Command table, DOS+ ver 2.5

All returned values are in HL, with BA a copy.  Thus 8 bit values are
also returned in A.  Function 0 ignores the pointer at 1,  and can be
used to force system reloading.

"*" marks differences or enhancements from CPM 2.2

 FUNC	NAME			INPUT PARAMS	RETURNED VALUES
    0	Boot			none		none
    1	Console input (echo)	 "		char
    2	Console output		E=char		0
    3	Reader input		none		char
    4	Punch output		E=char		0
    5	List output		E=char		0
*   6	Direct console i/o	E=0FFH		input char
*						0 if no char ready
*				E=0FEH		console status (0/ffh)
*				E=0FDH		input char, wait
*				E=0FCH		look-ahead input char
*		output char	E=000H..0FBH	xy posn (if bios)
    7	Get i/o byte		none		i/o byte (ramlow+03H)
    8	Set i/o byte		E=i/o byte	0
    9	Print string		DE=addr string  0
*  10	Read console buffer	DE=addr buffer	0
   11	Get console status	none		0 if no char ready
	& check for CTL-S pause			ffh if char ready
*  12	DOS+ version number	 "		version num (025H)
						(compatible mode 022h)
*  13	Reset disk system	 "		0 if no A0:$*.* file
						0FFH $*.* file present
   14	Select disk		E=disk number	0
*  15	Open file		DE=addr. FCB	directory code
	(Uses path, can return byte count)
   16	Close file		DE=addr. FCB	directory code
   17	Search for first file	  "		  "
   18	Search for next file	  "		  "
   19	Delete file		  "		error code
   20	Read sequential		  "		read/write code
   21	Write sequential	  "		  "
   22	Make file		  "		directory code
   23	Rename file		  "		error code
   24	Get login vector	none		login vector
   25	Get current disk	  "		current disk
   26	Set DMA address		DE=DMA address	DMA address
   27	Get allocation address	none		addr alloc vector
   28	Write protect disk	  "		0
   29	Get R/O vector		  "		R/O vector
*  30	Set file attributes	DE=addr. FCB	error code
	(can set byte count)
   31	Get address DPB		none		addr. DPB
*  32	Set/get user code	E=0FFH		get user number
				E=0..0feh (set)	e MOD 32
*  33	Read random		DE=addr. FCB	read/write code
*  34	Write random		    "		  "
	(random ops to rcd 262,143)
*  35	Compute file size	    "		error code
*  36	Set random record	    "		0
   37	Reset multiple drive	DE=mask		0
*  40	Write random, zero fill	DE=addr. FCB	read/write code
* 104	Set time   (as CPM3)	DE^= time rcd.	0
* 105	Get time	"	  "		Seconds field (BCD)
* 210	Get info		E=subcommand
				  0		BDOS base address
				  1		DMA setting
				  2		0, flush cons. input
				  3		list status
				  4		punch status (if bios)
				  5		rdr status (if bios)
* 211	Type Decimal		DE=value	write to console,
						suppress lead zeroes.

			Notes

Call 210 subcommand 0 can discriminate between CPM2.2 and DOS+ running
in compatibility mode. CPM returns 0, DOS+ non-zero. in h

All other commands return 0 (unless RSX's provide a value/action)

Directory code	: 00H,01H,02H,03H if no error
		  0FFH	if error
Error code	: 00H	if no error
		  0FFH	if error
Read/write code	: 00H	if no error
		  01H	read  => end of file
			write => directory full
		  02H	disk full
		  03h	cannot close current extent
		  04h	attempt to (random) read unwritten data
		  05h	No available directory space (random write)
		  06h	random record no. out of range

Time Stamps : Access set on file open, modified on close, create on make
(when time stamping enabled and directory formatted).

Archive bit reset only on those extents modified (on file close).
r†