As you probably already know, Amstrad CPC Joyport,doesn't provide any 5volt power supply, which prevents the functioning of Auto fire switches and also various adapters desgined for 9pin Joyport.
Unfortunately, adding the 5v to joyport is not as simple as connecting the 5volt supply to the coresponding pin of
joystick port connector, because of the strange way amstrad gameport
functions. Amstrad doesn't have specific port for joystick but instead, joyport is multiplexed with keyboard (and that's why you get charcters on screen when you move joystick or press a fire button). In order to do that, the common-com signal (which normally would be the "ground"/0V),is pulsed, where every 0.02 seconds
goes from high to low, and only then, amstrad scans joystick status.
So, what i have to
show you here, is a rather simple circuit
that will provide the necessary 5volt supply (without interefere with the scaning of joyport, which can cause problems), to
joytisck's DB9 connector, thus enabling ,not only the usage of autofire, but also, any adapter designed for DB9 gameport, like Amiga/Atari ST Mouse Adapter ,a DB15 PC Joystick Adapter,a Wireless Bluetooth Joystick Adapter and various Usb Joystick/Gamepad Adapters!
So, here is the circuit:
Anyone interested, please contact at: ikonsgr745@hotmail.com
In essence, a 74LS367 3-state Hex Buffer is inserted between joystick and amstrad's joyport.
Anyone interested, please contact at: ikonsgr745@hotmail.com