DIGITAL-LOGIC Microspace MSB900L User Manual page 39

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I/O Map
Continued...
I/O Addr. Function
3F1h Floppy Status R B
3F2h Floppy Digital Out
3F3h No Specific Usage
3F4h Floppy Cntrl Status
3F5h Floppy Data
3F6h No Specific Usage
3F7h Floppy Conf Reg
3F8h-3FFh UART/IR - COM1
480h No Specific Usage
481h DMA Channel 2 High Page
482h DMA Channel 3 High Page
483h DMA Channel 1 High Page
484h-486h No Specific Usage
487h DMA Channel 0 High Page
489h DMA Channel 6 High Page
48Ah DMA Channel 7 High Page
48Bh DMA Channel 5 High Page
48Ch-48Eh No Specific Usage
48Fh DMA Channel 4 High Page
490h-4CFh No Specific Usage
4D0h PIC Level/Edge
4D1h PIC Level/Edge
4D2h-4FFh No Specific Usage
Note 1: The Diverse Device Snoops writes to this port and maintains the MSB as NMI enabled. When low,
NMI is enabled. When high, NMI is disabled. This bit defaults high. Reads of this port return bits
[6:0] from the on-chip or off-chip target, while Bit 7 is returned from the "maintained" value.
MSB900/L Detailed Technical Manual V1.0
Size R/W Comment
8bit RO First Floppy.
8bit Shw@ First Floppy.
8bit ---
8bit RO First Floppy.
8bit Yes First Floppy.
8bit ---
8bit Shw$ First Floppy.
MSR bit enables/disables into I/O
3FFh space. (UART1 MSR
8bit --- 51400014h[18:16], UART2 MSR
51400014h[22:20]). Defaults to
LPC.
8bit WO Write LPC and DMA. Read only DMA.
Upper addr bits [31:24]. Write LPC and DMA.
8bit Rec
Read only DMA.
8bit WO Write LPC and DMA. Read only DMA.
Upper addr bits [31:24]. Write LPC and DMA.
8bit Rec
Read only DMA.
Upper addr bits [31:24]. Write LPC and DMA.
8bit Rec
Read only DMA.
8bit WO Write LPC and DMA. Read only DMA.
Upper addr bits [31:24]. Write LPC and DMA.
8bit Rec
Read only DMA.
--- ---
8bit Yes IRQ0-IRQ 7.
8bit Yes IRQ8-IRQ15.
--- ---
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