A
        MOV     A,E         ;RESTORE A
        RET
NUM     .EQ     $0BF0       ;RAM BUFFER LOCATION
INCR    .EQ     $10         ;FREQ INCREMENT
MIN     .EQ     $F0         ;FEQUENCY MINIMUM
DTIME   .EQ     80          ;TIME BETWEEN SHIFTS
        ;
        ;WELL TEMPERED MICROPROCESSOR
        ;GENERATES PSEUDO RANDOM TONES FROM ROM
        ;
WTM:    LXI     H,$0180     ;SET ROM POINTER TO 0180
WTM1:   MOV     A,M         ;ROM CONTENTS
        ANI     $7E         ;MASK BITS
        MOV     B,A         ;SET BEEP FREQ. REG
        PUSH    H           ;SAVE ADRS POINTER
        CALL    BEEP1       ;GENERATE BEEP
        POP     H           ;RESTORE ADRS POINTER
        LXI     B,$0050     ;SET DELAY REG
        CALL    DELB        ;PAUSE
        INX     H           ;NEXT ADRS OF ROM
        MVI     A,$03       ;LAST ADRS OF LOOP
        CMP     H           ;LAST ADRS
        JZ      WTM         ;IF LAST ADRS
        JMP     WTM1        ;IF NOT LAST ADRS
        ;
        ;SQUIRREL  FEEDBACK SHIFT REGISTER DISPLAY
        ;
SQRL:   CALL    BLNK        ;CLEAR THE DISPLAY
        XRA     A           ;CLEAR A AND CARRY
        MVI     B,$01       ;SEED
SQRL1:  RAL                 ;SHIFT A  A7 TO CARRY
        MOV     D,A         ;SAVE IT
        MOV     A,B         ;GET B FSR REGISTER
        RAR                 ;SHIFT A7 INTO B7
        MOV     C,A         ;SAVE IT
        XRA     B           ;XOR B0 AND B1
        ANI     $01         ;SET B7 TO B1 TO 0
        ORA     D           ;INSERT B0 XOR B1 IN A0
        MOV     B,C         ;RESTORE NEW B
        LXI     H,DDSP2     ;ADRS OF DECODED DISPALY D2
        PUSH    PSW         ;SAVE A FSR REG
        RRC                 ;GET DIGIT 2 BITS IN POSITION
        RRC                 ;
        CALL    SQRL3       ;FORMAT AND STORE DIGITS 2,3
        INR     L           ;ADRS DIGIT 4
        MOV     A,B         ;GET B FSR REGISTER
        RLC                 ;GET DIGIT 4 BITS IN POSITION
        CALL    SQRL3       ;FORMAT AND STORE IN DIGITS 4,5
        MVI     C,$0F       ;DISPLAY TIMER SEGMENTS
SQRL2:  CALL    SDS         ;DISPLAY SEGMENTS
        DCR     C           ;DCR TIMER
        JNZ     SQRL2       ;IF TIME NOT UP
        POP     PSW         ;RESTORE A FSR REGISTER
        JMP     SQRL1       ;DO IT AGAIN
SQRL3:  MOV     C,A         ;SAVE SHIFTED VALUE
        ORI     $F0         ;BLANK E,F,G,DP SEGS
        MOV     M,A         ;STORE IN DIG 2 OR 4
        MOV     A,C         ;RECALL SHIFTED VALUE
        INR     L           ;ADRS OF DIG 3,5
        RLC                 ;GET A SEG IN D0
        ANI     $01         ;CLEAR D7-D1
        MOV     D,A         ;SAVE A SEG
        MOV     A,C         ;RECALL SHIFTED VALUE
        RRC                 ;MOVE A,F,E,D TO D6-D3
        ANI     $38         ;CLEAR D7-D6,D2-D0
        ORA     D           ;INSERT A SEG IN D0
        ORI     $C6         ;BLANK B,C,H,DP SEGS
        MOV     M,A         ;STORE DIG 3 OR 5
        RET
        ;
        ;ORGAN  GENERATES TONES FROM KEYBOARD
        ;
ORGAN:  MVI     D,$40       ;INITIALIZE SPKR FLAG
ORGAN1: CALL    KRD         ;READ KEYS
        CALL    CODE        ;DECODE KEYS & LOK-UP DELAY VALUE
        ORA     A           ;CHECK FOR NO KEY
        JZ      ORGAN1
        CALL    DLY         ;TIME DELAY
        CALL    SPKR        ;CHANGE SPEAKER STATE
        JMP     ORGAN1      ;REPEAT
        ;
        ;DELAY ROUTINE
        ;
DLY:    DCR     A           ;DECREMENT A UNTIL ZERO
        NOP
        NOP
        JNZ     DLY
        RET
        ;
        ;SPKR ROUTINE TO CHANGE SPEAKER STATE
        ;
SPKR:   MOV     A,D         ;GET SPKR FLAG
        XRI     $80         ;COMPLEMENT BIT 7
        MOV     D,A         ;SAVE FLAG
        SIM                 ;OUTPUT TO SPKR
        RET
        ;
        ;CODE ROUTINE DETERMINES WHICH KEY IS
        ; PRESSED AND LOOKS UP DELAY VALUE
        ;
CODE:   MVI     B,$07       ;INITIALIZE ROW COUNT
        LXI     H,$0BEF     ;INITIALIZE DATA ADDRESS
READ:   MOV     A,M         ;GET KEY DATA
        CMA
        ORA     A           ;ANY KEY PRESSED?
        JZ      NOKEY
        CPI     $04         ;DATA=100?
        JNZ     SHIFT       ;IF YES CHANGE TO 011
        DCR     A
SHIFT:  MOV     C,A         ;SAVE KEY DATA
        MOV     A,B         ;SHIFT ROW COUNT
        RLC
        RLC
        ORA     C           ;COMBINE ROW COUNT & DATA
        LXI     H,TABLE-9   ;SET LOOK-UP ADDRESS
        ADD     L
        MOV     L,A
        MOV     A,M         ;GET DELAY VALUE
        RET
NOKEY:  DCR     B           ;NO KEY PRESSED-GO TO NEXT ROW
        DCX     H
        MOV     A,B         ;DONE?
        CPI     $01
        JNZ     READ        ;IF NOT, READ NEXT ROW
        XRA     A           ;NO KEY - SET DELAY TO 0
        RET
        ;
        ;LOOK-UP TABEL FOR ORGAN DELAY VALUES
        ;
TABLE:  .DB     $E6         ;E3
        .DB     $00
        .DB     $00
        .DB     $00
        .DB     $DA         ;F3
        .DB     $BD         ;G3
        .DB     $A3         ;A3
        .DB     $00
        .DB     $8F         ;B3
        .DB     $85         ;C4
        .DB     $72         ;D4
        .DB     $00
        .DB     $64         ;E4
        .DB     $5C         ;F4
        .DB     $4D         ;G4
        .DB     $00
        .DB     $43         ;A4
        .DB     $38         ;B4
        .DB     $33         ;C5
        .DB     $00
        .DB     $2D         ;D5
        .DB     $24         ;E5
        .DB     $20         ;F5
        ;
        ;ROCKET BLAST-OFF DEMO PROGRAM
        ;
ROCT:   MVI     A,$AA       ;ALL AMBER LED MASK
        OUT     LOUT        ;TURN ON AMBER LEDS
        LXI     D,ROCM      ;ROCKET DISPLAY MESSAGE
        RST     3           ;STORE MESSAGE IN RAM
ROCT1:  MVI     B,$80       ;1 SECOND DELAY LOOP COUNTER
ROCT2:  CALL    DCD         ;UPDATE DISPLAY
        DCR     B           ;COUNTER
        JNZ     ROCT2       ;REPEAT IF <1 SECOND
        RST     2           ;BEEP
        LXI     H,UDSP0     ;COUNT DOWN SECONDS DIGIT
        DCR     M           ;INCREMENT IT
        JNZ     ROCT1       ;IF NOT LAST COUNT (0 SECONDS)
        MVI     B,$00       ;START BLAST-OFF FREQUENCY
        MVI     D,$02       ;START BLAST-OFF DURATION
ROCT3:  MVI     A,$E7       ;LED PATTERN
        CALL    ROCT5       ;SEQUENCE
        MVI     A,$DB       ;LED PATTERN
        CALL    ROCT5       ;SEQUENCE
        MVI     A,$BD       ;LED PATTERN
        CALL    ROCT5       ;SEQUENCE
        MVI     A,$7E       ;LED PATTERN
        CALL    ROCT5       ;SEQUENCE
        JNZ     ROCT3       ;REPEATE IF B70, FREQ <MAX
        XRA     A           ;CLEAR A
        CMA                 ;SET A TO FF
        OUT     LOUT        ;TURN OFF ALL LEDS
        LXI     B,$0500     ;1 SECOND DELAY VALUE
        CALL    DELB        ;FOR 1 SECOND PAUSE
        MVI     A,$03       ;NOTE COUNTER
ROCT4:  MVI     B,$34       ;1ST NOTE FREQ
        PUSH    PSW         ;SAVE NOTE COUNT
        CALL    BEEP1       ;PLAY NOTE
        POP     PSW         ;RESTORE NOTE COUNT
        LXI     B,$0080     ;PAUSE VALUE
        CALL    DELB        ;PAUSE BETWEEN NOTES
        DCR     A           ;NOTE COUNTER
        JNZ     ROCT4       ;IF NOT LAST OF 3 FIRST NOTES
        MVI     B,$85       ;LAST NOTE FREQ
        MVI     D,$40       ;LAST NOTE DURATION
        CALL    BEEP2       ;PLAY LAST NOTE
        RST     1           ;RETURN TO MONITOR
        JMP     ROCT        ;RUN PROGRAM AGAIN
ROCT5:  OUT     LOUT        ;UPDATE LEDS
        CALL    BEEP2       ;BEEP
        DCR     B           ;INCREASE FREQ BY 1
        RET
ROCM:   .DB     $09         ;9
        .DB     $1C         ;-
        .DB     $18         ;SMALL C
        .DB     $15         ;SMALL O
        .DB     $1B         ;SMALL R
        .DB     $10         ;SPACE
        ;
        ;STOPWATCH
        ;
STW:    LXI     D,STWM      ;ADRS OF DISPLAY MESSAGE
        RST     3           ;ZERO DISPLAY
        LXI     D,$00FF     ;RUN AND 3-KEY STATUS
STW1:   XRA     A           ;CLEAR A
        STA     UDSP6       ;TURN OFF DECIMAL POINT FLAG
        CALL    DCD         ;UPDATE DISPLAY
        MVI     B,$F5       ;DELAY CONSTANT
STWL:   DCR     B           ;DELAY COUNTER
        DAD     H           ;DELAY INSTRUCTION
        JNZ     STWL        ;IF NOT DONE
        MVI     A,$FB       ;0-KEY SCAN DATA
        OUT     SCAN        ;0-KEY ROW
        IN      KEY         ;INPUT
        CPI     $FE         ;CHECK FOR 0-KEY
        JZ      STW         ;IF PUSHED
        MVI     A,$F7       ;3-KEY SCAN DATA
        OUT     SCAN        ;3-KEY ROW
        IN      KEY         ;INPUT
        CPI     $FB         ;CHECK FOR 3-KEY
        JNZ     STW6        ;IF NOT PUSHED
        CMP     E           ;WAS IT PUSHED BEFORE?
        JZ      STW2        ;IF IT WAS
        MOV     E,A         ;PUSHED STATUS CODE
        INR     D           ;CHANGE RUN MODE START/STOP
STW2:   MOV     A,D         ;CURRENT RUN MODE
        RAR                 ;FLAG MODE BIT TO CARRY
        JNC     STW1        ;IF IN STOP MODE
        LXI     H,UDSP0     ;.01 SEC MEM LOCATION
STW3:   INR     M           ;INCREMENT DIGIT COUNT
        MOV     A,M         ;LOAD DIGIT IN A
        CPI     $0A         ;OVERFLOW
        JNZ     STW5        ;IF DIGIT 9 OR LESS
        MVI     M,$00       ;SET DIGIT TO 0
STW4:   INR     L           ;NEXT HIGHT DIGIT ADRS
        JMP     STW3        ;REPEAT SEQUENCE ON THIS DIGIT
STW5:   LXI     H,UDSP3     ;10 SEC MEM LOCATION
        MOV     A,M         ;LOAD DIGIT IN A
        CPI     $06         ;OVERFLOW
        JNZ     STW1        ;IF DIGIT 5 OR LESS
        MVI     M,$00       ;SET DIGIT TO 0
        INR     L           ;MIM DIGIT ADRS
        JMP     STW4        ;REPEAT SEQUENCE FOR MIN DIGIT
STW6:   MVI     E,$FF       ;3-KEY NOT PUSHED CODE
        JMP     STW2        ;CONTINUE IN CURRENT RUN MODE
STWM:   .DB     $00         ;ZERO DISPLAY MESSAGE TABLE
        .DB     $00
        .DB     $00
        .DB     $00
        .DB     $10
        .DB     $00
        ;
        ;SNAKE PADDLE GAME
        ;
SNAKE:  LXI     H,$FF00     ;INITIALIZE SCORE DISPLAY
        MVI     B,$F7       ;RIGHT PLAYER CODE
        PUSH    H           ;SAVE SCORE
SERV:   MVI     A,$40       ;SERVE SPEED
        STA     SPEED       ;CURRENT BALL SPEED
        CALL    BLNK        ;CLEAR THE DISPLAY
        POP     H           ;GET SCORE
        MVI     C,$1C       ;CODE FOR '-' CHAR
        MOV     A,B         ;PLAYER CODE
        CPI     RIGHT       ;RT PLAYER LOST POINT?
        MOV     A,C         ;DASH CHAR CODE
        JNZ     LLOSE       ;IF LEFT PLAYER LOST POINT
        STA     UDSP5       ;LEFT SERVE DISPLAY MESSAGE
        INR     H           ;LEFT PLAYER GETS POINT
        MOV     A,H         ;LEFT SCORE
        MVI     B,LEFT      ;LEFT PLAYER GETS SERVE
        JMP     SERV1       ;CONTINUE
LLOSE:  STA     UDSP2       ;RIGHT SERVE DISPLAY MESSAGE
        INR     L           ;RIGHT PLAYER GETS POINT
        MOV     A,L         ;RIGHT SCORE
        MVI     B,RIGHT     ;RIGHT PLAYER GETS SERVE
SERV1:  CPI     $0A         ;LAST POINT
        PUSH    H           ;SAVE SCORE
        SHLD    UDSP0       ;DISPLAY SCORE
        CALL    DCD         ;UDPATE DISPLAY
        JNZ     SERV2       ;IF NOT LAST GAME POINT
ENDGM:  CALL    RSTGM       ;NEW GAME REQUEST?
        CALL    SDS         ;UPDATE DISPLAY
        JNZ     ENDGM       ;WAIT FOR NEW GAME REQUEST
SERV2:  CALL    RSTGM       ;NEW GAME REQUEST?
        JZ      SNAKE       ;IF NEW GAME REQUESTED
        CALL    PADL        ;CHECK PADDLE
        JNZ     SERV2       ;IF NOT PUSHED
RBND:   PUSH    B           ;SAVE HITTING PLAYER CODE
        MOV     A,B         ;HITTING PLAYER CODE
        CPI     LEFT        ;LEFT PLAYER CODE
        LXI     B,LSM       ;LEFT PLAYER MESSAGE POINTER
        JZ      RSRV        ;IF LEFT PLAYER WAS HITTER
        LXI     B,RSM       ;RIGHT PLAYER MESSAGE CODE
RSRV:   CALL    PASS        ;START BALL MOVING
        POP     B           ;RESTORE LAST HITTER CODE
        MOV     A,B         ;HITTING PLAYER CODE
        CPI     LEFT        ;LEFT PLAYER CODE
        MVI     B,RIGHT     ;RIGHT PLAYER CODE
        JZ      RBND1       ;IF BALL CAME FROM LEFT PLAYER
        MVI     B,LEFT      ;LEFT PLAYER NEXT HITTER
RBND1:  CALL    PLAY        ;CHECK PADDLE
        MOV     A,D         ;POINT LOSS REGISTER
        CPI     $FF         ;POINT LOSS CODE
        JNZ     RBND        ;IF NO LOST POINT, REVERSE BALL
        MVI     C,LOSTN     ;LOSE POINT TRILL CODE
        CALL    TRIL        ;PLAY TRILL
        JMP     SERV        ;NEW SERVE
        ;
        ;PASSES BALL FROM ONE PLAYER TO THE OTHER
        ;
PASS:   CALL    BLNK        ;CLEAR THE DISPLAY
        MVI     H,$0B       ;MSBYTE DISP MEM
        MVI     D,$0E       ;BALL PATTERN LENGTH
PASS1:  LDAX    B           ;BALL POSITION DISPLAY CODE
        MOV     E,A         ;SAVE A
        ANI     $12         ;MASK
        RRC                 ;POSITION
        MOV     L,A         ;SAVE
        RRC                 ;POSITION
        RRC                 ;POSITION
        ORA     L           ;MASK
        ANI     $03         ;MASK
        ADI     $FC         ;OFFSET FOR RAM
        MOV     L,A         ;LSBYTE  DISP MEM
        MOV     A,E         ;RESTORE MESSAGE
        ORI     $92         ;SET DP,E,B, SEGS OFF
        MOV     M,A         ;SEND TO UDSPX
        CALL    TIMER       ;DISPLAY IT
        INX     B           ;NEXT MESSAGE
        DCR     D           ;MESSAGE COUNTER
        JNZ     PASS1       ;IF LAST BALL POSITION
        RET
        ;
        ;PLAY ROUTINE WHEN PASS IS COMPLETE
        ;
PLAY:   MVI     D,PNTLS     ;POINT LOSE CODE
        CALL    PADL        ;CHECK PADDLE
        RZ                  ;IF PUSHED TOO SOON
        LDA     SPEED       ;PRESENT BALL SPEED
        MOV     E,A         ;SAVE IT
        MOV     D,A         ;SET REACTION SPEED COUNTER VALUE
        RRC                 ;HALVE BALL SPEED/ TIME
        MOV     C,A         ;SAVE IT
PLAY1:  MOV     A,D         ;RESTORE COUNTER VALUE
        DCR     A           ;COUNTER
        CMP     C           ;HALF TIME
        JZ      FSTR        ;IF PADL NUT PUSHED BY THIS TIME
        MOV     D,A         ;SAVE COUNT
        CALL    PADL        ;CHECK PADDLE
        JNZ     PLAY1       ;IF NOT PUSHED
        MVI     C,SLOTN     ;SLOWER TRILL CODE
        CALL    TRIL        ;PLAY TRILL
        MOV     A,E         ;ORIGINAL BALL SPEED
        CPI     $40         ;SLOWEST SPEED
        RZ                  ;IF ALREADY AT SLOWEST SPEED
        RLC                 ;HALVE BALL SPEED
        STA     SPEED       ;STORE IT
        RET
        ;
        ;FASTER INCREASES RETURN SPEED
        ;
FSTR:   MOV     A,D         ;RESTORE COUNTER VALUE
        MVI     D,PNTLS     ;LOSE SIGNAL CODE
        DCR     A           ;COUNTER
        RZ                  ;IF PADDLE NOT PUSHED IN TIME
        MOV     D,A         ;SAVE A
        CALL    PADL        ;CHECK PADDLE
        JNZ     FSTR        ;IF NOT PUSHED
        MVI     C,FSTTN     ;FASTER SIGNAL CODE
        CALL    TRIL        ;PLAY TRILL
        MOV     A,E         ;ORIGINAL BALL SPEED
        RRC                 ;DOUBLE BALL SPEED
        STA     SPEED       ;STORE IT
        RET
        ;
        ;RESET GAME BUTTON PUSHED ?
        ;
RSTGM:  MVI     A,$FB       ;0 KEY INPUT CODE
        OUT     SCAN        ;SET SCAN LATCH
        IN      KEY         ;INPUT KEYS
        CPI     $FE         ;0 KEY INPUT CODE
        RET
        ;
        ;PADDLE PUSHED?
        ;
PADL:   CALL    SDS         ;UPDATE DISPLAY
        MOV     A,B         ;PADDLE KEY SCAN MASK
        OUT     SCAN        ;SET SCAN LATCH
        IN      KEY         ;INPUT KEYS
        CPI     $FB         ;ACCEPTABLE KEY INPUT CODE
        RET
        ;
        ;TIME CONTROLS BALL SPEED
        ;
TIMER:  LDA     SPEED       ;PRESENT BALL SPEED
TIME1:  CALL    SDS         ;UPDATE DISPLAY / DELAY
        SBI     $02         ;COUNTER
        JNZ     TIME1       ;IF COUNTER NOT DONE
        RET
        ;
        ;TRILL MAKES SPEAKER SOUNDS
        ;
TRIL:   PUSH    D           ;
        PUSH    B           ;
        MVI     B,$06       ;START FREQ
        MVI     D,$01       ;START DURATION
TRIL1:  PUSH    B           ;SAVE START FREQ
        CALL    BEEP2       ;TONE
        POP     B           ;START FREQ
        INR     B           ;DECREASE FREQ
        MOV     A,C         ;TRILL CODE
        CPI     FSTTN       ;FASTER CODE
        JNZ     TRIL2       ;IF NOT
        DCR     B           ;RESTORE FREQ
        DCR     B           ;INCREASE FREQ
TRIL2:  CMP     B           ;LAST BEEP
        JNZ     TRIL1       ;IF NOT DONE
        POP     B           ;
        POP     D           ;
        RET
        ;
        ;LEFT SERVE MESSAGE TABLE
        ;
LSM:    .DB     $F7         ;DISPLAY SEGMENT CODES
        .DB     $F5
        .DB     $E7
        .DB     $E5
        .DB     $E1
        .DB     $A1
        .DB     $A7
        .DB     $B5
        .DB     $B7
        .DB     $97
        .DB     $96
        .DB     $B4
        .DB     $A6
        .DB     $A0
        ;
        ;RIGHT SERVE MESSAGE TABLE
        ;
RSM:    .DB     $EC         ;DISPLAY SEGMENT CODES
        .DB     $EE
        .DB     $FC
        .DB     $FE
        .DB     $DE
        .DB     $9E
        .DB     $BC
        .DB     $AE
        .DB     $AC
        .DB     $A8
        .DB     $A0
        .DB     $A6
        .DB     $B4
        .DB     $96
SPEED   .EQ     $0B00
PNTLS   .EQ     $FF
LEFT    .EQ     $FB
RIGHT   .EQ     $F7
LOSTN   .EQ     $28
SLOTN   .EQ     $0B
FSTTN   .EQ     $01
        ;
        ;LESSON 3  COUNTER PROGRAM
        ;
XSTART: MVI     A,$00       ;SET A REGISTER TO 0
XLOOP:  INR     A           ;INCREMENT A REGISTER
        CPI     $0A         ;COMPARE A REGISTER TO 10
        JZ      XSTART      ;GO TO BEGINNING IF A=10
        JMP     XLOOP       ;INCREMENT AGAIN
        NOP
        NOP
        NOP
        NOP
CHKSM:  .DB     $DE
        ;
        ;EQUATES
        ;
KEY     .EQ     $18         ;KEY INPUT PORT ADRS
SIN     .EQ     $20         ;KEY INPUT PORT ADRS
SCAN    .EQ     $28         ;KEY SCAN PORT ADRS
LOUT    .EQ     $30         ;KEY OUTPUT PORT ADRS
DSP     .EQ     $38         ;KEY DISPLAY PORT ADRS
DIM     .EQ     $0B         ;DEFAULT INTERRUPT MASK
PC      .EQ     $0800       ;DEFAULT PROGRAM COUNTER
USP     .EQ     $0BB0       ;DEFAULT USER STACK POINTER
MSP     .EQ     $0BCE       ;MONITOR STACK POINTER
TIME    .EQ     $8C         ;1MS TIME CONSTANT FOR DELAY LOOP
FREQ    .EQ     $06         ;BEEP DEFAULT FREQUENCY CONSTANT
DURA    .EQ     $04         ;BEEP DEFAULT DURATION CONSTANT
RS4C    .EQ     $0AF0       ;RST4   LINK
RS5C    .EQ     $0AF3       ;RST5   LINK
RS55C   .EQ     $0AF6       ;RST5.5 LINK
RS6C    .EQ     $0AF9       ;RST6   LINK
RS65C   .EQ     $0AFC       ;RST6.5 LINK FOR INTRPT KEY
TPR     .EQ     $0AFF       ;TOP OF PROTECTED RAM
UR      .EQ     $0AEF       ;UPPER RAM BELOW RST LINKS
TSAVSP  .EQ     $0BD1       ;TEMPORARY STACK POINTER SAVE ADRS
TSAVH   .EQ     $0BD3       ;TEMPORARY H,L REG SAVE ADRS
RAML1   .EQ     $0BD5       ;RAM LINK TO USER PROG
RS      .EQ     $0BD6       ;RUN STATUS ADRS
RAML2   .EQ     $0BD7       ;RAM LINK TO USER PROG
SAVIM   .EQ     $0BDB       ;SAVE INTERRUPT MASK ADRS
SAVPC   .EQ     $0BDC       ;SAVE PROGRAM COUNTER ADRS
SAVSL   .EQ     $0BDE       ;SAVE STACK POINTER LOW ADRS
SAVSH   .EQ     $0BDF       ;SAVE STACK POINTER HIGH ADRS
SAVL    .EQ     $0BE0       ;SAVE L REG ADRS
SAVE    .EQ     $0BE2       ;SAVE E REG ADRS
SAVA    .EQ     $0BE7       ;SAVE A REG ADRS
UDKY    .EQ     $0BE8       ;UNDECODED KEY SACN 0
UDSP0   .EQ     $0BF0       ;UNDECODED DISPLAY DIGIT 0 ADRS
UDSP1   .EQ     $0BF1       ;UNDECODED DISPLAY DIGIT 1 ADRS
UDSP2   .EQ     $0BF2       ;UNDECODED DISPLAY DIGIT 2 ADRS
UDSP3   .EQ     $0BF3       ;UNDECODED DISPLAY DIGIT 3 ADRS
UDSP5   .EQ     $0BF5       ;UNDECODED DISPLAY DIGIT 5 ADRS
UDSP6   .EQ     $0BF6       ;UNDECODED DISPLAY DIGIT 6 ADRS
RMP     .EQ     $0BF8       ;REGISTER MESSAGE POINTER
DDSP0   .EQ     $0BFA       ;DECODED DISPLAY DIGIT 0 ADRS
DDSP2   .EQ     $0BFC       ;DECODED DISPLAY DIGIT 2 ADRS
DDSP5   .EQ     $0BFF       ;DECODED DISPLAY DIGIT 5 ADRS