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CompuGen 3250
I/O DIP switch and ISA bus address lines
Each of the switch positions 1 through 8 corresponds to an address line A2 through A9 from the ISA bus.
Switch Position
Address Line
1
A2
2
A3
3
A4
4
A5
5
A6
6
A7
7
A8
8
A9
As the CompuGen 3250 uses four I/O locations, there is no need to configure a switch for Address Lines A0 and
A1.
Calculating the switch settings
Some of the more generally available I/O addresses are listed on the following page with their equivalent SW2
switch settings. If you need to calculate alternate settings, use the following procedure.
1. Choose a hexadecimal address you want to calculate.
2. Convert the hexadecimal address into its binary form. (You can use the Windows scientific calculator for
this purpose.) Each digit in the binary form corresponds to an address line – the rightmost digit corresponds
with A0, the second rightmost corresponds with A1, etc., as shown in the table below.
Example:
the address 0300 converts to binary 1100000000.
Binary form
1 1 0 0 0 0 0 0
0 0
Address
Line
A9 A8 A7 A6 A5 A4 A3 A2
A1 A0
SW2 DIP Switch
8 7 6 5 4 3 2 1
- -
3. A “1” means “enable” and a “0” means “disable”. In the above example, switches 1 to 6 are DISABLED,
and switches 7 and 8 are ENABLED.
Remember that to enable an SW2 switch means positioning the switch AWAY from the switch number.
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