PMAC-Lite Hardware Reference
Bus Address Jumper Setup
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BUS ADDRESS JUMPER SETUP
Jumpers E91, E92, E66, E67, E68, E69, E70, and E71 on the PMAC-Lite determine the base address of
the card in the I/O space of the host PC’s expansion bus. Together, they form a binary number that
specifies the 16 consecutive addresses on the bus where the card can be found.
The jumpers form the base address in the following fashion:
Jumper
E91 E92 E66 E67 E68 E69 E70 E71
Bit #
11
10 9 8 7 6 5 4
Dec Value
2048
1024 512 256 128 64 32 16
Hex Value
800 400 200 100 80 40 20 10
If a jumper is ON, the value it contributes to the base address is ZERO.
If a jumper is OFF, the value it contributes to the base address is given in the table above.
On the PMAC-Lite, the jumpers are physically arranged in the same order they are presented in the above
table.
From Jumper Configuration To Address
To determine the address specified by a given jumper configuration, use the following formula:
(Decimal)
Address = 2048*E91 + 1024*E92 + 512*E66 + 256*E67 + 128*E68 + 64*E69 + 32*E70 + 16*E71
(Hexadecimal)
Address = $800*E91 + $400*E92 + $200*E66 + $100*E67 + $80*E68 + $40*E69 + $20*E70 +
$10*E71
In each case, Exx = 1 if the jumper is OFF; Exx = 0 if the jumper is ON.
Example: On a PMAC card, the jumpers are in the following configuration:
E91 E92 E66 E67 E68 E69 E70 E71
ON ON OFF OFF ON ON ON ON
The address can be computed as:
Decimal Address = 0 + 0 + 512 + 256 + 0 + 0 + 0 + 0 = 768
Hex Address = 0 + 0 + $200 + $100 + 0 + 0 + 0 + 0 = $300
From Address to Jumper Configuration
Once an I/O address on the PC expansion port has been selected, the following procedure can be used for
setting the address jumpers.
1. Convert the address to a 3-digital hexadecimal value ($000 to $FFF, representing 0 to 4095). If the
value does not fit in this range, you will not be able to set PMAC for this address. Make sure the last
digit is 0; only addresses divisible by 16 are permitted as PMAC base addresses.
2. Take the first hex digit and convert it to binary. The binary digits represent bits 11 through 8 of the
base address. Assign each binary digit to jumpers as follows:
Bit #
11(MSB) 10
9 8(LSB)
Jumper
E91 E92 E66 E67
Digit Value
8 4 2 1
Setting for 1
OFF OFF OFF OFF
Setting for 0
ON ON ON ON
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