Holtek HT-IDE, User Manual

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second db ? ;hold second
minl db ? ;hold minute low byte
minh db ? ;hold minute high byte
hourl db ? ;hold hour low byte
hourh db ? ;hold hour high byte
count1 db ? ;delay counter
mask db ? ;hold mask
disp db ? ;hold display data
;------------------------------------------------------------
code .section at 0 ’code’ ;== program section ==
org 00h ;
jmp start ;
org 04h ;external interrupt subroutine
reti ;for safeguard
org 08h ;timer/event 0 interrupt subroutine
inc second ;1 (unit: 0.5second)
cpl pb ;flash ’dot’(on 0.5s then off 0.5s)
reti ;end ISR
org 0ch ;timer/event 1 interrupt subroutine
reti ;for safeguard
start: ;
clr intc ;initialize registers
clr tmr0c ;to guarantee performance
clr tmr0h ;(interrupts)
clr tmr0l ;
clr tmr1c ;
clr tmr1 ;
set pac ;(ports)
set pbc ;(input mode)
set pcc ;
set pdc ;
main:
clr pac ;(1) ;set port A to output port
mov a,7fh ;set port B to input port
mov pbc,a ;exclude pb.7
clr pb ;(2) ;zero variables
clr pa ;
clr minl ;
clr minh ;
clr hourl ;
clr hourh ;
clr second ;
mov a,05h ;enable timer0
mov intc,a ;
mov a,80h ;set timer0 mode (internal clock)
mov tmr0c,a ;
mov a,0b0h ;(5) ;load timer0 counter (0.5 second)
mov tmr0l,a ;(low byte)
mov a,3ch ;
HT-IDE User’s Guide
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