Mouse Events

1
Mouse Events

• An inquiry into the feasibility of utilizing
  mouse-clicks for single-stepping through a
  keyboard interrupt handler

2
Problem background

• We saw how the Pentiums trap-flag and
  debug-breakpoint registers can be used for
  single-stepping through parts of some interrupt
  service routines (for debugging)
• But a conflict arises when we attempt to debug
  the keyboard-input service routine (as in our
  projects do_read service), as our debugger
  also used keyboard input

3
Some other control device?

• To circumvent the contention for keyboard
  control, we ask can some other peripheral device
  substitute for the keyboard, as a convenient
  debugger user-interface?
• Our classroom machines do not offer us a way to
  access their serial ports (or parallel port),
  which would normally be appropriate
  device-interfaces for such a purpose, due to
  their being located in a separate place

4
Use the LAN?

• Another option might be to use the Local Area
  Network so the keyboard at another workstation
  could transmit commands to our debugger without
  making use of the local keyboard
• But this would involve a prohibitive amount of
  programming, due to the complexity of the
  networking software interface that has to be
  built in the absence of any OS

5
Maybe the mouse!

• It seems plausable that a mouse-click might
  serve to substitute for a keypress, as a way to
  control single-stepping
• But this might be tricky to manage, since the
  keyboard and mouse both interface to the same
  microcontroller chip
• Still, its worth exploring, if only to gain
  knowledge about mouse programming