flaszowanie 3310 pod win 2000

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  • UserPort.rar
    • UserPort.pdf
    • UserPort.exe
    • UserPort.sys

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UserPort.rar > UserPort.pdf

UserPort Documentation
1 Summary
UserPort.SYS is a kernel mode driver for Windows NT/2000 that gives usermode programs access to I/O
Ports. This makes it possible to access hardware directly from a normal executable in the same way as under
Windows 95/98/ME. This driver does not work on Windows 95/98/ME and there is really no need to run it
anyway because I/O ports are always granted to usermode programs on these operating systems.
The driver can be used for the following purposes:
o To run software on Windows NT/2000 that normally only runs on Windows 95/98/ME.
o To easily access hardware like the parallel port and other I/O ports.
So what's the drawbacks with this wonderful software? Microsoft has for security reasons prohibited usermode
access to I/O ports. Opening up I/O ports creates a big security hole in your system. You should therefore
carefully set the grant lists to only give usermode access to the specific I/O ports you need. The default values
opens up a wide range of I/O ports and you should narrow it down.
If you are writing your own software you should only grant access through the file "\\.\UserPort". Access is then
given to your program when you open the file "\\.\UserPort". Other programs that don't open "\\.\UserPort" will
not have access to these I/O ports.

2 Installation
The driver can be installed in the following two ways:
Start UserPort.EXE and add the addresses you want and remove
the others and clock on start.
o Run UserPort.EXE with the driver filename and path as an argument
i.e. run UserPort.EXE X:\YOURDIR\UserPort.SYS
Add the addresses you want and remove the others and clock on start.
You should now have usermode access to the addresses you have chosen.

3 Examples
Port instructions are not included in development environments (such as Visual C++ and Delphi) because direct
I/O access isn't allowed by the operating system. You will therefore need to include a portion of assembler code
into your software in order to access your hardware, see Figure 2, 3 and 4.
BYTE inportb(UINT portid)
unsigned char value;
__asm mov edx,portid
__asm in al,dx
__asm mov value,al
return value;

void outportb(UINT portid,
BYTE value)
__asm mov edx,portid
__asm mov al,value
__asm out dx,al


Figure 2: Read I/O port
if (inportb(0x379) & 0x10) {
outportb(0x37a,inportb(0x37a) | 0x01);
outportb(0x37a,inportb(0x37a) & 0xfe);

Figure 3: Write I/O port

Check "Select" pin
Write character 'A' to printer
Set "strobe"
Wait 1ms
Clear "Strobe" pin

Figure 4: Print 'A' example using direct I/O access
Figure 4 shows how simple it now is to access hardware from a usermode program. The UserPort package
should contain the files IOPort.c, IOPort.h and IOPort.pas to be when developing C, C++ and Delphi programs.

4 Technical Description
The driver gives user mode program access to selected ports by changing the x86-processors IOPM (I/O
Permission Map). Figure 1 shows how the driver works. For a detailed description on the TSS see Intel
proccessor handbooks.
Task State Segment








IOPM offset
IOPM for processes
that opens


IOPM for all processes

Figure 1: 80x86 TSS description
The original size of the TSS is 0x20ab and the driver extends it to 0x2135. The default IOPM offset is 0x20ad
and this value is rewritten by the OS on every task switch. The IOPM offset must therefore be changed with the
undocumented function Ke386IoSetAccessProcess, which sets the IOPM offset to 0x88. The
AllProcessesIOPM is written to 0x20ad because this is the default IOPM offset for all processes and the
ThroughCreateFileIOPM is written to 0x88 because the Ke386IoSetAccessProcess function sets the
IOPM offset to 0x88. The Ke386IoSetAccessProcess function is called when a user mode program opens
the file "\\.\UserPort". The driver loads the two IOPM:s from:
It will use default values below if these doesn't exist.
This driver is influenced and inspired by an article written by Dale Roberts 8/30/95, published in May 96 Dr
Dobbs Journal, see