cseg	segment para public 'code'org	100halarm	proc far; Memory-resident program to intercept the timer interrupt and display the; system time in the upper right-hand corner of the display.; This program is run as 'ALARM hh:mm x', where hh:mm is the alarm time and; x is '-' to turn the display off. Any other value of x or no value will; turn the clock onintaddr equ 1ch*4		; interrupt addresssegaddr equ 62h*4		; segment address of first copymfactor equ 17478		; minute conversion factor * 16whozat	equ 1234h		; signaturecolor	equ 14h 		; color attribute	assume cs:cseg,ds:cseg,ss:nothing,es:nothing	jmp p150		; start-up codejumpval dd 0			; address of prior interruptsignature dw whozat		; program signaturestate	db 0			; '-' = off, all else = onwait	dw 18			; wait time - 1 second or 18 tickshour	dw 0			; hour of the dayatime	dw 0ffffh		; minutes past midnite for alarmacount	dw 0			; alarm beep counter - number of seconds (5)atone	db 5			; alarm tone - may be from 1 to 255 - the				; higher the number, the lower the frequencyaleng	dw 8080h		; alarm length (loop count) may be from 1-FFFFdhours	dw 0			; display hours	db ':'dmins	dw 0			; display minutes	db ':'dsecs	dw 0			; display seconds	db '-'ampm	db 0			; 'A' or 'P' for am or pm	db 'm'tstack	db 16 dup('stack   ')   ; temporary stackestack	db 0			; end of stackholdsp	dw 0			; original spholdss	dw 0			; original ssp000:				; interrupt code	push ax 		; save registers	push ds	pushf	push cs	pop ds			; make ds=cs	mov ax,wait		; check wait time	dec ax			; zero?	jz p010 		; yes - 1 second has elapsed	mov wait,ax		; not this time	jmp p080		; returnp010:	cli			; disable interrupts	mov ax,ss		; save stack	mov holdss,ax	mov holdsp,sp	mov ax,ds	mov ss,ax		; point to internal stack	mov sp,offset estack	sti			; allow interrupts	push bx 		; save other registers	push cx	push dx	push es	push si	push di	push bp	mov ax,18		; reset wait time	mov wait,ax	mov al,state		; are we disabled?	cmp al,'-'	jnz p015		; no	jmp p070p015:	mov ah,0		; read time	int 1ah 		; get time of day	mov ax,dx		; low part	mov dx,cx		; high part	mov cl,4	shl dx,cl		; multiply by 16	mov bx,ax	mov cl,12	shr bx,cl		; isolate top 4 bits of ax	add dx,bx		; now in upper	mov cl,4	shl ax,cl		; multiply by 16	mov bx,mfactor		; compute minutes	div bx			; minutes in ax, remainder in dx	cmp ax,atime		; time to sound the alarm?	jnz p020		; no	call p100		; yes - beep the speaker twice	push ax	mov ax,acount		; get beep count	dec ax			; down by 1	mov acount,ax		; save beep count	cmp ax,0		; is it zero?	jnz p018		; no - keep alarm on	mov ax,0ffffh		; turn off alarm	mov atime,axp018:	pop axp020:	mov dsecs,dx		; save remainder	mov bx,60		; compute hours	xor dx,dx		; zero it	div bx			; hours in ax, minutes in dx	mov dmins,dx		; save minutes	cmp ax,0		; midnight?	jnz p030		; no	mov ax,12		; yes	jmp p040a		; set amp030:	cmp ax,12		; before noon?	jb p040a		; yes - set am	jz p040p		; noon - set pm	sub ax,12		; convert the restp040p:	mov bl,'p'	jmp p040xp040a:	mov bl,'a'p040x:	mov ampm,bl	aam			; fix up hour	cmp ax,hour		; top of the hour?	jz p060 		; no	mov hour,ax	call p120		; beep the speaker oncep060:	add ax,3030h		; convert hours to ascii	xchg ah,al	mov dhours,ax	mov ax,dmins		; get minutes	aam	add ax,3030h		; convert to ascii	xchg ah,al	mov dmins,ax	mov ax,dsecs		; get seconds (remainder)	xor dx,dx	mov bx,60	mul bx	mov bx,mfactor	div bx			; seconds in ax	aam	add ax,3030h	xchg ah,al	mov dsecs,ax	xor ax,ax		; check monitor type	mov es,ax	mov ax,es:[410h]	; get config byte	and al,30h		; isolate monitor type	cmp al,30h		; color?	mov ax,0b000h		; assume mono	jz p061 		; its mono	mov ax,0b800h		; color screen addressp061:	mov dx,es:[463h]	; point to 6845 base port	add dx,6		; point to status port	mov es,ax		; point to monitor	mov bh,color		; color in bh	mov si,offset dhours	; point to time	mov di,138		; row 1, col 69	cld	mov cx,11		; loop countp062:	mov bl,[si]		; get next characterp063:	in al,dx		; get crt status	test al,1		; is it low?	jnz p063		; no - wait	cli			; no interruptsp064:	in al,dx		; get crt status	test al,1		; is it high?	jz p064 		; no - wait	mov ax,bx		; move color & character	stosw			; move color & character again	sti			; interrupts back on	inc si			; point to next character	loop p062		; done?p070:	pop bp			; restore registers	pop di	pop si	pop es	pop dx	pop cx	pop bx	cli			; no interrupts	mov ax,holdss	mov ss,ax	mov sp,holdsp	sti			; allow interruptsp080:	popf	pop ds	pop ax	jmp cs:[jumpval]p100	proc near		; beep the speaker twice	call p120	push cx	mov cx,20000p105:	loop p105		; wait around	pop cx	call p120	push cx	mov cx,20000p106:	loop p106		; wait around	pop cx	call p120	retp100	endpp120	proc near		; beep the speaker once	push ax	push cx	mov al,182	out 43h,al		; setup for sound	mov al,0	out 42h,al		; low part	mov al,atone		; get alarm tone	out 42h,al		; high part	in al,61h	push ax 		; save port value	or al,3	out 61h,al		; turn speaker on	mov cx,aleng		; get loop countp125:	loop p125		; wait around	pop ax			; restore original port value	out 61h,al		; turn speaker off	pop cx	pop ax	retp120	endpp150:				; start of transient code	mov dx,offset copyr	call p220		; print copyright	mov ax,0	mov es,ax		; segment 0	mov di,segaddr+2	; this program's prior location	mov ax,es:[di]		; get prior code segment	mov es,ax		; point to prior program segment	mov di,offset signature	mov cx,es:[di]		; is it this program?	cmp cx,whozat	jnz p160		; no - install it	call p200		; set state & alarm	int 20h 		; terminatep160:	mov di,segaddr+2	; point to int 62h	mov ax,0	mov es,ax		; segment 0	mov ax,ds		; get current ds	mov es:[di],ax		; set int 62h	mov si,offset jumpval	mov di,intaddr		; point to timer interrupt	mov bx,es:[di]		; get timer ip	mov ax,es:[di+2]	; and cs	mov [si],bx		; save prior ip	mov [si+2],ax		; and cs	mov bx,offset p000	mov ax,ds	cli			; clear interrupts	mov es:[di],bx		; set new timer interrupt	mov es:[di+2],ax	sti			; set interrupts	push ds	pop es	call p200		; set state & alarm	mov dx,offset p150	; last byte of resident portion	inc dx	int 27h 		; terminatep200	proc near		; set state & alarm	mov si,80h		; point to command line	mov ax,0	mov di,0ffffh		; init hours	mov bh,0	mov ch,0	mov dh,0		; : counter	mov es:[state],bh	; turn clock on	mov cl,[si]		; get length	jcxz p210		; it's zerop203:	inc si			; point to next char	mov bl,[si]		; get it	cmp bl,'-'              ; is it a minus?	jnz p204		; no	mov es:[state],bl	; turn clock off	push dx	mov dx,offset msg3	; print msg	call p220	pop dx	jmp p206p204:	cmp dh,2		; seen 2nd colon?	jz p206 		; yes - ignore seconds	cmp bl,':'              ; colon?	jnz p205		; no	inc dh	cmp dh,2		; second colon?	jz p206 		; yes - ignore seconds	push cx	push dx	mov cx,60	mul cx			; multiply current ax by 60	pop dx	pop cx	mov di,ax		; save hours	mov ax,0	jmp p206p205:	cmp bl,'0'	jb p206 		; too low	cmp bl,'9'	ja p206 		; too high - can be a problem	sub bl,'0'              ; convert it to binary	push cx	push dx	mov cx,10	mul cx			; multiply current value by 10	add ax,bx		; and add latest digit	pop dx	pop cxp206:	loop p203		; done yet?	cmp di,0ffffh		; any time to set?	jz p210 		; no	add ax,di		; add hours	cmp ax,24*60	jb p209 		; ok	mov dx,offset msg1	; print error message	call p220	jmp p210p209:	mov es:[atime],ax	; save minutes past midnight	mov ax,5	mov es:[acount],ax	; set alarm count	mov dx,offset msg2	; print set msg	call p220p210:	retp200	endpp220	proc near		; print message	push ax	mov ah,9	int 21h	pop ax	retp220	endpcopyr	db 'Alarm - Clock',10,13,'$'msg1	db 'Invalid time - must be from 00:00 to 23:59',10,13,'$'msg2	db 'Resetting alarm time',10,13,'$'msg3	db 'Turning clock display off',10,13,'$'alarm	endpcseg	endsend	alarm