User`s guide

BDOS FUNCTION 104: SET DATE AND TIME
Entry Parameters:
Registers C: 68H
DE: DAT Address
Returned Value: none
The Set Date and Time function sets the system internal date and time. The calling
program passes the address of a 4-byte structure containing the date and time speci-
fication in the register pair DE. The format of the date and time (DAT) data structure
is:
byte 0 - 1 Date field
byte 2 Hour field
byte 3 Minute field
The date is represented as a 16-bit integer with day 1 corresponding to January 1,
1978. The time is represented as two bytes: hours and minutes are stored as two
BCD digits.
This function also sets the seconds field of the system date and time to zero.
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BDOS Function Calls CP/M 3 Programmers Guide