Hi, I am trying to wrestle control of COM1 from windows 98, and need some help.
So far I have written a simple vb gui (just a simple form) that loads a dynamic vxd that I wrote as well. The vb and the vxd loads and responds correctly.
My problem is with gaining control of the serial port. I have tried virtualizing the port, stealing the port and other things, yet nothing lets the port become active so to speak. If I invoke the debugger, I can read from the serial ports registers (COM1, 03F8-03FF) and all registers read "FF". As though its not there and the data bus is just floating.
So I wrote another vb gui that uses the vb comm control. It runs and listens to whatever is coming in on the serial port and pastes it onto a text box, and works correctly. So obviously the serial port works, and when I invoke the debugger while it's running, I can read the serial port's registers correctly. No more FF's.
Does anyone have a clue what is going on? Can windows be intercepting the debuggers attempts to read the ports? I thought the debugger had 100% access to the machine (it runs in ring 0), how could it not see the serial port at all times?
Thanks.
So far I have written a simple vb gui (just a simple form) that loads a dynamic vxd that I wrote as well. The vb and the vxd loads and responds correctly.
My problem is with gaining control of the serial port. I have tried virtualizing the port, stealing the port and other things, yet nothing lets the port become active so to speak. If I invoke the debugger, I can read from the serial ports registers (COM1, 03F8-03FF) and all registers read "FF". As though its not there and the data bus is just floating.
So I wrote another vb gui that uses the vb comm control. It runs and listens to whatever is coming in on the serial port and pastes it onto a text box, and works correctly. So obviously the serial port works, and when I invoke the debugger while it's running, I can read the serial port's registers correctly. No more FF's.
Does anyone have a clue what is going on? Can windows be intercepting the debuggers attempts to read the ports? I thought the debugger had 100% access to the machine (it runs in ring 0), how could it not see the serial port at all times?
Thanks.
To answer my own question. Yes windows does indeed trap I/O access.
I just started reading Karen Hazzah's book on writing vxd's. Paqe 13, spelled it out.
So off to read page 14 LOL.
I just started reading Karen Hazzah's book on writing vxd's. Paqe 13, spelled it out.
So off to read page 14 LOL.