Assembly Source series of alarm

This is the past DOS era of the compilation of source code, although has passed, but for the study of the assembly is still helpful, assembly language is just a basic programmer language, most people can grasp, not necessarily in-depth research.

CSEG segment para Public ' code '
Org 100h
Alarm proc Far
; Memory-resident to intercept the timer interrupt and display the
; System time in the upper right-hand corner of the display.
; This are 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 would
; Turn the clock on
INTADDR equ 1ch*4; Interrupt Address
SEGADDR equ 62h*4; Segment address of the
Mfactor equ 17478; Minute conversion factor * 16
Whozat equ 1234h; Signature
Color Equ 14h; Color attribute
Assume cs:cseg,ds:cseg,ss:nothing,es:nothing
JMP p150; Start-up code
Jumpval DD 0; Address of Prior interrupt
Signature DW Whozat; Program Signature
State DB 0; '-' = off, any else = on
Wait DW 18; Wait time-1 second or ticks
Hour DW 0; Hour of the day
Atime DW 0ffffh; Minutes past Midnite for alarm
Acount DW 0; Alarm beep Counter-number of seconds (5)
Atone DB 5; Alarm Tone-may is from 1 to 255-the
; Higher the number, the lower the frequency
Aleng DW 8080h; Alarm Length (loop count) May is from 1-FFFF
Dhours 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 dup (' stack '); Temporary stack
Estack DB 0; End of Stack
HOLDSP DW 0; Original SP
HOLDSS DW 0; Original SS
p000:; 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; Return
P010: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 p070
P015: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,ax
P018:pop Ax
P020: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 AM
P030:CMP ax,12; Before noon?
JB p040a; Yes-set am
JZ p040p; Noon-set pm
Sub ax,12; Convert the rest
P040p:mov bl, ' P '
JMP p040x
P040a: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 once
P060: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 Address
P061: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 count
P062:mov Bl,[si]; Get Next character
P063:in AL,DX; Get CRT Status
Test al,1; Is it low?
JNZ p063; No-wait
CLI; No interrupts
P064: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 interrupts
P080:popf
Pop ds
Pop ax
JMP Cs:[jumpval]
P100 proc near; Beep the speaker twice
Call p120
Push CX
MOV cx,20000
P105:loop p105; Wait around
Pop CX
Call p120
Push CX
MOV cx,20000
P106:loop p106; Wait around
Pop CX
Call p120
Ret
P100 ENDP
p120 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 Count
P125:loop p125; Wait around
Pop ax; Restore Original port value
Out 61h,al; Turn speaker off
Pop CX
Pop ax
Ret
P120 ENDP
P150:; 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 the program?
CMP Cx,whozat
JNZ p160; No-install it
Call P200; Set State & Alarm
int 20h; Terminate
P160: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; Terminate
P200 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 zero
P203: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 p206
P204: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 p206
p205: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 CX
P206: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 p210
P209: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 P220
P210:ret
P200 ENDP
p220 proc near; Print message
Push AX
MOV ah,9
int 21h
Pop ax
Ret
P220 ENDP
Copyr db ' Alarm-clock ', 10, 13, ' $ '
MSG1 db ' Invalid Time-must is from 00:00 to 23:59 ', 10, 13, ' $ '
MSG2 DB ' Resetting alarm time ', 10, 13, ' $ '
MSG3 db ' turning clock display off ', 10, 13, ' $ '
Alarm ENDP
Cseg ends
End Alarm