Loading determines what Timer will use as the loading on the output pin. The output-capacitance value is based on the I/O standard selected in the I/O Standard cell. This option is not available in ACTgen.
The default loadings for different I/O standards are as follows:
35 pf for TTL, LVTTL, and CMOS
50 pf for 5V PCI
10 pf for 3.3V PCI
Note that these values are for Timer use only; designers can customize the I/O loading for timing analysis. They do not affect the I/O configuration.