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