BBC Mouse Drivers - MDFS::Info.Comp.BBC.Mouse

MDFS::Info.Comp.BBC.Mouse

BBC Mice and Mouse Drivers

A quadrature mouse (such as an Archimedes mouse) can be plugged into the BBC user port. It should be wired up as shown below. You can simply put a 20pin IDE head on the end of the mouse cable, but it is useful to put a 9-pin D socket (female, no pins) on mice using the Master Compact pinouts.

  +5v  1 |  2  CB1 - Xaxis                   /
       3 |  4  CB2 - Yaxis                 / 1| Xdir
   0v  5 |  6  D0  - Xdir            Left |6  |
       7 |  8  D1                         |  2| Right
       9 | 10  D2  - YDir             +5v |7  |
      11 | 12  D3                         |  3| Middle
      13 | 14  D4                      0v |8  |
      15 | 16  D5  - Left                 |  4| Ydir
      17 | 18  D6  - Middle         Yaxis |9  |
      19 | 20  D7  - Right                 \ 5| Xaxis
     USER PORT                               \
                                    COMPACT MOUSE PORT

A short adapter with a 20-pin IDC header and a 9-pin D plug (male, pins) makes the user port accessible for plugging in the mouse and lets mice be interchangeable between Compacts and non-Compacts.

Mouse Driver

Mouse.zip contains a *MOUSE command which provides a mouse driver. DFS224+Mse and DFS229+Mse are DFS ROM images for the Master and Master Compact that include a mouse driver in the spare ROM space using ROMMouse.src.

Once the mouse driver has been turned on with *MOUSE ON, then the mouse position and button state can be read using OSBYTE or OSWORD. The OSBYTE routines are accessible using the INKEY and ADVAL calls.

`ADVAL(7)`	Osbyte &80,&07,&00	Mouse X position
`ADVAL(8)`	Osbyte &80,&08,&00	Mouse Y position
`ADVAL(9)`	Osbyte &80,&09,&00	Mouse buttons %rml, set if pressed
`INKEY-10`	Osbyte &81,&F6,&FF	Mouse left button
`INKEY-11`	Osbyte &82,&F5,&FF	Mouse middle button
`INKEY-12`	Osbyte &82,&F4,&FF	Mouse right button

The mouse driver also responds to the AMX OSWORD 64 call. On exit:

`XY+0, XY+1`	Mouse X position
`XY+2, XY+3`	Mouse Y position
`XY+4`	Text X position
`XY+5`	Text Y position
`XY+6`	Mouse buttons b7=R, b6=M, b5=L, clear if button pressed

MouseTest is a short BASIC program that tests the mouse calls and displays their return values.

Mouse programming

MouseLib is a BASIC library providing a handful of mouse interface routines:

`DEFPROCMouse_Init`	initialises mouse variables mx%,my%,bl%,bm% and br%.
`DEFPROCMouse_UntilAction`	waits until the mouse changes state, by being moved or a button being pressed, or until a keyboard key is pressed.
`DEFPROCMouse_Read`	reads the mouse state into mx%,my%,bl%,bm% and br%, being the mouse x and y position, and the button left, middle and right state.
`DEFPROCPointer_Init`	initialises a simple pointer.
`DEFPROCPointer_Draw`	draws a pointer at the current graphics position.
`DEFPROCPointer_UntilAction`	waits until the mouse buttons change state or a keyboard key is pressed, drawing a pointer at the mouse position while waiting.

using the Mouse library a main program just needs to start by calling PROCMouse_Init and use PROCPointer_UntilAction in the main loop.

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Last update: 09-Jan-2006