Intel 386 Table 4-2. Peripheral Register Addresses (Sheet 1 of 6)

4-15
SYSTEM REGISTER ORGANIZATION
4.7 PERIPHERAL REGISTER ADDRESSES
Table 4-2 lists the addresses and names of all user-accessible peripheral registers. I/O Registers
can be accessed as bytes or words. Word accesses to byte registers result in two sequential 8-bit
I/O transfers. The default (reset) value of e ach register is shown in the Reset Value column. An X
in this column signifies that the register bits are undefined. Some address values do not access
registers, but are decoded to provide a logic control signal. These addresses are listed as Not a
regist er in the Reset column.
Table 4-2. Peripheral Register Addresses (Sheet 1 of 6)
Expanded
Address PC/AT Address Access Type (Byte/Word) Register Name Reset Value
DMA Controller and Bus Arb iter
F000H 0000H Byte DM A0TAR0/1 (Note 1) XX
F001H 0001H Byte DM A0 BYC0 /1 (Note 1) XX
F002H 0002H Byte DM A1TAR0/1 (Note 1) XX
F003H 0003H Byte DM A1 BYC0 /1 (Note 1) XX
F004H 0004H Reserved
F005H 0005H Reserved
F006H 0006H Reserved
F007H 0007H Reserved
F008H 0008H Byte DM ACMD1/DMASTS 00H
F009H 0009H Byte DMASRR 00H
F00AH 000AH Byte DMAMSK 04H
F00BH 000BH Byte DMAMOD1 00H
F00CH 000CH Byte DM ACL RBP Not a register
F00DH 000DH Byte DM ACL R Not a register
F00EH 000EH Byte DMACLRMSK Not a register
F00FH 000FH Byte DMAGRPMSK 03H
F010H Byte DMA0REQ0/1 XX
F011H Byte DMA0REQ2/3 XX
F012H Byte DMA1REQ0/1 XX
F013H Byte DMA1REQ2/3 XX
F014H Reserved
F015H Reserved
F016H Reserved
F017H Reserved
NOTES:
1. Byte pointer in flip-flop in DMA det ermines which register is accessed.
2. Shaded rows indicate reserved areas.