~ National ~ Semiconductor - Al Kossow's Bitsavers

I/O SPACE
The I/O space and EthernetlCheapernet configurations are
selected using the various I/O jumpers. There are 4 sets of
jumpers that should be programmed prior to installation of
the evaluation board into the PC environment. There are:
J4
I/O address, interrupt selection, DMA channel
assignment
J 1 C-J7C, J7E Select Ethernet or Cheapernet
Figure 5 depicts the location of the jumpers on the evaluation
board.
The Factory Installed Configuration Is:
J4
I/O base = 300h
Interrupt =
IRQ3
DMA = DREQ1, DACK1
J1 C-J7C, J7E Cheapernet selected
The evaluation board uses 32 I/O locations in the PC's I/O
space. The base address is fixed at 300h and is not selectable
using jumpers. (See Switch settings section.) The I/O
map is shown below:
BASE + OOh
01h
02h
03h
04h
05h
06h
07h
•
Ofh
10h
•
1fh
COMMAND REGISTER
NIC REGISTER
SPACE
•
•
•
•
•
•
•
I/O PORTS
•
•
NOTES: The Nle's Command Register is always mapped at Base + O. The
N Ie registers are Base + 01 to Base + Of; Of will contain different
registers depending on the value of bits PSO and PS1 in the Command
Register. These two bits select one of three register pages.
For additional information consult the DP8390 data sheet.
The NIC uses the remote DMA channel to read/write data from/to
the 8k x 8 Buffer RAM on the evaluation board. Typically a DMA
channel on the PC is used in conjunction with the Nle's remote
DMA. The I/O ports are then serviced by the DMA channel. If a
DMA channel on the PC is not available, the Nle's DMA can still be
used by accessing the 110 ports using programmed 1/0. Reading
the I/O port address will result in a RACK strobe to the NIC while
writing the I/O port address will result in a WACK strobe to the NIC.
SWITCH SETTINGS
Jumper J4 allows assignment of 110 Address Bases, DMA
channel assignments and Interrupt Request assignments.
The jumper configuration is shown below and described in
the following sections.
I: • • • • • •
I I I I 0 0 I
R R R R R R R
QQQQEEQ
2 3 4 5 Q Q 5
1 3
I/O BASE ADDRESS
• •
• •
o 0
A A
C C
K K
1 3
• : I
B B
A A
S S
E E
2 3
TLlF/9179-6
The 110 Base Address for DP8390B boards is fixed at 300h
and is not selectable.
INTERRUPTS
The NIC will generate interrupts based on received and
transmitted packets, completion of DMA and other internal
events. The interrupt can be connected to Interrupts 2, 3, 4
or 5 (IRQ 2,3,4,5) via Jumper J4. Interrupt 5 is also provided
as a software driven DMA Channel. If Interrupt 5 is being
used as a DMA channel Interrupt 5 cannot be chosen for
the NIC interrupt. The figures below illustrate the jumper
positions for the various interrupt levels.
~:
I:
• •
• •
•
• •
• •
•
•
•
•
•
•
•
• • •
• • •
•
•
Interrupt 2
: I
TL/F/9179-9
Interrupt 3
(Factory Installed)
•
•
•
•
: I
TL/F/9179-10
Interrupt 4
: I
TLIF/9179-11
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