heintze@fmcsse.enet.dec.com (Siegfried Heintze) (09/04/90)
I'm wondering what options there are for solving programming
problems with MSDOS. I have posted the following query in other
MSDOS.PROGRAMMING news groups and I am still hoping for some
responses from VNEWS readers.
I would like to query for suggestions on other means of
investigating my problem of MSDOS hanging when I call INT 0x33
FUNC 2.
I can think of
(1) Books on the subject. I have looked thru several - none
address this specific issue. There is one expensive
book called (something like) "MSDOS System programming"
that gives an example in text mode but not graphics.
(2) Calling MS customer support. Is there such an animal for
detailed programming questions? What is the phone number
and how much does it cost?
(3) Buying one of those expensive disassemblers to disassemble
my mouse driver and possibly part of MSDOS to better
understand exactly what is happening when I use an INT 33
FUNC 2.
(4) Buying one of those very expensive debuggers like
periscope for ~$400. I don't know enough about them to
know exactly how they could help me - but for that price
they ought to be able to work miracles.
Which option would you recommend? Can you think of other
options?
Thanks,
Sieg
=======================================================================
Here is the original query I have posted in
COMP.OS.MSDOS.PROGRAMMING:
I'm using MSDOS software interrupt 0x33, function 0x0c to
establish a routine (called ime) to be called by the mouse driver
everytime the mouse changes state (ie, everytime a button is
depressed or released or the position of the mouse changes.)
This works because I can call the zortech routine "sound_click()"
to verify that it is working.
I remember reading somewhere that it is necessary to call
interrupt 0x33 function 2 before writing to the VGA to prevent a
conflict. This function hides the mouse pointer on the VGA to
prevent the mouse driver and you from trying to access VGA
simultaneously. This is an important consideration because
writing to the VGA is not an atomic operation. It consists of
writing to multiple VGA registers via I/O ports. Interrupting
this sequence with another write sequence would not be desireable.
So we tell the mouse driver not update the mouse pointer on the
VGA while we are accessing the VGA display RAM and when we are
done we use INT 0x33 func 1 to display the mouse pointer again.
I tried just writing to the VGA display from the routine called by
INT 0x33 func 0x0c and it did not hang. But when I tried to
write a character to the VGA display using a call to MSDOS (INT
0x10 func 9) it hangs. No surprise, I probably needed to hide
the mouse.
So I call int 0x33 func 2 to hide the mouse inside ime. This
hangs my machine. Why? How do I diagnose this problem further?
Sieg