Octagon PC-500, Руководство пользователя

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17-2
Watchdog timer and hardware reset PC-500 user’s manual
Strobe watchdog
Function: fdh
Subfunction: 02h
Purpose: To strobe the watchdog.
Calling registers: AH fdh
AL 02h
DX ffffh
Return registers: None
Comments: This function strobes the watchdog. Once the watch
dog is enabled, it has to be strobed at a period of not
less than 1.6 seconds or until the watchdog is dis-
abled. Otherwise, a system reset will occur.
Programming example:
/* Inline assembly code for Borland C++ 3.1 */
asm {
mov ax,0fd02h
mov dx,0ffffh
int 17h
}
The watchdog timer can also be strobed by reading address 20Ch. This
may be faster than strobing the watchdog timer with an interrupts
function call, for example:
A=INP(20Ch)
Disable watchdog
Function: fdh
Subfunction: 03h
Purpose: To disable the watchdog.
Calling registers: AH fdh
AL 03h
DX ffffh
Return registers: None
Comments: This function disables the watchdog. Once the
watchdog is enabled, it has to be strobed at a period
of not less than 1.6 seconds or until the watchdog is
disabled. Otherwise, a system reset will occur.