I have an old version of the C51 compiler which needs a parallel port dongle to generate a compiled output (Compiler V5.0/uVision 1.13). Parallel ports are disappearing on laptops and also on desktops. What options do I have? Is there a USB to parallel adaptor that may work? Do I have to upgrade to a modern version of compiler, which is not economically viable in this current economic climate?
For versions 6 and higher your answer is here: http://www.keil.com/support/docs/2866.htm
Version 5 is roughly 15+ years old. It is an old 16-bit DOS application and you will likely face a lot more problems than just getting the old dongle to work.
Since Version 8 PK51 is not protected with a hardware device.