ReAl

Sometimes avreal works unstable with LPT under OS Windows. Programming can be successfull or can fault, for example synchronisation lost.

A reason of these faults may be LPT polling by Windows Plug-and-Play (PnP) subsystem in order to detect connected devices. The polling is made at OS booting which is indicated by adapter LED blinking. Windows also can make the polling during its working. DLportIO.sys driver does not block access to LPT from another programs that why the polling can interfere in the microcontroller programming.

To avoid PnP interference download and run disable-lpt-poll.reg file. As you can see from the text, the file adds registry key which disables LPT polling.

REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Parport\Parameters]
"DisableWarmPoll"=dword:00000001