Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!bpa!cbmvax!vu-vlsi!lehi3b15!lafcol!pilgrimk
From: pilgrimk@lafcol.UUCP (Guru Jee)
Newsgroups: comp.lang.pascal
Subject: Int 1CH
Keywords: quest qe ce?
Message-ID: <369@lafcol.UUCP>
Date: 31 Jan 89 05:03:46 GMT
Organization: Academic Computer Center, Lafayette College
Lines: 51

I'm using INT 1CH to install a clock on my screen. Problem is that
it works when it wants to. 

The problematic part of the code (at least I think that this might be
it) is:

 ....
 GetIntVec($1C, Int1C);
 SetIntVec($1C, @ClockProcedure); {call ClockProcedure ~ 18 time/sec}
 ....

then there is an exit procedure (yes, I did force a far call using $F+) 
which contains, among other things

 ....
 SetIntVec($1C, Int1C);
 ....

which is supposed to reset the INT 1C to its original address.

When the program works, it works FINE. I can simultaneously display
a clock and have the user type in stuff. 

When it doesn't, it may do any of the following:

 i. Never return to the C> prompt but the computer can be rebooted
    using the Ctrl-Alt-Del sequence
 
 ii. Never return the C> prompt and lock the keyboard up so
     to reset, the ON/OFF switch must be used.

While running the program from within the integrated environment, 
both of the afore-mentioned errors show up as stack overflow errors. 
(at which point the computer crashes.) I have tried setting the
stack size to its limit (65520) but no way jose - same problem.

One last word. Without the INT 1C part, everthing works as I expect
it to - ALL THE TIME. Introduce the INT 1C and I have a temperamental
program.

Do I have to use STI and CLI instructions?
If so, should these be installed in the interrupt procedure?
Should I be using INT 1C in the first place?

One more thing. The code to display the time onscreen is contained in
a unit. The procedure which is global looks like
         DisplayDate(X,Y: byte); {X,Y are screen coords}

Any helpful hints would be appreciated. If this made no sense to 
you, or if you'd like to see the source code, I be happy to mail
it to you.