G
Guest
Hi,
I am a firmware deleveloper who uses the PC's parallel port extensively for
communication with embedded systems I design (usually 8-bit
microcontrollers). I attempt to directly access the parallel port hardware
using input() and output() functions. Under XP, none of these programs has
any effect on the parallel port signals. I understand there are
hardware/software protection means that turn control over to XP when DOS
programs attempt to directly access hardware, so I have hunted the net for
kernel mode drivers to enable port access, such as UserPort. With UserPort
installed, I/O does make it to the parallel port, however, attempts to write
and retrieve data from the main parallel port I/O data register (base+0)
results in I/O errors (the data read doesn't *always* match what was written).
Any thoughts?
Thanks for your help,
Scott
I am a firmware deleveloper who uses the PC's parallel port extensively for
communication with embedded systems I design (usually 8-bit
microcontrollers). I attempt to directly access the parallel port hardware
using input() and output() functions. Under XP, none of these programs has
any effect on the parallel port signals. I understand there are
hardware/software protection means that turn control over to XP when DOS
programs attempt to directly access hardware, so I have hunted the net for
kernel mode drivers to enable port access, such as UserPort. With UserPort
installed, I/O does make it to the parallel port, however, attempts to write
and retrieve data from the main parallel port I/O data register (base+0)
results in I/O errors (the data read doesn't *always* match what was written).
Any thoughts?
Thanks for your help,
Scott