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98640A Analog Input Interface
PREPARATION FOR USE
Calculating power requirements
Check your computer system manual to find how much power (in watts) is available from the com-
puter's power supply at each voltage the supply provides. Add the power requirements at each voltage
for all of the cards you already have in the computer.
Then add the power requirements of each
A -to-D card you will install to the totals.
If the power required at any voltage is greater than the power supply's rating at that voltage, you
must make some adjustment to your computer. Either reconfigure your system by omitting unneces-
sary cards or arrange to buy bus expanders through your Hewlett-Packard Sales and Service office.
Component Installation
There are no loose components to install on the A -to-D card or the wire termination assembly.
Boot-up 10 number
The
10
number of the card is a feature required by the operating system. The
10
register on the card
is hardwired to respond, "18", when polled during system boot-up. The operating system also checks
the address (which we will explain how to set below) of the A -to-O card. The
10
number and address
are used by the operating system to associate the card with an application program.
SWITCH SETTINGS
The A-to-D card has a DIP (dual in-line package) block of switches (SWl) located as shown in figure
2 -1. Switch numbers are on the switch block. These switches control the card's address and the
priority level of any interrupt the card transmits. You must select part of the address for the card.
The portion of the address you set on switches 1 to 5 is called the
select code.
The remainder of the
address
is
already hardwired. If you use a program which requires the card to send a specific level
hardware interrupt to the system, you must set the interrupt level the card will send before you install
the card in the computer. Figure 2-1 shows the switches set as they are when the A-to-O card leaves
the factory; the select code is 18 and interrupt level is 3.
The logical state of any switch corresponds to the numbers 0 and 1 silked -screened on the card just to
the right of the block of switches (SW
1).
To set a specific select code or interrupt level just set the
switches to the logical states shown in Table 2- 2. When a switch is closed, the bit it controls is low
(logical zero). When a switch is open, the bit it controls
is
high (logical one). You can
use
your finger-
nail or the tip of a ball-point pen to change a switch's setting.
2-2
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