374 lines
7.9 KiB
NASM
374 lines
7.9 KiB
NASM
cseg segment para public 'code'
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org 100h
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alarm proc far
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; Memory-resident program to intercept the timer interrupt and display the
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; system time in the upper right-hand corner of the display.
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; This program is run as 'ALARM hh:mm x', where hh:mm is the alarm time and
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; x is '-' to turn the display off. Any other value of x or no value will
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; turn the clock on
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intaddr equ 1ch*4 ; interrupt address
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segaddr equ 62h*4 ; segment address of first copy
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mfactor equ 17478 ; minute conversion factor * 16
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whozat equ 1234h ; signature
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color equ 14h ; color attribute
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assume cs:cseg,ds:cseg,ss:nothing,es:nothing
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jmp p150 ; start-up code
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jumpval dd 0 ; address of prior interrupt
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signature dw whozat ; program signature
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state db 0 ; '-' = off, all else = on
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wait dw 18 ; wait time - 1 second or 18 ticks
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hour dw 0 ; hour of the day
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atime dw 0ffffh ; minutes past midnite for alarm
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acount dw 0 ; alarm beep counter - number of seconds (5)
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atone db 5 ; alarm tone - may be from 1 to 255 - the
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; higher the number, the lower the frequency
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aleng dw 8080h ; alarm length (loop count) may be from 1-FFFF
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dhours dw 0 ; display hours
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db ':'
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dmins dw 0 ; display minutes
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db ':'
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dsecs dw 0 ; display seconds
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db '-'
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ampm db 0 ; 'A' or 'P' for am or pm
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db 'm'
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tstack db 16 dup('stack ') ; temporary stack
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estack db 0 ; end of stack
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holdsp dw 0 ; original sp
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holdss dw 0 ; original ss
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p000: ; interrupt code
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push ax ; save registers
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push ds
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pushf
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push cs
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pop ds ; make ds=cs
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mov ax,wait ; check wait time
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dec ax ; zero?
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jz p010 ; yes - 1 second has elapsed
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mov wait,ax ; not this time
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jmp p080 ; return
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p010: cli ; disable interrupts
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mov ax,ss ; save stack
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mov holdss,ax
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mov holdsp,sp
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mov ax,ds
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mov ss,ax ; point to internal stack
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mov sp,offset estack
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sti ; allow interrupts
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push bx ; save other registers
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push cx
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push dx
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push es
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push si
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push di
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push bp
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mov ax,18 ; reset wait time
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mov wait,ax
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mov al,state ; are we disabled?
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cmp al,'-'
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jnz p015 ; no
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jmp p070
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p015: mov ah,0 ; read time
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int 1ah ; get time of day
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mov ax,dx ; low part
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mov dx,cx ; high part
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mov cl,4
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shl dx,cl ; multiply by 16
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mov bx,ax
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mov cl,12
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shr bx,cl ; isolate top 4 bits of ax
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add dx,bx ; now in upper
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mov cl,4
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shl ax,cl ; multiply by 16
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mov bx,mfactor ; compute minutes
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div bx ; minutes in ax, remainder in dx
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cmp ax,atime ; time to sound the alarm?
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jnz p020 ; no
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call p100 ; yes - beep the speaker twice
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push ax
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mov ax,acount ; get beep count
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dec ax ; down by 1
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mov acount,ax ; save beep count
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cmp ax,0 ; is it zero?
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jnz p018 ; no - keep alarm on
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mov ax,0ffffh ; turn off alarm
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mov atime,ax
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p018: pop ax
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p020: mov dsecs,dx ; save remainder
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mov bx,60 ; compute hours
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xor dx,dx ; zero it
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div bx ; hours in ax, minutes in dx
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mov dmins,dx ; save minutes
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cmp ax,0 ; midnight?
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jnz p030 ; no
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mov ax,12 ; yes
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jmp p040a ; set am
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p030: cmp ax,12 ; before noon?
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jb p040a ; yes - set am
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jz p040p ; noon - set pm
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sub ax,12 ; convert the rest
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p040p: mov bl,'p'
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jmp p040x
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p040a: mov bl,'a'
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p040x: mov ampm,bl
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aam ; fix up hour
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cmp ax,hour ; top of the hour?
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jz p060 ; no
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mov hour,ax
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call p120 ; beep the speaker once
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p060: add ax,3030h ; convert hours to ascii
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xchg ah,al
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mov dhours,ax
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mov ax,dmins ; get minutes
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aam
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add ax,3030h ; convert to ascii
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xchg ah,al
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mov dmins,ax
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mov ax,dsecs ; get seconds (remainder)
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xor dx,dx
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mov bx,60
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mul bx
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mov bx,mfactor
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div bx ; seconds in ax
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aam
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add ax,3030h
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xchg ah,al
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mov dsecs,ax
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xor ax,ax ; check monitor type
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mov es,ax
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mov ax,es:[410h] ; get config byte
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and al,30h ; isolate monitor type
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cmp al,30h ; color?
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mov ax,0b000h ; assume mono
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jz p061 ; its mono
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mov ax,0b800h ; color screen address
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p061: mov dx,es:[463h] ; point to 6845 base port
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add dx,6 ; point to status port
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mov es,ax ; point to monitor
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mov bh,color ; color in bh
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mov si,offset dhours ; point to time
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mov di,138 ; row 1, col 69
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cld
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mov cx,11 ; loop count
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p062: mov bl,[si] ; get next character
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p063: in al,dx ; get crt status
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test al,1 ; is it low?
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jnz p063 ; no - wait
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cli ; no interrupts
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p064: in al,dx ; get crt status
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test al,1 ; is it high?
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jz p064 ; no - wait
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mov ax,bx ; move color & character
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stosw ; move color & character again
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sti ; interrupts back on
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inc si ; point to next character
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loop p062 ; done?
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p070: pop bp ; restore registers
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pop di
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pop si
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pop es
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pop dx
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pop cx
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pop bx
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cli ; no interrupts
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mov ax,holdss
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mov ss,ax
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mov sp,holdsp
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sti ; allow interrupts
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p080: popf
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pop ds
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pop ax
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jmp cs:[jumpval]
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p100 proc near ; beep the speaker twice
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call p120
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push cx
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mov cx,20000
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p105: loop p105 ; wait around
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pop cx
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call p120
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push cx
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mov cx,20000
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p106: loop p106 ; wait around
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pop cx
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call p120
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ret
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p100 endp
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p120 proc near ; beep the speaker once
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push ax
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push cx
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mov al,182
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out 43h,al ; setup for sound
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mov al,0
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out 42h,al ; low part
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mov al,atone ; get alarm tone
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out 42h,al ; high part
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in al,61h
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push ax ; save port value
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or al,3
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out 61h,al ; turn speaker on
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mov cx,aleng ; get loop count
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p125: loop p125 ; wait around
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pop ax ; restore original port value
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out 61h,al ; turn speaker off
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pop cx
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pop ax
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ret
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p120 endp
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p150: ; start of transient code
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mov dx,offset copyr
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call p220 ; print copyright
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mov ax,0
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mov es,ax ; segment 0
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mov di,segaddr+2 ; this program's prior location
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mov ax,es:[di] ; get prior code segment
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mov es,ax ; point to prior program segment
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mov di,offset signature
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mov cx,es:[di] ; is it this program?
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cmp cx,whozat
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jnz p160 ; no - install it
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call p200 ; set state & alarm
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int 20h ; terminate
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p160: mov di,segaddr+2 ; point to int 62h
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mov ax,0
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mov es,ax ; segment 0
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mov ax,ds ; get current ds
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mov es:[di],ax ; set int 62h
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mov si,offset jumpval
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mov di,intaddr ; point to timer interrupt
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mov bx,es:[di] ; get timer ip
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mov ax,es:[di+2] ; and cs
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mov [si],bx ; save prior ip
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mov [si+2],ax ; and cs
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mov bx,offset p000
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mov ax,ds
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cli ; clear interrupts
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mov es:[di],bx ; set new timer interrupt
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mov es:[di+2],ax
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sti ; set interrupts
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push ds
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pop es
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call p200 ; set state & alarm
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mov dx,offset p150 ; last byte of resident portion
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inc dx
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int 27h ; terminate
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p200 proc near ; set state & alarm
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mov si,80h ; point to command line
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mov ax,0
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mov di,0ffffh ; init hours
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mov bh,0
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mov ch,0
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mov dh,0 ; : counter
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mov es:[state],bh ; turn clock on
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mov cl,[si] ; get length
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jcxz p210 ; it's zero
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p203: inc si ; point to next char
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mov bl,[si] ; get it
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cmp bl,'-' ; is it a minus?
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jnz p204 ; no
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mov es:[state],bl ; turn clock off
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push dx
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mov dx,offset msg3 ; print msg
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call p220
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pop dx
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jmp p206
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p204: cmp dh,2 ; seen 2nd colon?
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jz p206 ; yes - ignore seconds
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cmp bl,':' ; colon?
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jnz p205 ; no
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inc dh
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cmp dh,2 ; second colon?
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jz p206 ; yes - ignore seconds
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push cx
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push dx
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mov cx,60
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mul cx ; multiply current ax by 60
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pop dx
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pop cx
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mov di,ax ; save hours
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mov ax,0
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jmp p206
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p205: cmp bl,'0'
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jb p206 ; too low
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cmp bl,'9'
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ja p206 ; too high - can be a problem
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sub bl,'0' ; convert it to binary
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push cx
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push dx
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mov cx,10
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mul cx ; multiply current value by 10
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add ax,bx ; and add latest digit
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pop dx
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pop cx
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p206: loop p203 ; done yet?
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cmp di,0ffffh ; any time to set?
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jz p210 ; no
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add ax,di ; add hours
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cmp ax,24*60
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jb p209 ; ok
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mov dx,offset msg1 ; print error message
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call p220
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jmp p210
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p209: mov es:[atime],ax ; save minutes past midnight
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mov ax,5
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mov es:[acount],ax ; set alarm count
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mov dx,offset msg2 ; print set msg
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call p220
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p210: ret
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p200 endp
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p220 proc near ; print message
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push ax
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mov ah,9
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int 21h
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pop ax
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ret
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p220 endp
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copyr db 'Alarm - Clock',10,13,'$'
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msg1 db 'Invalid time - must be from 00:00 to 23:59',10,13,'$'
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msg2 db 'Resetting alarm time',10,13,'$'
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msg3 db 'Turning clock display off',10,13,'$'
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alarm endp
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cseg ends
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end alarm
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