The Programmer's Guide to TRSDOS Version 6 - Tim Mann's Home ...

Exit:
A Error return code, if any.
Z Set if the operation was successful.
7.6.87 @TIME SVC-19
This SVC will return the time of day in display format (HH:MM:SS). It also will recover a
pointer to the binary time storage which may be useful for those implementing hardware
clocks.
Registers Affected: AF, BC, DE.
Entry:
HL A pointer to the 8-character buffer to receive the time string.
Exit:
DE Returns a pointer to the binary time storage, TIME$. The 3-byte region
contains seconds, minutes, and hours. TIME$-1 stores the 30 Hertz rate
system timer.
7.6.88 @VDCTL SVC-15
This SVC performs various video control functions depending on the function code passed
in register B. It is very useful for handling direct video access. The functions are as
follows:
VIDEO "PEEK"
Registers Affected: AF, BC, DE.
Entry:
B 1; Gets the character at the position identified by HL.
HL Contains the row (0-23) in register H, and column (0-79) in L.
Exit:
A Will be returned with the character at "HL".
Z Set if the operation was successful.
VIDEO "POKE"
Registers Affected: AF, BC, DE.
Entry:
B 2; Puts the character at the position identified by HL.
HL Contains the row (0-23) in register H, and column (0-79) in L.
C Contains the character to put at "HL".
Exit:
Z Set if the operation was successful.
SET CURSOR POSITION
Registers Affected: AF, B, DE.
Entry:
B 3; Moves the cursor to the position identified by HL.
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