Selecting a base address, Assigning an interrupt level, Page 3 sensoray model 425 instruction manual – Sensoray 425 User Manual
Page 5
Page 3
Sensoray Model 425 Instruction Manual
Selecting a Base Address
First Address Nibble (MSB)
Adrs
A15
A14
A13
A12
0
On
On
On
On
1
On
On
On
Off
2
On
On
Off
On
3
On
On
Off
Off
4
On
Off
On
On
5
On
Off
On
Off
6
On
Off
Off
On
7
On
Off
Off
Off
8
Off
On
On
On
9
Off
On
On
Off
A
Off
On
Off
On
B
Off
On
Off
Off
C
Off
Off
On
On
D
Off
Off
On
Off
E
Off
Off
Off
On
F
Off
Off
Off
Off
The 425 board occupies a block of 64 consecutive addresses
in the ISAbus 16-bit I/O space. This block must begin on a
64-byte address boundary. The first address in the block —
the “base address” — is assigned by option shunts A6-A15.
Care must be exercised to ensure that no other
devices use addresses in the block assigned to the
425. Use the tables shown below to determine
the proper settings for your application.
For example, to program the board
base address to 0300 hex, install
shunts A15-A10 and A7-A6, and
remove shunts A9-A8.
Note: default settings (address 0C80) in bold
Second Address Nibble
Adrs
A11
A10
A9
A8
0
On
On
On
On
1
On
On
On
Off
2
On
On
Off
On
3
On
On
Off
Off
4
On
Off
On
On
5
On
Off
On
Off
6
On
Off
Off
On
7
On
Off
Off
Off
8
Off
On
On
On
9
Off
On
On
Off
A
Off
On
Off
On
B
Off
On
Off
Off
C
Off
Off
On
On
D
Off
Off
On
Off
E
Off
Off
Off
On
F
Off
Off
Off
Off
Third Address Nibble
Adrs
A7
A6
0
On
On
4
On
Off
8
Off
On
C
Off
Off
Several onboard subsystems are capable of
generating interrupt service requests to the host
processor. All three encoder counters as well as relay
channels 0-15 may source such requests.
To compensate for the limited interrupt resources in
ISAbus systems, the 425 board is restricted to a
single physical interrupt request signal for all
onboard interrupt sources.
For maximum flexibility, the board’s interrupt
request may be assigned to any available IRQ line on
the ISAbus. When choosing an interrupt level for the
425 board, verify that no other boards are using the
same level.
If the 425 board will not be sourcing interrupt requests,
be sure that no option shunts are installed in any of the
IRQ positions.
If you will be using the 425
board to generate interrupts,
you must install an option shunt
to assign an interrupt level to
the board. Install a shunt at the
position corresponding to the
desired interrupt service level
per the table to the right. Make
sure that only one interrupt
level is selected.
IRQ
Position
3
IRQ3
4
IRQ4
5
IRQ5
6
IRQ6
7
IRQ7
9
IRQ9
10
IRQ10
11
IRQ11
12
IRQ12
14
IRQ14
15
IRQ15
Assigning an Interrupt Level