Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ukma!gatech!gitpyr!stat!curci
From: curci@stat.uucp (Ray Curci (scri))
Newsgroups: comp.sys.ibm.pc
Subject: Re: Interrupt Info Needed
Message-ID: <7418@pyr.gatech.EDU>
Date: 28 Feb 89 04:09:52 GMT
References: <111700044@uxa.cso.uiuc.edu>
Sender: news@pyr.gatech.EDU
Reply-To: curci@stat.fsu.edu (Ray Curci (scri))
Organization: Dept. of Statistics, Florida State Univ.
Lines: 31

In article <111700044@uxa.cso.uiuc.edu> sac90286@uxa.cso.uiuc.edu writes:
>	1) program the on-board timer chip to count down at a specified
>frequency, and once it has counted down to generate an interrupt,
>	2) write a handler to process this timer-generated interrupt which
>initiates the data read sequence,

The IBM AT has an Intel 8054 3 channel timer.  One channel is already used
for refreshing the DRAM which should be left alone.  Another channel is
used to maintain the software time under ms-dos (it is used to measure the
1/18.2 second ticks).  The remaining channel is used to generate a 
frequency to feed into the speaker to make sound.  IBM cleverly has an
AND gate where you can control one of the input in order to turn off the
sound and utilize the timer without making any noise.  If you are interested
I can mail you an excerpt from a Microsoft C program that programs this
chip.  It is probably possible to set up the chip to generate an interrupt
when it counts down, but I haven't tried it.  The definative source of info
on this timer is the data book from intel.  The latest data book I have that
describes it is "Intel Microprocessor and Peripheral Handbook Volume II -
Peripheral - 1987 #230843".  In the front cover is a price of $25 for the
two volume set and a toll free number for intel literature: 800-548-4725.

>	3) write another handler to process the "data ready" interrupt which
>is generated on the analog input board when the data is valid and ready to be
>read by the computer, which is on IRQ7.

I don't know which board you are using, but many data aquisition board 
contain timers for triggering purposes.  I have recently worked with the 
Metrabyte DASH-16, DAS-16, DAS-16F, DAS-8 which all have this capabililty.

>sac90286@uxa.cso.uiuc.edu
curci@stat.fsu.edu,  curci@nu.cs.fsu.edu