PORTIBM PC Portable (uses same BIOS as XT) 0010-001F - DMAsee Direct Memory Access CONTROLLER (8237) ON PS/2IBM PS/2, any model MODEL 60 & 80
SeeAlso: PORTIBM PC Portable (uses same BIOS as XT) 0000h-001Fh,PORTIBM PC Portable (uses same BIOS as XT) 0080h-008Fh"DMAsee Direct Memory Access",PORTIBM PC Portable (uses same BIOS as XT) 00C0h-00DFh

0018  -W  extended function register (see #P0007)
001A  -W  extended function execute register


Bitfields for DMAsee Direct Memory Access extended function register:
Bit(s)	Description	(Table P0007)
 7-4	function code (see #P0008)
 3	reserved (0)
 2-0	channel number
	000 channel 0 select
	001 channel 1 select
	010 channel 2 select
	011 channel 3 select
	100 channel 4 select
	101 channel 5 select
	110 channel 6 select
	111 channel 7 select


(Table P0008)
Values for DMAsee Direct Memory Access extended function codes (data go to/from PORTIBM PC Portable (uses same BIOS as XT) 001Ah):
Value	Description		  Parameters  Results
 00h	current address register      -	      CA0,CA1
 02h	write address		      -	      A0,A1,P
 03h	read  address		   A0,A1,P	 -
 04h	write word count register   C0,C1	 -
 05h	read  word count register     -	       C0,C1
 06h	read status register	      -		 S
 07h	mode register		      -		 M
 09h	mask channel		      -		 -
 0Ah	unmask channel		      -		 -
 0Dh	master clear		      -		 -
Note:	CA0/CA1	  LSB/MSB of the current address register
	A0/A1	  LSB/MSB of the base address register
	P	  DMAsee Direct Memory Access page address
	C0/C1	  LSB/MSB of the word count register
	S	  status register value (see #P0001, #P0481)
	M	  mode register value (see #P0005, #P0485)
	first, the extended function register is written, then the extended
	  function register execute register is read/written if the function
	  being executing requires


Bitfields for DMAsee Direct Memory Access extended mode register:
Bit(s)	Description	(Table P0009)
 7	reserved (0)
 6	=0 8-bit transfer
	=1 16-bit transfer
 5-4	reserved (0)
 3	transfer type
	=0 read from memory
	=1 write to memory
 2	=0 disable memory write
	=1 enable  memory write
 1	reserved (0)
 0	address select
	=0 use 0 as base address
	=1 use a value from base address register
Note:	the IBMInternational Busiuness MachinesInternational Busiuness Machines) A hardware, software and other service technology company founded in 1911. PS/2IBM PS/2, any model model 80 technical reference doesn't seem to mention this
	  register's address