Changes

PositionThe interface described here was loaned to arnoldemu by yoshi.doshi. PCB has a 50-way edge connector. There is no through connector. The mouse connects via a 9-pin female D-sub (standard joystick socket) which is on the PCB. The board is labelled "(C) KEMPSTON MICRO AMSTRAD MOUSE I/F" and "ISS B". The ICs are labelled and are:  IC1 DM74LS00N QUAD 2-INPUT NAND IC2 DM74LS191N SYNCHRONOUS UP/DOWN COUNTERS WITH DOWN/UP MODE CONTROL (4-bit binary counter) IC3 DM74LS191N SYNCHRONOUS UP/DOWN COUNTERS WITH DOWN/UP MODE CONTROL (4-bit binary counter) IC4 74LS125APC QUAD 3-STATE BUFFER IC5 DM74LS191N SYNCHRONOUS UP/DOWN COUNTERS WITH DOWN/UP MODE CONTROL (4-bit binary counter) IC6 DM74LS191N SYNCHRONOUS UP/DOWN COUNTERS WITH DOWN/UP MODE CONTROL (4-bit binary counter) IC7 DM74LS138N 1-OF-8 DECODER/DEMULTIPLEXER IC8 DM74LS257BN 3-STATE QUAD 2-DATA SELECTORS/MULTIPLEXERS IC9 DM74LS257BN 3-STATE QUAD 2-DATA SELECTORS/MULTIPLEXERS The mouse that comes with the interface has 2 buttons. It is a ball mouse. Unknown brand.Green label reads "Q.C. PASSED. MADE IN TAIWAN. R. O. C.". Mouse has 9-pin DIN like a joystick. Unknown if compatible with Atari ST or Amiga or neither. The schematics and PCB are 90% the same as the Spectrum's. They differ in the port decoding. NOTE: * Counters are reset to 0 at power on. * Counters are NOT reset to 0 when using bus reset (reset switch) === I/O decoding === Decoding seems to be (some testing to confirm this):  I/O port for X position is decoded as xxxx x0x1 xxx0 xxx0 (FBEE is normally used) I/O port for Y position is decoded as xxxx x0x1 xxx0 xxx1 (FBEF is normally used) I/O port for Buttons is decoded as xxxx x0x0 xxx0 xxxx (FAEF is normally used) Confirmed connected:A10, A0, A4, A8. ==== Movement ====  Port FBEEh READ: Kempston Mouse 8 bit X position(left: -ve, right: +ve) Port FBEFh READ: Kempston Mouse 8 bit Y position(up: +ve, down: -ve) NoteNOTE: * Movement is accumulated so you only need to read the mouse status when you want e.g. once per frame.* Speed is 1 for slow movement of the mouse and 12 for very fast movement.* The position values aren't are not reset after reading. * The position values do not change if the mouse is not moving * Position values wrap around e.g. when moving left with movement speed of 1, 0 wraps around to ff (0-1 -> ff) and when moving right with movement speed of 1, ff wraps around to 0 (ff+1->0)* To calculated the distance moved since last read:subtract the new value read from the previous value read and AND with ff. The value is the amount of movement.0 means no movement. -ve means moving left/down, +ve means right/up. 

==== Buttons:==== 

bit 0: Left Right Button (active low) bit 1: Right Left Button (active low) bit 2..7: unknownnot used. report as high (1)

// # initMouse initializes variables and centers the mouse pointer on screen function def initMouse() {: maxX = 639; maxY = 399; // # centering the mouse pointer on the screen virtualX = maxX >> 1; // virtualX = # maxX/2 virtualY = maxY >> 1; // virtualY = # maxY/2 // # store raw mouse values oldX = inp(&FBEE); oldY = inp(&FBEF); // # get mouse pointer position refreshMouse();  }def refreshMouse(): # get raw mouse values rawX = inp(&FBEE) rawY = inp(&FBEF) # get the relative mouse displacement since last call deltaX = rawX - oldX deltaY = rawY - oldY # store raw mouse values oldX = rawX oldY = rawY # calculate new unclipped virtual position virtualX = virtualX + deltaX virtualY = virtualY - deltaY # Kempston mouse Y-axis is inverted compared to screen coordinates! # perform clipping if virtualX < 0: virtualX = 0 elif virtualX > maxX: virtualX = maxX if virtualY < 0: virtualY = 0 elif virtualY > maxY: virtualY = maxY # now we translate position from the virtual screen to the current CPC screen mode mouseX = virtualX if graphicsMode == 2 else (virtualX >> 1 if graphicsMode == 1 else virtualX >> 2) mouseY = virtualY >> 1 == Manual == * Any manual exists?  == Downloads == * Any kempston example or driver software exists?

[[Category:Peripherals]][[Category:Input Device]]