IBM-PCとPC/ATに基づくすべてのシステムでは, 同じI/Oポートに配置された DMAハードウェアを持っています. その完全なリストを以下に示します. DMAコントローラ2に割り当てられたポートは, AT以外のデザインでは 未定義になっています.
DMA アドレス および カウントレジスタ
0x00 write Channel 0 starting address 0x00 read Channel 0 current address 0x01 write Channel 0 starting word count 0x01 read Channel 0 remaining word count 0x02 write Channel 1 starting address 0x02 read Channel 1 current address 0x03 write Channel 1 starting word count 0x03 read Channel 1 remaining word count 0x04 write Channel 2 starting address 0x04 read Channel 2 current address 0x05 write Channel 2 starting word count 0x05 read Channel 2 remaining word count 0x06 write Channel 3 starting address 0x06 read Channel 3 current address 0x07 write Channel 3 starting word count 0x07 read Channel 3 remaining word count
DMA コマンドレジスタ
0x08 write Command Register 0x08 read Status Register 0x09 write Request Register 0x09 read - 0x0a write Single Mask Register Bit 0x0a read - 0x0b write Mode Register 0x0b read - 0x0c write Clear LSB/MSB Flip-Flop 0x0c read - 0x0d write Master Clear/Reset 0x0d read Temporary Register (新しいバージョンでは利用不可) 0x0e write Clear Mask Register 0x0e read - 0x0f write Write All Mask Register Bits 0x0f read Read All Mask Register Bits (Intel 82374にのみ存在する)
DMA アドレス および カウントレジスタ
0xc0 write Channel 4 starting address 0xc0 read Channel 4 current address 0xc2 write Channel 4 starting word count 0xc2 read Channel 4 remaining word count 0xc4 write Channel 5 starting address 0xc4 read Channel 5 current address 0xc6 write Channel 5 starting word count 0xc6 read Channel 5 remaining word count 0xc8 write Channel 6 starting address 0xc8 read Channel 6 current address 0xca write Channel 6 starting word count 0xca read Channel 6 remaining word count 0xcc write Channel 7 starting address 0xcc read Channel 7 current address 0xce write Channel 7 starting word count 0xce read Channel 7 remaining word count
DMA コマンドレジスタ
0xd0 write Command Register 0xd0 read Status Register 0xd2 write Request Register 0xd2 read - 0xd4 write Single Mask Register Bit 0xd4 read - 0xd6 write Mode Register 0xd6 read - 0xd8 write Clear LSB/MSB Flip-Flop 0xd8 read - 0xda write Master Clear/Reset 0xda read Temporary Register (Intel 82374には存在しない) 0xdc write Clear Mask Register 0xdc read - 0xde write Write All Mask Register Bits 0xdf read Read All Mask Register Bits (Intel 82374にのみ存在する) 0xdf read Read All Mask Register Bits
0x87 r/w Channel 0 Low byte (23-16) page Register 0x83 r/w Channel 1 Low byte (23-16) page Register 0x81 r/w Channel 2 Low byte (23-16) page Register 0x82 r/w Channel 3 Low byte (23-16) page Register 0x8b r/w Channel 5 Low byte (23-16) page Register 0x89 r/w Channel 6 Low byte (23-16) page Register 0x8a r/w Channel 7 Low byte (23-16) page Register 0x8f r/w Low byte page Refresh
Intel 82374 EISA System Component (ESC)は1996年の初めに発表されました. この中 には機能的には8237のスーパーセットであり, 1つのパッケージの中にその他の PC互換機のコアとなる周辺コンポーネントをも含んだDMAコントローラも含まれています. このチップはEISAとPCI両方のプラットホームをターゲットにしたものであり, scatter-gather I/O やリングバッファを始めとして, システムDMAをして32ビットの アドレス空間全体に直接アクセスする能力も提供しています.
これらの機能を使用する場合でも, 過去16年間のPC互換機で利用されてきた 同等機能を提供するコードも含めておく必要があります. 互換性の問題から, 82374の レジスタの一部は, 従来の8237のレジスタをプログラムした後に, 転送の度にプログラムされる必要があります. 8237のレジスタに書き込みを行うとき, ソフトウェアの下位互換性のために, 82374で追加された一部のレジスタの内容が 強制的に0にクリアされるからです.
0x401 r/w Channel 0 High byte (bits 23-16) word count 0x403 r/w Channel 1 High byte (bits 23-16) word count 0x405 r/w Channel 2 High byte (bits 23-16) word count 0x407 r/w Channel 3 High byte (bits 23-16) word count 0x4c6 r/w Channel 5 High byte (bits 23-16) word count 0x4ca r/w Channel 6 High byte (bits 23-16) word count 0x4ce r/w Channel 7 High byte (bits 23-16) word count 0x487 r/w Channel 0 High byte (bits 31-24) page Register 0x483 r/w Channel 1 High byte (bits 31-24) page Register 0x481 r/w Channel 2 High byte (bits 31-24) page Register 0x482 r/w Channel 3 High byte (bits 31-24) page Register 0x48b r/w Channel 5 High byte (bits 31-24) page Register 0x489 r/w Channel 6 High byte (bits 31-24) page Register 0x48a r/w Channel 6 High byte (bits 31-24) page Register 0x48f r/w High byte page Refresh 0x4e0 r/w Channel 0 Stop Register (bits 7-2) 0x4e1 r/w Channel 0 Stop Register (bits 15-8) 0x4e2 r/w Channel 0 Stop Register (bits 23-16) 0x4e4 r/w Channel 1 Stop Register (bits 7-2) 0x4e5 r/w Channel 1 Stop Register (bits 15-8) 0x4e6 r/w Channel 1 Stop Register (bits 23-16) 0x4e8 r/w Channel 2 Stop Register (bits 7-2) 0x4e9 r/w Channel 2 Stop Register (bits 15-8) 0x4ea r/w Channel 2 Stop Register (bits 23-16) 0x4ec r/w Channel 3 Stop Register (bits 7-2) 0x4ed r/w Channel 3 Stop Register (bits 15-8) 0x4ee r/w Channel 3 Stop Register (bits 23-16) 0x4f4 r/w Channel 5 Stop Register (bits 7-2) 0x4f5 r/w Channel 5 Stop Register (bits 15-8) 0x4f6 r/w Channel 5 Stop Register (bits 23-16) 0x4f8 r/w Channel 6 Stop Register (bits 7-2) 0x4f9 r/w Channel 6 Stop Register (bits 15-8) 0x4fa r/w Channel 6 Stop Register (bits 23-16) 0x4fc r/w Channel 7 Stop Register (bits 7-2) 0x4fd r/w Channel 7 Stop Register (bits 15-8) 0x4fe r/w Channel 7 Stop Register (bits 23-16) 0x40a write Channels 0-3 Chaining Mode Register 0x40a read Channel Interrupt Status Register 0x4d4 write Channels 4-7 Chaining Mode Register 0x4d4 read Chaining Mode Status 0x40c read Chain Buffer Expiration Control Register 0x410 write Channel 0 Scatter-Gather Command Register 0x411 write Channel 1 Scatter-Gather Command Register 0x412 write Channel 2 Scatter-Gather Command Register 0x413 write Channel 3 Scatter-Gather Command Register 0x415 write Channel 5 Scatter-Gather Command Register 0x416 write Channel 6 Scatter-Gather Command Register 0x417 write Channel 7 Scatter-Gather Command Register 0x418 read Channel 0 Scatter-Gather Status Register 0x419 read Channel 1 Scatter-Gather Status Register 0x41a read Channel 2 Scatter-Gather Status Register 0x41b read Channel 3 Scatter-Gather Status Register 0x41d read Channel 5 Scatter-Gather Status Register 0x41e read Channel 5 Scatter-Gather Status Register 0x41f read Channel 7 Scatter-Gather Status Register 0x420-0x423 r/w Channel 0 Scatter-Gather Descriptor Table Pointer Register 0x424-0x427 r/w Channel 1 Scatter-Gather Descriptor Table Pointer Register 0x428-0x42b r/w Channel 2 Scatter-Gather Descriptor Table Pointer Register 0x42c-0x42f r/w Channel 3 Scatter-Gather Descriptor Table Pointer Register 0x434-0x437 r/w Channel 5 Scatter-Gather Descriptor Table Pointer Register 0x438-0x43b r/w Channel 6 Scatter-Gather Descriptor Table Pointer Register 0x43c-0x43f r/w Channel 7 Scatter-Gather Descriptor Table Pointer Register