ENV-ROD interrupt list
======

ENV-ROD uses INT 22h for interrupts.

AH=00h	EXIT
AH=01h	OPEN
AH=02h	READ
AH=03h	WRITE
AH=04h	LIST
AH=05h	CLOSE
AH=06h	SEEK
AH=07h	CHDIR
AH=08h	UNLINK
AH=09h	MOVE
AH=0Ah	EXEC
AH=0Bh	CREATE
AH=0Ch	MKDIR
AH=0Fh	SET DRIVE
AH=10h	GET CURRENT DIR
AH=11h	GET DRIVE
AH=12h	GET VOLUME NAME
AH=13h	GET TIME
AH=14h	GET DATE
AH=15h	SET TIME
AH=16h	SET DATE

	AH=00h	EXIT

Return value:
none

Exits the program.

	AH=01h	OPEN
AL = Open type (00=read-only, 01=write-only, 02=read-write)
BX = Filename

Return value:
AX=Handler if found
AX=Zero if not found

Opens a file or directory

	AH=02h	READ
BX = Handler
CX = Count
DX = Destination

Return value:
AL=Non-zero if continues
AL=Zero if no longer continues

Reads from file

	AH=03h	WRITE
BX = Handler
CX = Count
DX = Source

Return value:
none

Writes to file

	AH=04h	LIST
BX = Handler
DX = Entry structure

Return value:
none

Lists contents from directory

Ends if first byte of structure is zero.

File structure:
12 bytes	Filename
4 bytes		File size
1 byte		File type (1 if file, 2 if directory)
6 bytes		Last modification date&time
6 bytes		First creation date&time

Date&Time format:
	1 byte: Second
	1 byte: Minute
	1 byte: Hour
	1 byte: Month
	1 byte: Day
	1 byte: Last two digits of year

	AH=05h	CLOSE
BX = Handler

Return value:
none

Closes a file handle.

	AH=06h	SEEK
BX = Handler
CX = Location

Seeks to new location.

	AH=07h	CHDIR
BX = Filename

Changes current directory.

	AH=08h	UNLINK
BX = Filename

Return value:
none

Removes a file or directory.

Warning: The directory needs to be empty
before calling this interrupt.

	AH=09h	MOVE
BX = Source
DX = Destination

Return value:
none

Renames a file/directory or moves
a file/directory to new location.

	AH=0Ah	EXEC
BX = Filename

Executes a file.

	AH=0Bh	CREATE
BX = Filename

Return value:
none

Creates a new file.

	AH=0Ch	MKDIR
BX = Filename

Return value:
none

Creates a new directory.

	AH=0Fh	SET DRIVE
AL = Upper-case drive letter

Return value:
none

Sets current drive letter:
	'A' for master floppy
	'B' for slave floppy

	AH=10h	GET CURRENT DIR
BX = Destination

Return value:
none

Returns filename of current directory.

	AH=11h	GET DRIVE

Return value:
AL = Upper-case drive letter

Returns current drive letter:
	'A' for master floppy
	'B' for slave floppy

	AH=12h	GET VOLUME NAME
DX = Destination

Return value:
none

Returns volume name of current disk.

	AH=13h	GET TIME

Return value:
AL	Second
AH	Minute
BL	Hour

Returns current time.

	AH=14h	GET DATE

Return value:
AL	Month
AH	Day
BL	Year

Returns current date.

	AH=15h	SET TIME
AL = Second
AH = Minute
BL = Hour

Return value:
none

Sets new current time.

	AH=16h	SET DATE
AL = Month
AH = Day
BL = Year

Return value:
none

Sets new current date.