The CS/A65 standard library is a set of routines that run in user space and
can be called if the appropriate memory page ($e000-$e7ff) is mapped in
from the system ROM (at $0e000 bus address space).
The zeropage addresses $10-$28 are being used by the library at this
time.

$e7fd	Fgetc	Get a byte from a stream, and wait until the byte is ready,
		using SUSPEND. parameter: stream number in x, returns
		the read byte in a
$e7fa	Fputc	Write a byte on a stream, waiting until it can be delivered
		parameter: stream number in x, data byte in a
$e7f7	Getc	same as Fgetc, for STDIN
$e7f4	Putc	same as Fputc, for STDOUT
$e7f1	Txtout	Write a null terminated string up to 254 byte to STDOUT
		parameter: a/y=address of string (a=lowbyte, y=highbyte)
$e7ee	Hexout	Write a byte to STDOUT in hex. parameter: byte in a
$e7eb	Crlfout	Write carriage return and line feed to STDOUT
$e7e8	Serbrk	reads the status of STDIN and tests if it is E_SEMPTY
		If it is, carry is cleared, otherwise it is set.
$e7e5	Dezbout	writes a byte in decimal to STDOUT
$e7e2	Assign	handles a 10 byte table, that is e.g. used to implement
		the assign command in fsiec
		(carry=0): reads a table entry. parameter: table index in x,
		returns new value in x (a and y are preserved)
		(carry=1, x<0): initialize table with a[i]=i
		(carry=1, 0<=x<10): write new table value
		parameter: table index in x, new value in a
$e7df	Getname	reads a string from memory and tries to interpret it as
		a filename (with possibly leading 'drive:' and paths...)
		leading spaces are ignored. The filename is saved in
		PCBUF+FS_OPEN_NAME. If a drive is given, it is put
		into PCBUF+FS_OPEN_DRV. Otherwise this is set to -1
		parameter: a/y=address of string, returns PCBUF+...
$e7de	Chdir	takes the contents of PCBUF+FS_CMD_* and interprets it as
		a 'change directory' operation, to be done to a given
		path. "." and ".." are interpreted as usual.
		parameter: a/y=address of path, x maximal length of path
$e7d9	Usedir	Takes a path and applies it to a filename in PCBUF.
		If the filename in PCBUF contains a drive or an absolut
		filename is given, nothing is done. Otherwise the 
		the path is put in front of the filename and is put
		into PCBUF again. The path is not changed. "." and ".."
		are not removed here.
		parameter: a/y=address of path, PCBUF+...
		returns new filename in PCBUF+...
$e7d6	Set2name copies a string into PCBUF
		parameter: a/y=address of null terminated string, 
		position the name has to be copied to in PCBUF in x.