Did anyone notice Roman Black mentions that he is controlling current
with a LED PWM scheme?
The schematic is simple; the 8 segments (includes decimal point) connect direct to 8 PIC pins on PORTB, the 12 digit cathodes connect to 12 PIC pins on PORTA and PORTC. As you can see below the PIC just connects directly to the 20 pin connector on the LED display. It uses SOFTWARE to provide a low duty cycle and control the LED current for each segment.
He's controlling the average power
to the LED with direct PWM. Generally, average power is the limiting factor to driving common LEDs. Peak pulse current current may be very high as in the case of pulsed IR used in remote controls.