PC interface for Nintendo joystick

Awkward keyboard commands and uncomfortable mouse control can spoil even the most attractive PC game. The ideal solution would be simple operation, as offered by the Nintendo 64, combined with the processing power of a PC. This article describes how to connect a Nintendo 64 controller to the PC game port.This circuit allows a Nintendo 64 controller to be connected to the PC game port (or a sound card), without requiring any additional drivers to be installed. The Nintendo 64 controller is a widely-used unit that combines high quality with a low price. With this approach, you can run PC games with the comfortable Nintendo 64 controller instead of using the PC keyboard and mouse.

Resistors:
R1-R4 = 470Ω
R5-R8 = 220Ω
R9 = 10kΩ
R10 = 2kΩ2
R11 = SIL-resistor array 4x10kΩ
Capacitors:
C1 = 10µF 16V radial
C2 = 100nF
C3,C4 = 27pF (*)
C5 = 100µF 16V radial
Semiconductors:
D1 = LED, low current
IC1 = AT89C2051-24PC (order code 006504-1)
Miscellaneous:
K1 = 15-way sub-D plug fr board edge mounting
X1 or XO1 = quartz crystal, 24MHz, fundametal resonance or 24MHzoscillator module (Seiko-Epson SG531P-24MHz)