Subject: Re: Game port From: Rubywand Date: Sun, Dec 20, 1998 21Ç40@ Message-id: <367DD123.327F76D7@swbell.net> David Empson writes ... > .... > > A final note: the IIc does not have a button 2 input, and its button 0 > and 1 inputs are not quite the same as other machines, since they double > up as mouse detection and button signals (which use the opposite logic - > connecting to ground when the mouse is plugged in or the button is > pressed). The last statement is a bit hard to follow. If the normal (when plugged in) mouse button status is at Gnd, how can pressing a button bring the line to Gnd? Do you mean that plugging in the mouse puts Mouse ID (PB1) at Gnd and that Mouse Button (PB0) is normally at "1" until it is pressed? Regarding pinout of 9-pin A2 mouses, is the following correct? >> The IIe/IIc/Mac Plus mouses can plug into the //c or IIc+ Game/Mouse port or, on a IIe, into the 9-pin socket of a Mouse Card. When plugged into the //c or IIc+, several pins are redefined for use with a mouse. DB-9 Female Socket (on computer) ,---------------------. \ 5 4 3 2 1 / \ 9 8 7 6 / `-----------------' Mouse Usual Game Port Function 1 MOUSE ID Pushbutton 1 2 +5V +5V 3 GND GND 4 XDIR Game Control 2 or PDL2 (Joystick-2 X-axis) 5 XMOVE Game Control 0 or PDL0 (Joystick-1 X-axis) 6 n.c. Pushbutton 2 (not on //c) 7 MOUSE BUTTON Pushbutton 0 8 YDIR Game Control 1 or PDL1 (Joystick-1 Y-axis) 9 YMOVE Game Control 3 or PDL3 (Joystick-2 Y-axis) << Does the IIc+ also omit a connection for PB2? > > You cannot reliably put a TTL level into a IIc. The only officially > supported input combinations are a switched +5V with pulldown (as on > earlier machines), or a similar transistor configuration (fully > saturated PNP, with Vce <= 0.3V, and current into the IIc >= 30 mA, > according to the techincal reference). > > The IIc manual specifically excludes a schottky gate output, switched > ground through a transistor (open collector), and emitter follower > transistor configuration. It seems like about the only way to exclude Open Collector is for the //c PB inputs to include a resistor going to Ground. Something like 1200 Ohms would let you use standard A2 joysticks without sucking too much more current during a button push. To interface such an input to TTL, you would be stuck with something like ... +5V \ E \ | about 1k |--B-----/\/\/\--------<--- Output from TTL gate PB input / | ---------o----/ C PNP Transistor | Z Z | Gnd i.e. your saturated PNP transistor. Would the above circuit work on a //c? Rubywand