The is the final and most stable release of Microchip's legacy C compiler for 18-bit PIC microcontrollers before it was officially superseded by the MPLAB XC8 compiler . Key Characteristics of v3.47
Older full versions used a parallel port dongle (Sentinel). The "best" experience is with the software license version (v3.47 and higher) which does not require a dongle. mplab c18 347 full version best