Register parameters

RST 20H, DEFW $1E09

IN:
     HL = 0, not allowed
     HL = 1, not allowed
     HL = 2, 3 byte internal time in ABC (A = high byte, C = low byte)
     HL > 255, HL points to 3 byte internal time (low byte first)
     E = least significant byte of assumed date

OUT, if call successful:
     Fz = 0, if time is inconsistent with assumed date in E(in).

Registers changed after return:
     ..BCDEHL/IXIY same
     AF....../.... different

Notes

The time is used throughout the machine and should only be altered if the user of the machine is fully aware of the fact. Flow sequence:

Divide by 100 (get set seconds).
Read the time in days/seconds.
Store base centiseconds.
Reset the RTC.
X = Days (1 day in seconds)
Z = X + Set seconds
Store new base time

Bugs

Call probably crashes if HL points to segment 3.

Related calls

GN_Gmt, get (read) machine time in internal format
GN_Gtm, convert an ASCII string to a time in internal format
GN_Msc, miscellaneous time operations
GN_Ptm, write internal time as ASCII string
GN_Pmd, Put (set) machine date
GN_Sdo, send date and time to standard output
OS_Dly, delay a given period

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