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DIGITAL-LOGIC AG MSB900/L Detailed Technical Manual V1.0
36
5.9.2. System I/O map
The following table details the legacy I/O range for 000h through 4FFh. Each I/O location has a read/write
(R/W) capability.
Note the following abbreviations:
--- Unknown or can not be determined.
Yes Read and write the register at the indicated location. No shadow required.
WO Write only. Value written can not be read back. Reads do not contain any useful information.
RO Read only. Writes have no effect.
Shw
The value written to the register can not be read back via the same I/O location. Read back is
accomplished via a “Shadow” register located in MSR space.
Shw@ Reads of the location return a constant or meaningless value.
Shw$ Reads of the location return a status or some other meaningful information
Rec
Writes to the location are “recorded” and written to the LPC. Reads to the location return the re-
corded value. The LPC is not read.
I/O Map
I/O Addr.
Function Size
R/W Comment
000h Slave DMA Address - Channel 0 8bit Yes 16bit values in two transfers.
001h Slave DMA Counter - Channel 0 8bit Yes 16bit values in two transfers.
002h
Slave DMA Address - Channel 1 8bit Yes 16bit values in two transfers.
003h
Slave DMA Counter - Channel 1 8bit Yes 16bit values in two transfers.
004h
Slave DMA Address - Channel 2 8bit Yes 16bit values in two transfers.
005h
Slave DMA Counter - Channel 2 8bit Yes 16bit values in two transfers.
006h
Slave DMA Address - Channel 3 8bit Yes 16bit values in two transfers.
007h
Slave DMA Counter - Channel 3 8bit Yes 16bit values in two transfers.
008h
Slave DMA Command/Status - Channels [3:0] 8bit Shw$
009h
Slave DMA Request - Channels [3:0] 8bit WO Reads return value B2h.
00Ah
Slave DMA Mask - Channels [3:0] 8bit Shw@
Reads return value B2h.
00Bh
Slave DMA Mode - Channels [3:0] 8bit Shw@
Reads return value B2h.
00Ch
Slave DMA Clear Pointer - Channels [3:0] 8bit WO Reads return value B2h.
00Dh
Slave DMA Reset - Channels [3:0] 8bit WO Reads return value B2h.
00Eh
Slave DMA Reset Mask - Channels [3:0] 8bit Shw@
Reads return value B2h.
00Fh Slave DMA General Mask - Channels [3:0] 8bit Shw@
Reads return value B2h.
010h-01Fh No Specific Usage --- ---
020h
PIC Master - Command/Status 8bit Shw$
021h
PIC Master - Command/Status 8bit Shw$
022h-03Fh No Specific Usage --- ---
040h
PIT – System Timer 8bit Shw$
041h
PIT – Refresh Timer 8bit Shw$
042h
PIT – Speaker Timer 8bit Shw$
043h
PIT – Control 8bit Shw$
044h-05Fh No Specific Usage --- ---
Continued…