MOV
AH,l
;function
is
to set time of
day.
MOV
CX,HIGH_COUNT
;establish the current time.
MOV
DX,
Low_COUNT
INT
lAH
;Set the time.
~
While to read the time
of
day:
MOV
AH,O
;function
is
to read the time
of day.
INT
lAH
;read the timer.
As a general rule, the BIOS routines preserve all registers except
for
AX
and the flags. Other registers are modified on return
only if they are returning a value to the caller. The exact register
usage can be seen in the prologue
of
each BIOS function.
Interrupt Vector Listing
Interrullt
Number
Name
BIOS
Initialization
0
Divide
by
Zero
None
1
Single
Step
None
2
Non
Maskable
NMLlNT
(FOOO:E2C3)
3
Breakpoint
None
4
Overflow
None
5
Print
Screen
PRINLSCREEN
(FOOO:FF54)
6
Unused
7
Unused
8
Time
of
Day
TIMER-INT
(FOOO:FEA5)
9
Keyboard
KLINT
(FOOO:E987)
A
Unused
8259
B
Unused
Interrupt
C
Unused
(Reserved
Communications)
Vectors
D
Unused
E
Diskette
DISK_I
NT
(FOOO:EF57)
F
Unused
(Reserved
Printer)
10
Video
VIDEO_I 0
(FOOO:F065)
11
Equipment
Check
EQUIPMENT
(FOOO:F84D)
12
Memory
MEMORY_SIZE_DETERMINE
(FOOO:F841)
13
Diskette
DISKETTE_I 0
(FOOO:EC59)
14
BIOS
Communications
RS2.3LI 0
(FOOO:E739)
15
Entry
Cassette
CASSETTE_I
0
(FOOO:F859)
16
Points
Keyboard
KEYBOARD_I 0
(FOOO:E82E)
17
Printer
PRINTER_I 0
(FOOO:EF02)
18
Cassette
BASI
C
(F600:0000)
19
Bootstrap
BOOLSTRAP
(FOOO:E6F2)
lA
Time
of
Day
TIME_OF_DAY
(FOOO:FE6E)
lB
User
Supplied
Keyboard
Break
DUMMY_RETURN
(FOOO:FF53)
lC
Routines
Timer
T\ick
,
DUMMY
RETU
RN
(FOOO:
FF53)
lD
Video
Initialization VIDEO_PARMS
(FOOO:FOA4)
BIOS
IE
Diskette
Parameters
DISK_BASE
(FOOO:EFC7)
Parameters
IF
Video
Graphics
Chars
None
3-3
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